Autocad Tutorials

Making a Layer the Current Layer on Autocad 2011

2012-01-12T19:44:00.000-08:00

Making a Layer the Current Layer on Autocad 2011

Once you have created some layers you will want to start using them. As indicated above, you can only draw on one layer at a time. In order to draw on a particular layer you must first make it the current layer. As usual with AutoCAD there are a number of alternatives. You could, for example, use the Layer command, Layer... from the Format pull-down or from the Object Properties toolbar. As you have seen previously, this command brings up the Layer & Linetype Properties dialogue box. To set the current layer, select a layer name from the list and then click on the "Current" button and then click the "OK" button to finish. The selected layer is now the current layer and it's properties are displayed on the Object Properties toolbar.

Most experienced AutoCAD users change the current layer so frequently that the above method starts to seem very long winded. It is much quicker and therefore more efficient to set the current layer directly from the Object Properties toolbar using the "Layer Control" drop-down list. To set the current layer, click on the down arrow next to the Layer Control window to reveal the layer list. Simply click on the name of the layer you wish to make current. If the layer name is not visible because the list is quite long, scroll down the list until you see it. The drop-down list only displays 10 layers at a time. As a beginner, you may feel that this is quite a lot but a complex and well structured drawing may have 50 or 100 layers.

Toolbar
Pull-down	not available
Keyboard	AI_MOLC

There is an even quicker way to change the current layer providing you know which layer objects are on. You can use the Make Object's Layer Current command to set the current layer to the layer of any picked object.

Command Sequence

Select Make Object's Layer Current from the Object Properties toolbar.
When AutoCAD prompts
Select object whose layer will become current:
pick the object you know to be on the required layer. If you miss the object you are trying to select, the command is automatically canceled

AutoCAD confirms the action by writing to the command line
LAYER NAME is now the current layer.
You will also see the layer details change in the Object Properties toolbar. With a bit of practice and a good awareness of the layers you are using, this command can save lots of time.

Setting the Colour of a Layer on Autocad

2012-01-12T19:28:00.000-08:00

Setting the Colour of a Layer on Autocad

It is often convenient to set the layer colour when the layer is created, although this can be done at any time. The layer colour can be changed as many times as you like. Each time it is changed, any objects on that layer will change to the new colour, providing their colour is set to "ByLayer".

To set a layer colour, open the Layer; Linetype Properties dialogue box, click on and then click on the colour icon in the layer list associated with the layer you want. Notice that all layers have their own colour icon and that this changes to display the layer colour. Clicking on the icon brings up the Select Color dialogue box, shown on the right.

You can select any of the 255 standard AutoCAD colours by picking on the colour palette or by entering the colour name or number in the text edit box. When you have selected the colour you want, click on the "OK" button to set the colour. AutoCAD uses only 255 colours plus the drawing background colour, irrespective of the capabilities of your video display.

Assigning different colours to your layers will make working with complex drawings much easier. You will be able to see at a glance what a particular line represents. For example, your construction lines may be on a layer called "Construction" and have the colour yellow. This will visually differentiate these lines from lines on other layers with different colours.

Object Selection Modes

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Toolbar	not available
Pull-down	ToolsOptions…
Keyboard	DDSELECT

The Selection tab of the Options dialogue box (extract shown on the right) can be used to control many of the settings that have been discussed above and some that have not. In general it is advisable not to change any of the default settings unless you have good reason to do so.
Noun/Verb Selection allows you to select objects either before or after starting a command when it is checked.
Use Shift to Add, does just that when checked. The default is to remove objects when shift picking, as described above.
Press and Drag enables selection windows to be defined by picking and then dragging the mouse when checked. The default method for defining a selection window is to use two pick points.
Implied Windowing enables this type of selection when checked. See "Implied Windowing" above for details.
Object Grouping enables a group of objects to be selected by picking only one of the objects in the group when it is checked.
Associative Hatch causes a hatch boundary to be selected along with the hatch when it is checked.

Pickbox Size

You can also use the Selection tab of the Options dialogue box to change the pickbox size. Use the slider bar to increase or decrease the size. The larger the size of the pickbox the wider the area in which AutoCAD looks for objects. Generally the pickbox is better set to a smaller size to make picking more accurate. The default setting works very well and it is unlikely that you will need to change it.

Object Sorting Methods

Object sorting methods are controlled from the User Preferences tab on the Options dialogue box, from the pull-down menu. The object Sorting Methods section of the dialogue is shown on the right. These options enable you to optimise the way objects are selected with respect to different operations. Objects will be added to selection sets in the order in which they appear in the drawing database for each method that is checked. Although the "Plotting" and "PostScript Output" methods are the only ones set by default, it is often advantageous also to check the "Object Selection" method so that more recent objects are selected before older ones for general drafting. Since processing time is increased for each additional method selected, it would also be advantageous to uncheck the "PostScript Output" method unless you intend to use PostScript output, of course.

Create a Drawing

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Start a new drawing, click on and select "Start from Scratch" from the Create New Drawing dialogue box.
Use the Layer command, from the toolbar or FormatLayer… from the pull-down menu to create two new layers called "Construct" and "Boundary". Set the Construct layer colour to Green and the Boundary layer colour to Red. Set the current layer to "Construct".

Note: If you need more information about layers, see the "Object Properties" tutorial.

Draw a selection of objects, lines, polylines, ellipses etc. including several circles.
Set the current layer to "Boundary" using the Object Properties toolbar.
Draw some more circles.
Now you are going to erase just the circles on the Construct layer, so start the ERASE command, from the Modify toolbar or ModifyErase from the pull-down menu.

Compile the Filter

At the "Select objects" prompt enter 'filter. The apostrophe is very important, it tells AutoCAD that you want to use a command transparently.
When the Object Selection Filter dialogue box appears, select "Layer" from the drop-down list. The list is arranged alphabetically so you will need to scroll down the list to find it. When you have selected "Layer", click on the "Select…" button. The Select Layer(s) dialogue box appears, select "Construct" from the list and click the "OK" button. You are now returned to the Object Selection Filter dialogue box, click the "Add to List" button, your layer selection is added to the list which now displays "Layer = Construct".
Next, select Circle from the drop-down list and click the "Add to List" button. "Object = Circle" is added to the list below the Layer entry. You have now completed the filter list.

Apply the Filter

Click on the Apply button. The dialogue box disappears and you are returned to the "Select objects" prompt. The principle behind the filter list you have just compiled is that when applied to a selection, all objects which do not match the listed criteria will be filtered out. The simplest way to apply this filter to the whole drawing is to use the All selection option. Enter all at the prompt. All objects are selected but the filter ensures that all objects except the circles on the Construct layer are filtered out.All the circles on the Construct layer are highlighted to indicate that they are selected. and you are returned to the "Select objects" prompt.
Enter at the prompt, AutoCAD responds:
Exiting filtered selection.
You now see the "Select objects" prompt again because you can add objects to the selection set without them being filtered. Enter again to complete the command. The green circles are erased, leaving all other objects unaltered.

This whole process may seem very long-winded but when you have to make this type of selection on a complex drawing you will thank your lucky stars that the Filter command exists. However, if your selection requirements are more reasonable, try the Quick Select command as an

Object Selection Filters

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It may sometimes happen that you need to create a selection set of objects based upon one or more of their properties. For example, you may want to select all objects on a particular layer or more particularly, you may even want to select all circles on that layer. This type of selection is relatively easy with the Quick Select command discussed above. However, what if you wanted to select all green circles and lines on a particular layer? As good as Quick Select is, it cannot create selections from so many parameters. Fortunately AutoCAD provides a method to filter objects based upon a wide range of selection criteria.

Toolbar	not available
Pull-down	not available
Keyboard	FILTER or FI

An AutoCAD drawing is simply a database of objects and their properties. Using the Filter command you can define a query just like you would in a database. If you look at the Object Selection Filters dialogue box, shown above, you will see that a filter has been defined that will select all circles on the "Construct" layer.

To create a filter, click the arrow on the drop-down list in the Select Filter area and select the object type or property you would like to add to the filter list. Click on the "Add to List" button. You can add as many object types or properties to the list as you like. Having defined a filter list you can either use it as a one-off or you can save it as a named filter by typing a name in the Save As edit box and then clicking the "Save As" button. Your named filter will then be added to the Named Filters drop-down list and you can use it again at any time.
Although you can create filters using the Filter command from the command prompt, you will mostly want to use it during the course of a selection operation. Fortunately, the Filter command can be used transparently. This means that it can be used whilst another command is still running. To get an idea how this might work, follow the example below.

Quick Select

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The selection tools described in the Object Selection tutorial are fine if you only need to pick a few objects at a time or if you can easily see the objects you want to select. Sometimes though, your selection requirements may not be quite so simple. AutoCAD enables you to create selection sets by building database style queries that can make complex selections really quick and accurate. This tutorial describes the use of AutoCAD's advanced selection tools and how the selection options can be configured for better selection efficiency.

Quick Select

Toolbar	not available
Pull-down	ToolsQuick Select…
Keyboard	QSELECT

Quick Select made it's debut in AutoCAD 2000 and is designed to help users make complex selections quickly. It is also designed to be a simplified version of the Filter command, detailed below. Quick Select allows you to make selections based upon object properties. Say, for example, that you needed to select all circles on a layer called Water. Quick Select can help you do this. If you look at the dialogue box below, you will see that there are a number of parameters to set. To select all circles on the Water layer, you would make the settings shown in the dialogue box.

Let's have a closer look at the selection parameters in the Quick Select dialogue box. As with all dialogue boxes, it is important to move methodically through the various parameters. It is even more important in this case because the choices you make at the beginning of the process will affect the options available to you later. Start at the top of the dialogue with "Apply to" and work your way down.

The "Apply to" parameter can be used to cause the selection to be made from the entire drawing or from a selected part of the drawing. Use the Select objects button to create a selection set from which your more detailed selection will be made.
The "Object type" parameter allows you to select objects such as circles, lines etc. The drop-down list contains an inventory of all the different object types in the current drawing. If your selection is to be made from more that one object type, select "Multiple". Note that this parameter only allows you to select one object type or all objects. This is one limitation of Quick Select, although you can append selections to create compound selection sets, see below. However, if you want to make complex selections based upon multiple selection criteria, you may be better of using the more advanced features of the Filter command described below.
The "Properties" parameter allows you to specify which paricular property of an object type to apply to the selection. For example, circle properties include radius, diameter and circumference in addition to the standard object properties like layer and colour. So you could select all circles with with a particular radius or all circles on a particular layer.
The "Operator" parameter determines how the value is applied to the selection. For example, using the equals option with a circle radius and a value set to 24 would mean all circles with a radius of 24 are selected. However, other options available for the operator parameter allow you to select all circles of radius less that 24 or greater than 24 or even all circles except those with a radius of 24. Pretty amazing huh?
The "Value" parameter is used to specify the value of the property you have already chosen. For example, if you had specified Circle and Radius as your object type and property, you might enter "24" as a value. All circles with a radius of 24 would be selected. Or if you had specified Circle and Layer as your object type and property, you could select a layer name such as "Water". In this case, all circles on the layer called Water would be selected.

Finally, using the "How to apply" box, you have the option to have the selected objects either included or excluded from the new selection set. In addition, you can also have this selection appended to the current selection set. The "Append to current selection set" option is particularly useful because it means that you can use Quick Select repeatedly to build up compound selections. For example, you could use Quick Select to select all blue circles and then use it again to select all blue lines. Appending the blue lines selection to the blue circles selection would mean that you end up with a selection of all blue lines and circles.

As you can see, this is a very powerful tool and takes a little time to get used to. However, it is well worth making the effort as it can drastically improve your drawing efficiency. For your convenience, Quick Select is also available from the right-click context menu.

Modifying Object: The Explode Command

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Toolbar	Modify
Pull-down	ModifyExplode
Keyboard	EXPLODE

The Explode command is used to "explode" single objects back to their constituent parts. In other words, the command is used to return blocks, polylines etc. (which may be composed of a number of component objects) back to their individual component parts. The change has no visible effect.

Tips & Tricks

Always look at the command line for guidance when you are learning new AutoCAD commands. The command line will prompt you for information and this is the easiest way to find out how a new command works. This is especially true for the more complicated commands like Trim and Extend.
The command line window displays 3 lines of text by default. You can change this by clicking and dragging the top of the window frame. When you are starting with AutoCAD you may like to see more than 3 lines. The illustration below shows the command line window increased in size to 6 lines.

The command line can also be displayed as a floating text window. The AutoCAD text window is displayed by pressing the F2 key on the keyboard. See Function Keys on the Drawing Aids tutorial for more details.
You can control the way text is mirrored using the MIRRTEXT variable.
You can use the Fillet command with a radius of zero to trim intersecting lines back to their intersection. Of course, you could also achieve this effect with the Trim command but if you have a number of operations to complete, the Fillet method is much quicker.
When using the Trim and Extend commands, hitting when prompted to "Select cutting edges" and "Select boundary edges" respectively will automatically select all valid cutting or boundary edges on the screen. This can be a real time saver if you have a complicated set of edges to select.

Modifying Object: The Fillet Command

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Toolbar	Modify
Pull-down	ModifyFillet
Keyboard	FILLET	short-cut	F

The Fillet command is a very useful tool which allows you to draw an arc between two intersecting lines or adjacent polyline segments. You first need to use the command to set the required radius and then a second time to select the two lines.

Command Sequence

Command: FILLET
Current settings: Mode = TRIM, Radius = 10.0000
Select first object or [Polyline/Radius/Trim]: R
Specify fillet radius <10.000>: 25
Select first object or [Polyline/Radius/Trim]: (pick P1)
Select second object : (pick P2)

The Fillet command can also be used to fillet arcs and circles. The "Polyline" option also allows you to fillet all vertices of a polyline with a single command. It's worth experimenting with this command, it can save you lots of time and enables you to construct shapes which otherwise would be quite difficult.

For example, you can easily create the lozenge shape shown on the right from a simple rectangle. Since AutoCAD rectangles are just closed polylines, you can use the Polyline option of the Fillet command to fillet all polyline vertexes simultaneously. Try this for yourself; draw a rectangle and then follow the command sequence below.

Command Sequence

Command: FILLET
Current settings: Mode = TRIM, Radius = 10.0000
Select first object or [Polyline/Radius/Trim]: P
Select 2D polyline: (pick P1)
4 lines were filleted

Tip: Make sure that the radius you specify will fit the objects you select, otherwise the fillet command will not work.

Modifying Object: The Chamfer Command

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Toolbar	Modify
Pull-down	ModifyChamfer
Keyboard	CHAMFER	short-cut	CHA

The Chamfer command enables you to create a chamfer between any two non-parallel lines as in the illustration below or any two adjacent polyline segments. Usually, the Chamfer command is used to set the chamfer distances before drawing the chamfer. Follow the command sequence below where the chamfer distances are changed to 20 before the chamfer is made.

Command Sequence

Command: CHAMFER
(TRIM mode) Current chamfer Dist1 = 10.0000, Dist2 = 10.0000
Select first line or [Polyline/Distance/Angle/Trim/Method]: D (to set distances)
Specify first chamfer distance <10.0000>: 20 (enter required distance)
Specify second chamfer distance <20.0000>: (first distance value or enter a different value)
Select first line or [Polyline/Distance/Angle/Trim/Method]: (pick P1)
Select second line: (pick P2)
The chamfer is made and the command ends.

Notice from the command sequence that there are a number of options which can be used to control the way the Chamfer command behaves. The Polyline option can be used to chamfer all vertexes of a polyline simultaneously. The Distance option allows you to specify the two chamfer distances. Angle allows the angle between the first line and the chamfer to be specified. Trim is used to control whether the original lines are trimmed to the chamfer or remain as they are. Finally, Method is used to toggle the command between Distance and Angle mode. When Angle mode is used, the chamfer is defined using one distance and an angle rather than two distances.

Modifying Object: The Break Command

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Toolbar	Modify
Pull-down	ModifyBreak
Keyboard	BREAK	short-cut	BR

The Break command enables you to break (remove part of) an object by defining two break points. In the illustration below, a corner of a rectangle has been removed. The Break command can be used with lines, polylines, circles, arcs ellipses, splines, xlines and rays. When you break an object, you can either select the object using the first break point and then pick the second break point, or you can select the object and then pick the two break points.

Command Sequence

Command: BREAK
Select objects: (select the object using the first break point, P1)
Specify second break point or [First point]: (pick the second break point, P2)
The section of the object is removed and the command ends.

Sometimes you may want to select the object first and then specify the two break points. If this is the case, use the "First point" option to specify the first break point. By default, AutoCAD assumes that the point used to select the object is the first break point. This is often confusing for new users.

It may sometimes be necessary to break a line into two without removing any part of it. In this case, simply pick the first and second break points in the same position.

Modifying Object: The Extend Command

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Toolbar	Modify
Pull-down	ModifyExtend
Keyboard	EXTEND	short-cut	EX

This command extends a line, polyline or arc to meet another drawing object (known as the boundary edge). In the illustration on the right, two lines (red) are extended to meet another line (cyan) which forms the boundary edge. This command works in a similar way to the Trim command, described above. Two selections are made, one for the boundary edge(s) and one for the object(s) to extend.

Lines and other objects can be extended in one of two directions. In the illustration on the right, the red line could be extended either to the right or to the left. You can tell AutoCAD in which direction to extend by picking a point to the right or left of the midpoint respectively. AutoCAD does not intuitively know where the boundary edge lies so you must explicitly indicate the direction of extension by picking either one side or other of the midpoint.

Draw the lines as shown in the illustration and follow the command sequence below.

Command Sequence

Command: EXTEND
Current settings: Projection=UCS Edge=None
Select boundary edges ... Select objects: (select the boundary edge, P1)
Select objects: (to end boundary edge selection)
Select object to extend or shift-select to trim or [Project/Edge/Undo]: (pick the object which you want to be extended, P2)
Select object to extend or shift-select to trim or [Project/Edge/Undo]: (pick another object which you want to be extended, P3)
Select object to extend or shift-select to trim or [Project/Edge/Undo]: (to end)

Sometimes you may get the message "Object does not intersect an edge" or "No edge in that direction". If this happens it means that you are either picking the wrong end of the object or the object you are trying to extend will not meet the boundary edge. The solution is either to pick near the end you want to extend or to move the boundary edge so that the extended line will intersect with it.

Using Edgemode

If the line you are trying to extend does not intersect with the boundary line, you can use the "Edge" option to toggle Edgemode to "Extend" (the default is "No Extend"). When the Extend command is set to Extend Mode, the objects being extended will extend to an imaginary line through the boundary edge, irrespective of whether the extended object actually intersects with the boundary edge. This is particularly useful and can save lots of time.

The illustration on the left shows the result of extending a line (red) to a boundary edge (cyan) with Edgemode set to "Extend". The same process would have resulted in an error message if Edgemode had been set to "No Extend". To get a better understanding of how this works, draw the two lines as shown in the illustration and try to extend them using the default settings. When you have done that, follow the command sequence below.

Command Sequence (Edgemode)

Command: EXTEND
Select boundary edges: (Projmode = UCS, Edgemode = No extend) Select objects: (select the boundary edge, P1)
Select objects: (to end boundary edge selection)
Select object to extend or shift-select to trim or [Project/Edge/Undo]: E (to use the Edge option)
Enter an implied edge extension mode [Extend/No extend] : E (to set Edgemode to Extend)
Select object to extend or shift-select to trim or [Project/Edge/Undo]: (pick the object to be extended, P2)
Select object to extend or shift-select to trim or [Project/Edge/Undo]: (to end)

Notice that the current value of Edgemode is always displayed on the command line when you start the Extend command. The Edge option can also be used with the Trim command to enable trimming to cutting edges which do not actually intersect the object to trim. Edgemode is a system variable, so any change to its value will affect both the Trim and Extend commands.

See the Lengthen command for more ways to extend and trim objects.

Shift Selection with Trim & Extend

You may have noticed during the command sequences for the Trim and Extend commands that you have the option to "shift-select". This feature is new to AutoCAD 2000i and it enables you to extend while using the Trim command and to trim while using the Extend command. These two commands are very closely related and you often need to trim and extend objects at the same time. If you are a beginner with AutoCAD it may be a good idea to avoid this feature initially, the Trim and Extend commands can be tricky to get to grips with in any case. However, do remember this feature because it is a great time saver.

Modifying Object: The Trim Command

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Toolbar	Modify
Pull-down	ModifyTrim
Keyboard	TRIM	short-cut	TR

The Trim command can be used to trim a part of an object. In order to trim an object you must draw a second object which forms the "cutting edge". Cutting edges can be lines, xlines, rays, polylines, circles, arcs or ellipses. Blocks and text cannot be trimmed or used as cutting edges. The illustration on the right shows the Trim command in action. The red square and circle have been drawn using the Polygon and Circle commands respectively. In order to trim these objects, a line has been drawn (cyan in the illustration), this forms the cutting edge. The Trim command, unlike most other modify commands requires that two separate object selections are made. The cutting edges are selected first (there can be one or more) and then the objects to be trimmed are selected. In the example above, the line is selected first because it forms the cutting edge and then the square and circle are selected.

The Trim command is slightly more complicated than many other modify commands. To get a better understanding of how it works, draw a square, circle and line as illustrated above and then follow the command sequence below. Don't forget to watch the AutoCAD command line at each stage of the process.

Command Sequence

Command: TRIM
Current settings: Projection=UCS Edge=None
Select cutting edges ... Select objects: (select the cutting edge, P1)
Select objects: (to end cutting edge selection)
Select object to trim or shift-select to extend or [Project/Edge/Undo]:(pick the part of the square which you want to trim, P2)
Select object to trim or shift-select to extend or [Project/Edge/Undo]: (pick the circle, P3)
Select object to trim or shift-select to extend or [Project/Edge/Undo]: (to end)

Notice that at each trimming step you are given the option to undo the previous trim. This can be very useful if you inadvertently pick the wrong object.

In the above example, when the objects were trimmed, both pick points were made to the right of the cutting edge, resulting in the removal of that part of the objects to the right of the cutting edge. Obviously, the portion of square and circle to the left of the cutting edge could have been removed by picking to the left of the cutting edge. Also, you may not have noticed it, but by trimming a circle you have created an Arc object. This makes no visible difference but the object type has changed.

Modifying Object: The Lengthen Command

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Toolbar	Modify
Pull-down	ModifyLengthen
Keyboard	LENGTHEN	short-cut	LEN

The Lengthen command can often be used instead of either the Trim or Extend commands. Indeed the end result is exactly the same. The Lengthen command can be used to either lengthen or shorten Lines, Arcs, open Polylines, elliptical Arcs and open Splines without the use of cutting or boundary edges.

Command Sequence

Command: LENGTHEN
Select an object or [DElta/Percent/Total/DYnamic]: DY
Select an object to change or [Undo]: (select a line or arc)
Specify new end point: (pick new end point)
Select an object to change or [Undo]: (to end)

The command sequence above demonstrates the use of the Dynamic Lengthen option which is probably the most useful for general purpose drafting. However, the other options are worth getting to know because they can save lots of time and effort.

The Total option allows you to change the total length of a line to any value that you specify. The Percent option allows you to change a line length using a percentage. For example, a value of 50 will result in a line one half the length of the original and a value of 200 will result in a line twice the length of the original. The Delta option can be used to extend or reduce the endpoint of a line by a given distance. The endpoint affected by the change is the one closest to the pick point when the object selection is made.

Modifying Object: Stretching with Grips

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Although the Stretch command can be very useful, it has largely been superseded by the use of "Grips" which allow this sort of modification to be made much more intuitively.

To stretch an object using grips, simply select the object by clicking on it (you can do this without starting a command). The object becomes highlighted and small square grips appear at each vertex and various snap points, depending upon the object type. Click a grip to activate it and click again to reposition it. When you have completed your modifications, use the Escape key (Esc) at the top left of your keyboard to deselect the object and release grips.

Modifying Object: The Stretch Command

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Toolbar	Modify
Pull-down	ModifyStretch
Keyboard	STRETCH	short-cut	S

The Stretch command can be used to move one or more vertices of an object whilst leaving the rest of the object unchanged. In the example below, a rectangle has been stretched by moving one vertex to create an irregular shape.

Command Sequence

Command: STRETCH
Select objects to stretch by crossing-window or crossing-polygon...
Select objects: (pick first point of crossing window)
Specify opposite corner: (pick second point of window)
Select objects: (to end selection)
Specify base point or displacement: (pick base point)
Specify second point of displacement: (pick second point)

To select vertices to stretch, you must use a crossing window or polygon. See the "Object Selection" tutorial for details of these selection methods.

Modifying Object: The Scale Command

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Toolbar	Modify
Pull-down	ModifyScale
Keyboard	SCALE	short-cut	SC

The Scale command can be used to change the size of an object or group of objects. You are prompted for a pick point about which the selection set will be scaled. Scaling can then be completed by picking a second point (not always easy because it can sometimes be difficult to precisely control the scaling) or by entering a scale factor at the keyboard. For example a scale factor of 2 will double the size of the objects in the selection set and a factor of 0.5 will half them.

Command Sequence

Command: SCALE
Select objects: (pick objects to be scaled, P1)
Select objects: (to end selection)
Specify base point: (pick base point, P2)
Specify scale factor or [Reference]: (pick second point, P3 or enter scale factor)

In the example shown above, the original tree symbol has been enlarged by dynamically scaling it using pick points to determine the change in scale. If you want to scale an object precisely, it is much easier to enter a scale factor using the keyboard.

Note that the position of the new sized tree symbol is determined by the location of the base point. The base point, P2 has been picked to the upper right of the centre of the tree which resulted in the centre of the tree shifting to a lower left position. If the base point had been picked in the centre of the tree symbol, the tree would have remained in the same position. In theory the base point can be any point in the drawing area but for ease of control it is best to choose a known point so that the results are obvious.

Modifying Object: The Rotate Command

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Toolbar	Modify
Pull-down	ModifyRotate
Keyboard	ROTATE	short-cut	RO

The Rotate command allows an object or objects to be rotated about a point selected by the user. AutoCAD prompts for a second rotation point or an angle which can be typed at the keyboard.

Command Sequence

Command: ROTATE
Current positive angle in UCS: ANGDIR=counterclockwise ANGBASE=0
Select objects: (pick object to rotate, P1)
Select objects: (to end selection)
Specify base point: (pick base point, P2)
Specify rotation angle or [Reference]: (pick second point, P3 or enter angle)

Remember, by default, AutoCAD angles start at 3 o'clock and increase in an anti-clockwise direction. The "ANGDIR" and "ANGBASE" variables remind you of this. If you want to rotate in a clockwise direction you can enter a negative angle by using a minus sign.

Note: You can change the angle direction and the base angle using the Units command, FormatUnits… from the pull-down menu. Click the "Clockwise" check box to change the direction and click the "Direction…" button to set the base angle.

Modifying Object: The Move Command

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Toolbar	Modify
Pull-down	ModifyMove
Keyboard	MOVE	short-cut	M

The Move command works in a similar way to the Copy command except that no copy is made, the selected object(s) is simply moved from one location to another.

Command Sequence

Command: MOVE
Select objects: (pick object to move, P1)
Select objects: (to end selection)
Specify base point or displacement: (pick P2)
Specify second point of displacement or : (pick P3)

Note that as with the Copy command, the two pick points, P2 and P3 are used only to indicate the distance and direction of movement.

Modifying Object: The Array Command

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Toolbar	Modify
Pull-down	ModifyArray
Keyboard	ARRAY	short-cut	AR

The Array command makes multiple copies of selected objects in a rectangular matrix (columns and rows) or a polar (circular) pattern. This command has been completely transformed in AutoCAD 2000i. It is now completely dialogue box driven with the option to see a preview of the array before it is created. You can also now create rectangular arrays at a user specified angle angle. This constitutes a major improvement in usability.

The Rectangular Array

The illustration on the right shows the results of a rectangular array with two columns an three rows. The distance between rows is indicated with the dimension DR and between columns with DC. When creating rectangular arrays it is important to remember that new rows are created above the original object and new columns are created to the right of the original object. The resulting array is, therefore, always created with the original object in the bottom left hand position with respect to the current co-ordinate system. In the illustration, the original object is shown in cyan and the new objects in red. It is possible to create arrays which do not align with the World Co-ordinate System by setting a User Co-ordinate System first. See the UCS tutorial for details.

Try creating this array yourself. First, draw a rectangle 20 drawing units wide and 10 drawing units tall. To do this, start the rectangle command DrawRectangle from the pull-down menu. When you are prompted to pick a point, pick somewhere in the lower left quarter of the drawing area. Then, when you are prompted for a second point, enter the relative cartesian co-ordinate @20,10. You have now drawn a rectangle at the right size. See the Using Co-ordinates tutorial for more information on drawing with co-ordinates.

Now start the Array command.First of all, make sure that the Rectangular Array radio button is selected and that you are looking at the Rectangular Array dialogue box and now follow the steps below:

Click the Select objects button. The dialogue box will temporarily disappear enabling you to select the rectangle you just drew. Press the Return button on your keyboard to complete the selection. You are now returned to the dialogue box and the message immediately below the Select Objects button should read "1 objects selected".
Enter the number of rows required in the Rows edit box. For this example, enter the value "3". Notice that the schematic preview on the right hand side of the dialogue box updates to reflect the values you are entering.
Enter the number of columns required in the Columns edit box. Enter the value "2".
Enter the row offset in the Row Offset edit box. This is the distance DR in the illustration above. Note that tis is not the distance between rows. In this example, our rectangle is 10 units high and we will enter a row offset of 15. The result will be a 5 unit gap between rectangles.
Enter the column offset in the Column Offset edit box. The same parameters apply as for the row offset. Enter a value of 25 to give a 5 unit gap between our rectangles.
Click on the Preview button. Once again, the dialogue box disappears and the specified array is temporarily drawn so that we can preview it. We are now offered 3 choices. If the array isn't quite right, click the Modify button to return to the Array dialogue box. If you are happy with the array, click the Accept button, the array will be permanently drawn and the command is ended.

You should now have an array that looks similar to the one in the illustration above consisting of 6 rectangles arranged in 3 rows and 2 columns. As you can se, this command is very powerful and can save lots of time if used carefully.

The Polar Array

The polar array works in a similar way to the rectangular array. The main difference is that rather than specifying the number and offset for rows and columns, you must specify a center point and the total number of objects in the array (including the original object).

You can try this for yourself by drawing another rectangle as described above. This time, though, locate the rectangle in the centre top half of the drawing area. Now, start the Array command, click the Polar Array radio button and follow the steps below:

Click the Select objects button. The dialogue box will temporarily disappear enabling you to select the rectangle you just drew. Press the Return button on your keyboard to complete the selection. You are now returned to the dialogue box and the message immediately below the Select Objects button should read "1 objects selected".
Specify the center point for the array. This is the point C in the illustration below. You can do this by entering x and y co-ordinates into the appropriate edit boxes if you know what these values should be. However, this is rarely the case and most often you will want to click the Pick Center Point button to pick a point from the drawing area. Pick a point somewhere below the rectangle you have just drawn.
Enter a value for the total number of items. For this example, enter the value "6". Notice that once again, the schematic preview updates to reflect the values you have entered.
Make sure that the Rotate items as copied checkbox is checked.
Click on the Preview button. Once again, the dialogue box disappears and the specified array is temporarily drawn so that we can preview it. We are now offered 3 choices. If the array isn't quite right, click the Modify button to return to the Array dialogue box. If you are happy with the array, click the Accept button, the array will be permanently drawn and the command is ended.

The array you have just drawn should look something like the one illustrated below, left. Take some time to play around with the other options in the Array dialogue box to see what they can do.

The illustration above shows the results of a polar array using an original rectangle (cyan) copied six times about a centre point C, through an angle of 360 degrees (full circle). The only difference between the array on the left and the one on the right is that the Rotate items as copied checkbox was not checked in the right hand example.

All new objects created with the Array command will inherit the object properties of the original object. See the "Object Properties" tutorial for information on object properties.

Modifying Object: The Offset Command

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Toolbar	Modify
Pull-down	ModifyOffset
Keyboard	OFFSET	short-cut	O

Offset is probably one of the most useful commands for constructing drawings. The Offset command creates a new object parallel to or concentric with a selected object. The new object is drawn at a user defined distance (the offset) from the original and in a direction chosen by the user with a pick point. You can offset lines, arcs, circles, ellipses, 2D polylines, xlines, rays and planar splines.

Command Sequence

Command: OFFSET
Specify offset distance or [Through] <1.0000>: 10 (specify distance)
Select object to offset or : (select object, P1)
Specify point on side to offset: (pick direction, P2)
Select object to offset or : (to end or select another object to offset)

In the illustration below, a line (cyan) has been offset to the right through a distance "Offset" by picking a point to the right of the original line. The result is a new line (red) to the right of the original.

Circles can be offset inside or outside of themselves to create a new circle which is concentric (has the same centre point) with the original circle. In the illustration, a new circle (red) has been created outside of the original by picking a point outside of the original circle. The radius of the new circle is the offset distance "Offset" plus the radius of the original circle.

In the illustration above, the new objects and original objects are shown in different colours for clarity. In reality, offset objects inherit their object properties from the original object. See the "Object Properties" tutorial for details.

Modifying Object: The Mirror Command

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Toolbar	Modify
Pull-down	ModifyMirror
Keyboard	MIRROR	short-cut	MI

The Mirror command allows you to mirror selected objects in your drawing by picking them and then defining the position of an imaginary mirror line using two points.

Command Sequence

Command: MIRROR
Select objects: (pick object to mirror, P1)
Select objects: (to end selection)
Specify first point of mirror line: (pick P2)
Specify second point of mirror line: (pick P3)
Delete source objects? [Yes/No] : (for No to keep the original object)

Notice that in the command sequence above, pressing the key when asked whether to "Delete source objects?" resulted in a "No" response. This is because "No" is the default option. AutoCAD always shows the default option within triangular brackets, in this case "". Many AutoCAD commands offer default options. They are usually the most commonly used and you need only right-click and select "Enter" from the menu or press on the keyboard to accept them.

In order to create perfectly horizontal or vertical mirror lines use Ortho. For more information on the use of Ortho and other drawing aids, see the "Drawing Aids" tutorial.

Modifying Object:The Copy Command

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Toolbar	Modify
Pull-down	ModifyCopy
Keyboard	COPY	short-cut	CP

The Copy command can be used to create one or more duplicates of any drawing object or objects which you have previously created. Copy is a very useful and time-saving command because you can create very complex drawing elements and then simply copy them as many times as you like.

Command Sequence

Command: COPY
Select objects: (pick object to copy, P1)
Select objects: (to end selection)
Specify base point or displacement, or [Multiple]: (pick P2 or M for multiple copies)
Specify second point of displacement or : (pick P3)

The multiple option allows you to create additional copies of the selected object(s) by picking as many new points as you like. To end a multiple copy, just hit the key.

Notice that the "Base point", P2 and the "Second point", P3 do not have to be picked on or near the object. The two points are simply used to indicate the distance and direction of the copied object from the original object.

The Erase Command

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Toolbar	Modify
Pull-down	ModifyErase
Keyboard	ERASE	short-cut	E

The Erase command is one of the simplest AutoCAD commands and is one of the most used. The command erases (deletes) any selected object(s) from the drawing. Remember you can always get deleted objects back by typing U to undo, from the Standard toolbar or by using the OOPS command.

Command Sequence

Command: ERASE
Select objects: (pick an object to erase)
Select objects: (to end the selection and erase the object)

If you simply want to erase the last object you created you can type L at the "Select objects" prompt. The last object will be highlighted and you can then select more objects or to end the command. See the "Object Selection" tutorial for more information on selecting objects.

Introduction Modifying Objects

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AutoCAD drawings are rarely completed simply by drawing lines, circles etc. Most likely you will need to Modify these basic drawing objects in some way in order to create the image you need. AutoCAD provides a whole range of modify tools such as Move, Copy, Rotate and Mirror. As you can see, the command names are easily understandable. However, the way these commands work is not always obvious. This tutorial is designed to show you how all of the Modify commands work. If you just need information quickly, use the QuickFind toolbar below to go straight to the information you need or select a topic from the contents list above.

As is usual with AutoCAD, the Modify tools can be accessed in one of three ways, from the keyboard, from the pull-down menu and from the toolbar. All of the Modify tools are available from the Modify pull-down and the Modify toolbar. In each section below, the toolbar, pull-down and keyboard options are given. The method you choose is entirely up to you. Ultimately you will use the method that you feel most comfortable with or the one you find most efficient. AutoCAD allows great flexibility and there aren't any right or wrong ways of working. That said, it should be pointed out that the use of toolbars in AutoCAD is almost always quicker than any other method.

The Modify toolbar is usually displayed by default but if it is not already displayed, you can display it using the TOOLBAR command, ViewToolbars… from the pull-down menu. When the Toolbar dialogue box (shown above) appears, simply check the box next to "Modify" in the toolbars list. Many AutoCAD users work with the Modify toolbar permanently docked on their screen because it gives one-click access to all of the commands, making the drawing process much more efficient.

Crossing Polygon Selection

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The Crossing Polygon option can be used in exactly the same way as the Window Polygon option but it has the same selection criteria as the Crossing Window option, i.e. objects will be selected if they fall entirely within or touch the polygon boundary. This option is invoked by typing CP at the "Select objects" prompt.

Note: Lines, polygons and windows drawn using the selection options do not exist as drawing objects. Once the selection has been made they disappear.

Using a Previous Selection

AutoCAD always remembers the last selection set you defined. This is very useful because you may need to make a number of changes using different commands to the same group of objects. In order to re-select the last selection set you can use the Previous option. The previous option is invoked by typing P at the "Select objects" prompt.

Selecting the Last Object

You can select the last object created by entering L at the "Select objects" prompt.

Object Cycling

When drawings become complicated it is sometimes difficult to select the particular object you want because it is either very close to or overlies another object. In such a case it may happen that the other object is selected and not the one you want. Object cycling is designed to overcome this problem. If you make a pick whilst holding the Control (Ctrl) key down, AutoCAD will respond with "". If you continue to pick, each object near the pick point is highlighted in rotation. Just keep picking until the object you want is highlighted, then right-click or , AutoCAD responds "", the required object is added to the selection set and you can continue to select more objects as normal.

Adding and Removing Objects

AutoCAD provides two methods for adding and removing objects to and from a selection set. As you know, objects can be added to a selection set simply by picking them or by using one of the methods outlined above. You can remove selected objects from a selection set just as easily by shift picking. If you hold the Shift key down on the keyboard while picking a selected object, that object will be deselected (removed from the current selection set). You can tell when a selected object has been deselected because it is no longer highlighted. You can remove more than one object at a time by holding down the Shift key while using implied windowing. However, none of the other selection options which require keyboard input will work using the shift pick method.

If you need to remove a more complex selection from the current selection set you should use the Remove option to switch to Remove mode. If you enter R at the "Select objects" prompt, AutoCAD will respond:

Remove objects:

Objects now picked or selected using any of the above methods will be removed from the current selection set. When you have finished removing objects, you can return to Add mode by entering A at the "Remove objects" prompt.

You can use any combination of picking, selection options and add/remove modes to define your selection set. Once you are happy that you have selected all the objects you need, just hit to complete the selection process and to continue with the current command.

When you feel confident with the basic selection tools, have a look at the Advanced Selection tutorial to find out how to use AutoCAD's advanced selection tools for creating complex selection sets.

Tips & Tricks

When you are picking objects in a complex drawing, use the ZOOM command transparently to make object selection easier. All Zoom options selected from the toolbars are automatically transparent but if you invoke the command from the keyboard you will need to enter 'zoom.

Window Polygon Selection

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The Window Polygon option, invoked by typing WP is similar to the Window option except that you can define an irregular polygon shape within which objects will be selected. As with the Window option, only objects which fall entirely within the polygon will be selected.

Command Sequence

Command: (start one of the Modify commands)
Select objects: WP
First polygon point: (pick first point)
Specify endpoint of line or [Undo]: (pick second point)
Specify endpoint of line or [Undo]: (pick third point)
Specify endpoint of line or [Undo]: (pick another point or to end polygon selection)
Select objects: ( to complete the selection set or add more objects)

A polygon is formed by picking at least three points.

Fence Selection

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The Fence option allows you to draw a multi-segment line, like a Polyline. All objects which cross the fence will be selected. The Fence option is invoked by typing F at the "Select objects" prompt.

Command:
(start one of the Modify commands such as ERASE)

Command Sequence

Select objects: F
First fence point: (pick first point)
Specify endpoint of line or [Undo]: (pick second point)
Specify endpoint of line or [Undo]: (pick another point or to end fence selection)
Select objects: ( to complete the selection set or add more objects)

The Undo option

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It often happens that you inadvertently add objects which you don't want to a selection set during its compilation. When this occurs in the middle of a complicated selection it can be pretty annoying. Fortunately AutoCAD allows you to undo the last selection made during the compilation of a selection set. All you need do is enter U at the next "Select objects" prompt to remove the objects previously added.

Selecting All Objects

The All option is invoked by typing ALL at the "Select objects" prompt. You can use this option to select all the objects in the current drawing, no picking is required. Objects on Locked or Frozen layers are not selected but objects on layers which are simply turned off are selected.

Implied Windowing

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Although you can explicitly invoke the Window and Crossing Window selection boxes by entering W or C at the keyboard when prompted to "Select objects", in practice this is rarely done. Both of these selection options are so commonly used that AutoCAD provides a method of implied windowing so that you don't have to use the keyboard at all. You can test this out without using any command. If you pick a point in space on the graphic window, you will notice that AutoCAD automatically assumes that you want to define a selection window and uses the pick point as the first point of that window. If you move the cursor to the right of the pick point you will get a Window selection box (solid line). If you move the cursor th the left you will get a Crossing Window selection box (broken line). With a little bit of practice the use of implied windowing can make the whole drawing process very efficient and you will rarely find yourself having to explicitly invoke the window selection options from the keyboard.

Crossing Window Selection

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The Crossing Window option is invoked by typing C at the "Select objects" prompt and is a variation of the Window command. The command sequence is exactly the same but objects are selected which lie entirely within the window and those which cross the window border.


The Crossing selection box is shown as a rectangle with a broken line	Objects within and crossing the window will be selected

Window Selection

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The Window option is invoked by typing W in response to the "Select objects" prompt. Window allows you to define a rectangle using two points in exactly the same way as the RECTANGLE command. Once the window is defined, all objects which lie entirely within the window will be selected.


The Window selection box is shown as a rectangle with a solid line	Only objects entirely within the window will be selected

Command Sequence

Command: (start one of the Modify commands such as ERASE)
Select objects: W
First corner: (pick first corner)
Specify opposite corner: (pick second corner)
Select objects: (at this point you can either select more objects or to complete the selection set and continue with the current command.)

Draw Two Circles

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Draw two circles using the CIRCLE command, DrawCircleCenter, Radius from the pull-down menu or from the Draw toolbar. The size and position of the circles does not matter.

Command: CIRCLE
Specify center point for circle or [3P/2P/Ttr (tan tan radius)]: (pick a point in the middle of the drawing window)
Specify radius of circle or [Diameter] <8.3453>: (pick another point to define the circle circumference)
Command: CIRCLE
Specify center point for circle or [3P/2P/Ttr (tan tan radius)]: (pick the center point of the second circle)
Specify radius of circle or [Diameter] <37.9174>: (pick another point to define the circle circumference)

Erase the Two Circles

Erase the two circles using the ERASE command, ModifyErase from the pull-down or from the Modify toolbar.

Command: ERASE
Select objects: (place the pickbox over a circle circumference and left-click)
1 found
Select objects: (place the pickbox over the second circle circumference and left-click)
1 found
Select objects: (press to complete the selection and erase the objects)

Creating selection sets by picking objects can become quite tedious if you want to select a large number of objects. Just imagine having to pick a hundred or more objects in a large drawing! Fortunately AutoCAD provides a number of selection options which can help you select objects more efficiently.

Selecting Objects by Picking

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Introduction

Before you start to use the AutoCAD Modify commands, you need to know something about selecting objects. All of the Modify commands require that you make one or more object selections. AutoCAD has a whole range of tools which are designed to help you select just the objects you need. This tutorial is designed to demonstrate the use of many of the selection options. As with so many aspects of AutoCAD, developing a good working knowledge of these options can drastically improve your drawing speed and efficiency.

Perhaps the most obvious way to select an object in AutoCAD is simply to pick it. Those of you who have used other graphics based utilities will be familiar with this concept. Generally all you have to do is place your cursor over an object, click the mouse button and the object will be selected. In this respect AutoCAD is no different from any other graphics utility.

When you start a Modify command such as ERASE, two things happen. First, the cursor changes from the usual crosshairs to the pickbox and second, you will the the "Select objects" prompt on the command line. Both of these cues are to let you know that AutoCAD is expecting you to select one or more objects.

Select objects:

To select an object, place the pickbox over a part of the object and left-click the mouse. When the object has been picked it is highlighted in a dashed line to show that it is part of the current selection and the command line reports "1 found". You will now see the "Select objects" prompt on the command line again. At this point you can continue adding more objects to the current selection by picking them or you can press or the Space Bar to complete the selection.


The Crosshairs	The Pickbox	Highlighted Object

When you pick one or more objects in response to the "Select objects" prompt, you are effectively creating a selection set. Selection sets are an important concept in AutoCAD because they can be used to great effect, especially when drawings become large or complicated.

Modifying the Brightness

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Go once again to the Materials dialogue box, ViewRenderMaterials… from the pull-down menu. Select the material from the list on the left and click the Modify… button at the top of the right hand column. You now see the Modify Standard Material dialogue box, shown below.

The brightness and the strength or contrast of the material can be adjusted using a combination of two parameters, "Bitmap Blend" and "Value". The way a bitmap material looks is a combination of two components, the bitmap itself and the colour of the object to which it is attached. The Bitmap Blend parameter determines how much of the bitmap or object colour are seen. By default, when you create a new material, AutoCAD sets the Bitmap Blend value to 1.00. This means that only the bitmap is seen and none of the object colour. Setting this value to 0.00 means that only the object colour is seen and none of the bitmap. Between these two values, varying proportions of both bitmap and object colour are seen. The Value parameter controls the brightness of the object colour. The default value of 0.70 gives the true object colour. A lower value causes the colour to darken and a higher value causes the colour to brighten. The Value parameter has absolutely no effect on the material when Bitmap Blend is set to 1.00 because none of the object colour can be seen. However, by adjusting the two values together, it is possible to get just the effect you want.

The settings shown in the illustration above result in the rendered image on the right. Again, this is another of those situations where you really need to play about with the parameters to get a feeling for them and to finish up with just the result you are looking for.

You can use the Preview to get a crude idea of how the changing values affect the material but you will need to render the model to see the results properly. So, when the preview looks about right, click the OK button to return to the Materials dialogue box, OK again to return to the command prompt and then do a final render.

Bitmap Blend = 0.0

Bitmap Blend = 0.5

Bitmap Blend = 1.0

More on Bitmap Blend

Bitmap Blend and the object colour can be used in combination to vary the way the rendered material appears. For example, the 3 cubes on the left have object colours of magenta, red and blue. Each cube also has the Grass material attached. The cubes on the top row have Bitmap Blend set to 0.0, so none of the bitmap is seen. The cubes in the middle row have a Bitmap Blend value of 0.5, so we see 50% of the object colour and 50% of the bitmap. The cubes on the bottom row have a Bitmap Blend value of 1.0, in this case, we see none of the object colour.

The four cubes below all have an object colour of blue. Each cube has the Grass material attached and the Bitmap Blend variable has been set (from left to right) to 0.2, 0.4, 0.6 and 0.8 respectively. You can clearly see the change from object colour to bitmap.

Bear in mind that once Bitmap Blend has been set to a value of less than 1.0, you can also use the Value variable to change the brightness of the object colour. Used in combination, these parameters give amazing control over the way a material looks when it is rendered. As usual, in order to achieve a good understanding of how these parameters affect the final result, you need to experiment.

Modifying the Material

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AutoCAD enables you to modify materials in many ways. There are lots of parameters that can be used to change the way a material looks. In this particular case, we'll look only at methods for modifying the scale and the brightness.

Modifying Scale

If we want the grass stripes to appear twice as wide as they are shown, we'll need to scale up the bitmap by a factor of two. We could go back to Photoshop and double the size of the image but that wouldn't be particularly efficient. Instead, we'll work with AutoCAD. Go to the Materials dialogue box, ViewRenderMaterials… from the pull-down menu. Select the material from the list on the left and click the Modify… button at the top of the right hand column. Then, click on the button that says "Adjust Bitmap…". The next thing you see will be the Adjust Material Bitmap Placement dialogue box, shown below.

You can use the settings in this dialogue to change many aspect of the bitmap geometry. However, all we want to do is double the scale at which the bitmap is displayed. First, check the Maintain Aspect Ratio option at the bottom left of the dialogue box. Then, enter the value 2 in either the U or V scale edit boxes. Since the default scale is 1, setting the value to 2 will double it. Click the OK button to return to the Modify Standard Material dialogue box, OK again to return to the Materials dialogue and OK a third time to return to the AutoCAD Command prompt. Now render the model again to see the result of your modification. You can see from the illustration on the right that the scale is now correct but the material is still too bright.

Rendering the Model

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Now that you have created and attached the new material to part of your model, you will want to render the model to see what the new material looks like. Bear in mind that the material will look different in different lighting conditions, so make sure that you have set up any lights you might need before you render the model. See the Adding Sunlight to your Drawings tutorial for details on how to set up a light that simulates sunlight.

To render the model, select ViewRenderRender… from the pull-down menu. You will now see the Render dialogue box, shown above. Set the Render Type to either "Photo Real" or "Photo Raytrace". Materials will not be displayed if the default "Render" render type is used. Also, make sure that the Apply Materials option is checked in the Rendering Options section of the dialogue box. Click the Render button to begin the render.

The first render with the new material is shown in the illustration on the right. As you can see, there are two problems with it. First of all, the stripes are too narrow, they should be about twice the width. Second, the rendered effect in the prevailing lighting conditions is far too bright. In order to get the material to display the way we want, we're going to have to make some modifications.

Attaching the Material by Layer

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Materials can be attached to objects by selecting them or they can be attached by association with the object's colour or layer. In most cases, if your drawing is correctly layered, attaching materials by layer is the most sensible option. In the case of the example used here, the ground plane is on a layer called "GROUND". Since the new material is called MOWN GRASS, all we need to do is attach the MOWN GRASS material to the GROUND layer.

Go to the Materials dialogue box if you don't already have it open and click the By Layer… button at the bottom of the right hand column. The next thing you will see is the Attach by Layer dialogue box, shown below.

Simply select the material you want to attach from the list on the left, select the layer you want to attach it to from the list on the right and then click the Attach-> button. When you have done this, the material name will appear adjacent to the layer name in the list on the right. Click the OK button to complete the process and return to the Materials dialogue box. Finally, click the OK button in the Materials dialogue box to return to the Command prompt.

Creating the Material

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Start AutoCAD and open the drawing you want to render. Go to the Materials dialogue box, ViewRenderMaterials… from the pull-down menu. In the right hand column, you will see a drop-down list with a "New…" button above it. Select "Standard" from the list if it is not already selected and then click the New… button. You will now see the New Standard Material dialogue box, illustrated below.

Creating the material is very simple.

Give the material a suitable name.
Click the Find File… button and select the image you just created in Photoshop. Remember to set the file type in the Bitmap File dialogue.
Finally, click the Preview button to check that all is well. That's it! Click the OK button to return to the Materials dialogue box.

The next step is to attach the new material to an object and render it to see what it looks like.

Creating the Bitmap Tile

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Before we get to grips with AutoCAD materials, we need to create an image that will be used as the basis of the AutoCAD material. In this tutorial, we will use Photoshop for this part of the process but you can use another bitmap editor if you prefer.

Start Photoshop and open a new image, FileNew… from the pull-down menu. You will now see the New image dialogue box. You can use this dialogue box to give your image a Name and to set the Width and Height dimensions. OK, so how big should the bitmap tile be? Well, it depends on how complex your material is. In this case and in most cases where the pattern is relatively simple, a tile of 100 pixels by 100 pixels will work just fine. So, give the image a suitable name, set the measurement units to pixels (if they aren't already) and enter a value of 100 for both the Width and the Height. Click the OK button.
Next, use the Rectangular Marquee Tool to select one half of the image. You can do this with precision by looking at the Info Palette as you drag the marquee.
Now use the Color palette to select a green for the grass and then use the Paint Bucket Tool to flood fill the half of the bitmap which is selected. Your image should now look something like the illustration on the right.
Select the other half of the image by inverting the selection, SelectInverse from the pull-down menu. Select a complimentary green from the Color palette for the other half of the image and use the Paint Bucket Tool to fill the selection. Your image should now look similar to the one on the right. So far, we've just used flat colours to create our bitmap but grass has a texture to it that our image doesn't have. In order to make our grass look a little more realistic, we'll add some texture to the image.

The Photoshop Noise filter is probably one of the most useful filters that comes with the application. Most materials look better with a bit of texture, whether you are creating grass, concrete, rock or whatever. In all cases, the Noise filter can be used to add just the right amount of texture.

Start the Noise filter from the pull-down menu, FilterNoiseAdd Noise…. You will be presented with a small dialogue box that enables you to control the amount and type of noise you want to add to the image.
As you can see from the illustration on the right, there are three basic controls. The first, Amount, is fairly obvious, use the slider to set the percentage of noise. The Distribution option changes the pattern of noise; Gaussian looks slightly more random than Uniform. Finally, the Monochromatic option can be used to determine the colour of the noise. Basic noise adds a range of colours to the image, irrespective of the colour of the background. When Monochromatic is selected, the colour of the added noise matches that of the background. The best way to get to grips with these controls is to play about with them. For the grass image, the settings shown in the illustration were used.
When you are happy with the image, you will need to save it so that it can be used by AutoCAD. What format should be used and where should it be saved? Well, AutoCAD can use a number of common bitmap file formats and so the sensible option is to keep the file size as small as possible, so JPEG is a good format to use.

If you intend to keep this material for future use, it is a good idea to save the image somewhere sensible (not the Desktop!) like the folder where you keep your textures or to the AutoCAD texture folder, usually C:/Program Files/AutoCAD/Textures. This is important because every time you render using the new material, AutoCAD must find the image file in order to render the material correctly. If the image file is moved or deleted, AutoCAD will not find it and your rendered image will not look right.

To save the image, use the Photoshop Save for Web option, FileSave for Web… from the pull-down menu. This will allow you to choose a suitable compression level.

Tips & Tricks

2008-06-01T15:09:00.000-07:00

You will have noticed that many of the draw commands require the key on the keyboard to be pressed to end them. In AutoCAD, clicking the right mouse key and selecting "Enter" from the context menu has the same effect as using the key on the keyboard. Using the right-click context menu is a much more efficient way of working than using the keyboard.
You can also use the key or right mouse click to repeat the last command used. When a command has ended, you can start it again by right clicking and selecting "Repeat command" from the context menu rather that entering the command at the keyboard or selecting it from the pull-down or toolbar. By this method it is possible, for example, to repeat the line command without specifically invoking it. The command sequence might be something like the one below.

Command Sequence

Command: LINE
Specify first point: (pick P1)
Specify next point or [Undo]: (pick P2)
Specify next point or [Undo]: (right-click and select Enter)
Command: (right-click and select Repeat Line)
Specify first point: (pick P1)
Specify next point or [Undo]: (pick P2)
Specify next point or [Undo]: (right-click and select Enter)
Command: (right-click and select Repeat Line)…

You could continue this cycle as long as you needed, using only the mouse for input.

You can change the Linetype of any of the objects created in the above tutorial. By default all lines are drawn with a linetype called "Continuous". This displays as a solid line. However, lines can be displayed with a dash, dash-dot and a whole range of variations. See the Object Properties tutorial for details.

The Multiline Style Command

2008-06-01T15:07:00.000-07:00

Toolbar	none
Pull-down	FormatMultiline Style…
Keyboard	MLSTYLE

The Multiline style command is used to create new multiline styles, which can then be used with the Multiline command. When you start the command for the first time, you will see the Multiline Styles dialogue box indicating that the Standard style is "Current". To create a new style, enter a new style name in the "Name" edit box by overwriting "STANDARD" and enter an optional description in the "Description" edit box. The dialogue box should now look something like the one on the right. When you are happy with the new name and description, simply click on the "Add" button. Your new style will now appear in the "Current" box. The new style you have created is simply a copy of the Standard style, so the next step is to change the style to suit your own purposes. Click on the "Element Properties…" button to proceed.

You will now see the Element Properties dialogue box appear. This dialogue box allows you to add new line elements or delete existing ones and to control the element offset, colour and linetype. Click the "Add" button to add a new element. A new line element now appears with an offset of 0.0, in other words, this is a centre line. Highlight the top element in the "Elements" list and change the offset to 1.0 by entering this value in the "Offset" edit box. Now do the same with the bottom element remembering to enter a value of -1.0 because this is a negative offset. You now have a multiline that is 2 drawing units wide with a centre line. Let's now change the colour and linetype of the centre line.

Highlight the 0.0 offset element by clicking it in the "Elements" list. To change the colour, simply click on the Colour… button and select an appropriate colour from the palette. When a colour has been selected, click the "OK" button on the palette to return to the Element Properties dialogue box.

Changing the linetype is a little more complicated because we will need to load the required linetype first. However, click on the "Linetype…" button to proceed.

The Select Linetype dialogue box appears with just a few solid linetypes listed, ByLayer, ByBlock and Continuous. Click on the "Load…" button. The Load or Reload Linetypes dialogue box now appears. Scroll down the list of linetypes until you find one called "Hidden". Highlight Hidden and then click the "OK" button. You will now see the Hidden linetype appear in the "Loaded linetypes" list in the Select Linetype dialogue box, which should now look similar to the one shown above. Finally, highlight Hidden and click the "OK" button. Your Element Properties dialogue box should now look similar to the one in the illustration above. To complete our new style, we will add some end caps and a solid fill. Click on the "Multiline Properties…" button to proceed.

In the Multiline Properties dialogue box, click in the "Line" check boxes under "Start" and "End". This will have the effect of capping the ends of the multiline with a 90 degree line. As you can see from the dialogue box, you can change this angle if you wish to give a chamfered end. Next, click the "On" check box in the "Fill" section and then click on the Colour… button and select the fill colour from the palette. The Multiline Properties dialogue box should now look like the one in the illustration on the left. Finally, click the "OK" button in the Multiline Properties dialogue box and again in the Multiline Style dialogue box. You are now ready to draw with your new multiline.

Start the Multiline command, pick a number of points and admire your handiwork. If you have followed this tutorial closely, your new multiline should look something like the one in the illustration on the right. Notice the effect of the various changes you have made compared with the Standard multiline style.

One limitation of multiline styles is that you cannot modify a style if there are multilines referencing the style in the current drawing. This is a shame because it means that it is not possible to update multiline styles in the same way as it is possible to update text or dimension styles. You also cannot change the style of an existing multiline. If you really want to modify a multiline style, you will have to erase all multilines that reference the style first.

If you are new to AutoCAD, the whole process of working with multilines and creating multiline styles may appear a little bewildering because it touches upon a number of aspects of the program with which you may not be familiar. If this is the case, it may be a good idea to return to this tutorial in the future. Multilines are useful because they can save lots of time but their use is fairly specific and you should think carefully before using them. It may, for example, be more convenient simply to draw a polyline and to create offsets using the Offset command.

The Multiline Command

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Toolbar	custom
Pull-down	DrawMultiline
Keyboard	MLINE	short-cut	ML

The Multiline command is used to draw multilines. This process of drawing is pretty much the same as drawing polylines, additional line segments are added to the multiline as points are picked. As with polylines, points can be unpicked with the Undo option and multilines can be closed.

When you start the Multiline command you also have the option to specify the Justification, Scale and Style of the multiline. The Justification option allows you to set the justification to "Top", the default, "Zero" or "Bottom". When justification is set to top, the top of the multiline is drawn through the pick points, as in the illustration below. Zero justification draws the centreline of the multiline through the pick points and Bottom draws the bottom line through the pick points. Justification allows you to control how the multiline is drawn relative to your setting out information. For example, if you are drawing a new road with reference to its centre line, then Zero justification would be appropriate.

The Scale option allows you to set a scale factor, which effectively changes the width of the multiline. The default scale factor is set to 1.0 so to half the width of the multiline, a value of 0.5 would be entered. A value of 2.0 would double the width.

The Style option enables you to set the current multiline style. The default style is called "Standard". This is the only style available unless you have previously created a new style with the Multiline Style command. Follow the command sequence below to see how the Multiline command works and then try changing the Justification and Scale options.

Command Sequence

Command: MLINE
Current settings: Justification = Top, Scale = 20.00, Style = STANDARD
Specify start point or [Justification/Scale/STyle]: (Pick P1)
Specify next point: (Pick P2)
Specify next point or [Undo]: (Pick P3)
Specify next point or [Close/Undo]: (to end or continue picking or C to close)

The Point Style Command

2008-06-01T15:06:00.001-07:00

Toolbar	none
Pull-down	FormatPoint Style…
Keyboard	DDPTYPE

You can start the point style command from the keyboard by typing DDPTYPE or you can start it from the pull-down menu at FormatPoint Style… The command starts by displaying a dialogue box offering a number of options.

To change the point style, just pick the picture of the style you want and then click the "OK" button. You will need to use the Regen command, REGEN at the keyboard or ViewRegen from the pull-down to force any existing points in your drawing to display in the new style. Any new points created after the style has been set will automatically display in the new style.

One interesting aspect of points is that their size can be set to an absolute value or relative to the screen size, expressed as a percentage. The default is for points to display relative to the screen size, which is very useful because it means that points will remain the same size, irrespective of zoom factor. This is particularly convenient when drawings become complex and the drawing process requires a lot of zooming in and out.

The Point Command

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Toolbar	Draw
Pull-down	DrawPointSingle Point
Keyboard	POINT	short-cut	PO

The point command will insert a point marker in your drawing at a position which you pick in the drawing window or at any co-ordinate location which you enter at the keyboard. The default point style is a simple dot, which is often difficult to see but you can change the point style to something more easily visible or elaborate using the point style dialogue box. Points can be used for "setting out" a drawing in addition to construction lines. You can Snap to points using the Node object snap. See the Object Snap tutorial for details.

Command Sequence

Command: POINT
Current point modes: PDMODE=0 PDSIZE=0.0000
Specify a point: (pick any point)

Strangely, in Multiple Point mode (the default for the Point button on the Draw toolbar) you will need to use the escape key (Esc) on your keyboard to end the command. The usual right-click or enter doesn't work.

The Wipeout Command

2008-06-01T15:03:00.000-07:00

Toolbar	custom
Pull-down	DrawWipeout
Keyboard	WIPEOUT

A Wipeout is an image type object. Most commonly it is used to "mask" part of a drawing for clarity. For example, you may want to add text to a complicated part of a drawing. A Wipeout could be used to mask an area behind some text so that the text can easily be read, as in the example shown on the right.

The Wipeout command can be used for 3 different operations. It can be used to draw a wipeout object, as you might expect, but it can also be used to convert an existing closed polyline into a wipeout and it can be used to control the visibility of wipeout frames.

Command Sequence

Command: WIPEOUT
Specify first point or [Frames/Polyline] : (Pick P1)
Specify next point: (Pick P2)
Specify next point or [Undo]: (Pick P3)
Specify next point or [Close/Undo]: (Pick P4)
Specify next point or [Close/Undo]:

You can use as many points as you wish in order to create the shape you need. When you have picked the last point, use right-click and Enter (or hit the Enter key on the keyboard) to complete the command and create the wipeout.

You may find that it is easier to draw a polyline first and then convert that polyline into a wipeout. To do this, start the Wipeout command and then Enter to select the default "Polyline" option. Select the polyline when prompted to do so. Remember, polylines must be closed before they can be converted to wipeouts.

In most cases, you will probably want to turn off the wipeout frame.

Command Sequence

Specify first point or [Frames/Polyline] : F (the Frames option)
Enter mode [ON/OFF] : OFF
Regenerating model.

The Frames option is used to turn frames off (or on) for all wipeouts in the current drawing. You cannot control the visibility of wipeout frames individually. You should also be aware that when frames are turned off, wipeouts cannot be selected. If you need to move or modify a wipeout, you need to have frames turned on.

It is often more convenient to draw the wipeout after the text so that you can see how much space you need. In such a case, you may need to use the DRAWORDER command (ToolsDisplay OrderOption) to force the text to appear above the wipeout.

Tip: If you have the Express Tools loaded, you can use the very useful TEXTMASK command, which automatically creates a wipeout below any selected text. Find it on your pull-down at ExpressTextText Mask

The Region Command

2008-06-01T15:02:00.002-07:00

Toolbar	Draw
Pull-down	DrawRegion
Keyboard	REGION	short-cut	REG

A region is a surface created from objects that form a closed shape, known as a loop. The Region command is used to transform objects into regions rather than actually drawing them (i.e. you will need to draw the closed shape or loop first). Once a region is created, there may be little visual difference to the drawing. However, if you set the shade mode to "Flat Shaded", ViewShadeFlat Shaded, you will see that the region is, in fact, a surface and not simply an outline. Regions are particularly useful in 3D modeling because they can be extruded.

Before starting the Region command, draw a closed shape such as a rectangle, circle or any closed polyline or spline.

Command Sequence

Command: REGION
Select objects: (Pick P1)
Select objects:
1 loop extracted.
1 Region created.

You can use the boolean commands, Union, Subtract and Intersect to create complex regions.

The Ellipse Arc Command

2008-06-01T15:02:00.001-07:00

Toolbar	Draw
Pull-down	DrawEllipseArc
Keyboard	ELLIPSE A	short-cut	EL A

The Ellipse Arc command is very similar to the Ellipse command, described above. The only difference is that, in addition to specifying the two axis end points and the "distance to other axis" point, you are prompted for a start and end angle for the arc. You may specify angles by picking points or by entering values at the command prompt. Remember that angles are measured in an anti-clockwise direction, starting at the 3 o'clock position.

In truth, the Ellipse Arc command is not a new or separate command; it is just an option of the Ellipse command and it therefore has no unique command line name. It is curious why Autodesk considered this option important enough to give it it's own button on the Draw toolbar. Still, there it is.

Command Sequence

Command: ELLIPSE
Specify axis endpoint of ellipse or [Arc/Center]: A
Specify axis endpoint of elliptical arc or [Center]: (pick P1)
Specify other endpoint of axis: (pick P2)
Specify distance to other axis or [Rotation]: (pick P3)
Specify start angle or [Parameter]: 270
Specify end angle or [Parameter/Included angle]: 90

The Ellipse Command

2008-06-01T15:01:00.001-07:00

Toolbar	Draw
Pull-down	DrawEllipseAxis, End
Keyboard	ELLIPSE	short-cut	EL

The Ellipse command gives you a number of different creation options. The default option is to pick the two end points of an axis and then a third point to define the eccentricity of the ellipse. After you have mastered the default option, try out the others.

Command Sequence

Command: ELLIPSE
Specify axis endpoint of ellipse or [Arc/Center]: (pick P1)
Specify other endpoint of axis: (pick P2)
Specify distance to other axis or [Rotation]: (pick P3)

The ellipse command can also be used to draw isometric circles. See the worked example in the Drawing Aids tutorial to find out how to do this and how to draw in isometric projection with AutoCAD.

The Spline Command

2008-06-01T15:00:00.001-07:00

Toolbar	Draw
Pull-down	DrawSpline
Keyboard	SPLINE	short-cut	SPL

The Spline command creates a type of spline known as a nonuniform rational B-spline, NURBS for short. A spline is a smooth curve that is fitted along a number of control points. The Fit Tolerance option can be used to control how closely the spline conforms to the control points. A low tolerance value causes the spline to form close to the control points. A tolerance of 0 (zero) forces the spline to pass through the control points. The illustration on the right shows the effect of different tolerance values on a spline that is defined using the same four control points, P1, P2, P3 and P4.

Splines can be edited after they have been created using the SPLINEDIT command, ModifyObjectSpline from the pull-down menu. Using this command, you can change the tolerance, add more control points move control points and close splines, amongst other things. However, if you just want to move spline control points, it is best to use grips. See the Stretching with Grips section of the Modifying Objects tutorial for details.

Command Sequence

Command: SPLINE
Specify first point or [Object]: (Pick P1)
Specify next point: (Pick P2)
Specify next point or [Close/Fit tolerance] : (Pick P3)
Specify next point or [Close/Fit tolerance] : (Pick P4)
Specify next point or [Close/Fit tolerance] :
Specify start tangent: (pick a point)
Specify end tangent: (pick a point)

You can create linear approximations to splines by smoothing polylines with the PEDIT command, from the pull-down menu. However, you can also turn polylines into true splines using the Object option of the Spline command

The Arc Command

2008-06-01T14:59:00.001-07:00

Toolbar	Draw
Pull-down	DrawArc3 Points
Keyboard	ARC	short-cut	A

The Arc command allows you to draw an arc of a circle. There are numerous ways to define an arc, the default method uses three pick points, a start point, a second point and an end point. Using this method, the drawn arc will start at the first pick point, pass through the second point and end at the third point. Once you have mastered the default method try some of the others. You may, for example need to draw an arc with a specific radius. All of the Arc command options are available from the pull-down menu.

Command Sequence

Command: ARC
Specify start point of arc or [Center]: (pick P1)
Specify second point of arc or [Center/End]: (pick P2)
Specify end point of arc: (pick P3)

It is also possible to create an arc by trimming a circle object. In practice, many arcs are actually created this way. See the Trim command on the Modifying Objects tutorial for details.

The Circle Command

2008-06-01T14:58:00.000-07:00

Toolbar	Draw
Pull-down	DrawCircleCenter, Radius
Keyboard	CIRCLE	short-cut	C

The Circle command is used to draw circles. There are a number of ways you can define the circle. The default method is to pick the centre point and then to either pick a second point on the circumference of the circle or enter the circle radius at the keyboard.

Command Sequence

Command: CIRCLE
Specify center point for circle or [3P/2P/Ttr (tan tan radius)]: (pick P1)
Specify radius of circle or [Diameter] <50.0195>: (pick P2 or enter the exact radius)

As you can see from the command prompt above the default options are always indicated in triangular brackets like so and command options appear within square brackets like so [Option]. Each option is separated by a forward slash like this /. You can choose to use the alternative options by typing them at the prompt. For example, the circle command gives you three extra options to define a circle. 3P which uses any three points on the circumference, 2P which uses two points on the circumference to form a diameter and Ttr which stands for Tangent Tangent Radius. Obviously to use this last option you need to have drawn two lines which you can use as tangents to the circle. Try these options out to see how they work. Note that to invoke a command option, you need only type the upper-case part of the option name. For example, if you want to use the Ttr option, you need only enter "T". There are two more circle options on the pull-down menu that enable you to draw a circle by defining the center and diameter or by using 3 tangents.

The 3D Polyline Command

2008-06-01T14:56:00.000-07:00

Toolbar	custom
Pull-down	Draw3D Polyline
Keyboard	3DPOLY

The 3D Polyline command works in exactly the same way as the Polyline command. The main difference between a normal polyline and a 3D polyline is that each vertex (pick point) of a 3D polyline can have a different value for Z (height). In normal (2D) polylines, all vertexes must have the same Z value.

3D polyline objects are not as complex as their 2D cousins. For example, they cannot contain arc segments and they cannot be given widths. However, they can be very useful for 3D modeling.

Command Sequence

Command: 3DPOLY
Specify start point of polyline: (pick a point)
Specify endpoint of line or [Undo]: (pick another point)
Specify endpoint of line or [Undo]: (pick a third point)
Specify endpoint of line or [Close/Undo]: (to end, C to close or continue picking points)

Notice that you are not prompted for a Z value each time you pick a point. You must either use one of the Object Snaps to pick a point with the required Z value or use the ".XY" filter to force AutoCAD to prompt for a Z value.

The Revcloud Command

2008-06-01T14:50:00.000-07:00

Toolbar	Draw
Pull-down	DrawRevision Cloud
Keyboard	REVCLOUD

The Revcloud command is used to draw a "freehand" revision cloud or to convert any closed shape into a revision cloud.

Command Sequence

Command: REVCLOUD
Minimum arc length: 66.6377 Maximum arc length: 116.6159
Specify start point or [Arc length/Object] (Pick P1)
Guide crosshairs along cloud path...
Move the mouse to form a closed shape; the command automatically ends when a closed shape is formed.
Revision cloud finished.

You can use the "Arc length" option to control the scale of the revision cloud. This is achieved by specifying the minimum and maximum arc length. The "Object" option is used to transform any closed shape, such as a polyline, spline or circle into a revision cloud.

The Polygon Command

2008-06-01T14:49:00.000-07:00

Toolbar	Draw
Pull-down	DrawPolygon
Keyboard	POLYGON	short-cut	POL

The Polygon command can be used to draw any regular polygon from 3 sides up to 1024 sides. This command requires four inputs from the user, the number of sides, a pick point for the centre of the polygon, whether you want the polygon inscribed or circumscribed and then a pick point which determines both the radius of this imaginary circle and the orientation of the polygon. The polygon command creates a closed polyline in the shape of the required polygon.

This command also allows you to define the polygon by entering the length of a side using the Edge option. You can also control the size of the polygon by entering an exact radius for the circle. Follow the command sequence below to see how this command works.

Command Sequence

Command: POLYGON
Enter number of sides <4>: 5
Specify center of polygon or [Edge]: (pick P1 or type E to define by edge length)
Enter an option [Inscribed in circle/Circumscribed about circle] (to accept the inscribed default or type C for circumscribed)
Specify radius of circle: (pick P2 or enter exact radius)

In the illustration above, the polygon on the left is inscribed (inside the circle with the polygon vertexes touching it), the one in the middle is circumscribed (outside the circle with the polyline edges tangential to it) and the one on the right is defined by the length of an edge.

The Rectangle Command

2008-06-01T14:45:00.001-07:00

Toolbar	Draw
Pull-down	DrawRectangle
Keyboard	RECTANGLE	short-cuts	REC, RECTANG

The Rectangle command is used to draw a rectangle whose sides are vertical and horizontal. The position and size of the rectangle are defined by picking two diagonal corners. The rectangle isn't really an AutoCAD object at all. It is, in fact, just a closed polyline which is automatically drawn for you.

Command Sequence

Command: RECTANG

Specify first corner point or [Chamfer/Elevation/Fillet/Thickness/Width]: (pick P1)
Specify other corner point or [Dimensions]: (pick P2)

The Rectangle command also has a number of options. Width works in the same way as for the Polyline command. The Chamfer and Fillet options have the same effect as the Chamfer and Fillet commands, see the Modifying Objects tutorial for details. Elevation and Thickness are 3D options.

Notice that, instead of picking a second point to draw the rectangle, you have the option of entering dimensions. Say you wanted to draw a rectangle 20 drawing units long and 10 drawing units wide. The command sequence would look like this:

Command Sequence

Command: RECTANG
Specify first corner point or [Chamfer/Elevation/Fillet/Thickness/Width]: (pick a point)
Specify other corner point or [Dimensions]: D
Specify length for rectangles <0.0000>: 20
Specify width for rectangles <0.0000>: 10
Specify other corner point or [Dimensions]: (pick a point to fix the orientation)

This method provides a good alternative to using relative cartesian co-ordinates for determining length and width. See the Using Co-ordinates tutorial for more details.

The Polyline Command

2008-06-01T14:44:00.001-07:00

Toolbar	Draw
Pull-down	DrawPolyline
Keyboard	PLINE	short-cut	PL

The Polyline or Pline command is similar to the line command except that the resulting object may be composed of a number of segments which form a single object. In addition to the two ends a polyline is said to have vertices (singular vertex) where intermediate line segments join. In practice the Polyline command works in the same way as the Line command allowing you to pick as many points as you like. Again, just hit to end. As with the Line command, you also have the option to automatically close a polyline end to end. To do this, type C to use the close option instead of hitting . Follow the command sequence below to see how this works.

Command Sequence

Command: PLINE
Specify start point: (pick P1)
Current line-width is 0.0000 Specify next point or [Arc/Halfwidth/Length/Undo/Width]: (pick P2)
Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: (pick P3)
Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: (pick P4)
Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: (pick P5)
Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: (or C to close)

In the illustration on the right, the figure on the left was created by hitting the key after the fifth point was picked. The figure on the right demonstrates the effect of using the Close option.

It is worth while taking some time to familiarise yourself with the Polyline command as it is an extremely useful command to know. Try experimenting with options such as Arc and Width and see if you can create polylines like the ones in the illustration above. The Undo option is particularly useful. This allows you to unpick polyline vertices, one at a time so that you can easily correct mistakes.

Polylines can be edited after they are created to, for example, change their width. You can do this using the PEDIT command, ModifyObjectPolyline from the pull-down menu.

The Polyline Family

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Polylines differ from lines in that they are more complex objects. A single polyline can be composed of a number of straight-line or arc segments. Polylines can also be given line widths to make them appear solid. The illustration below shows a number of polylines to give you an idea of the flexibility of this type of line.

You may be wondering, if Polylines are so useful, why bother using ordinary lines at all? There are a number of answers to this question. The most frequently given answer is that because of their complexity, polylines use up more disk space than the equivalent line. As it is desirable to keep file sizes as small as possible, it is a good idea to use lines rather than polylines unless you have a particular requirement. You will also find, as you work with AutoCAD that lines and polylines are operationally different. Sometimes it is easier to work with polylines for certain tasks and at other times lines are best. You will quickly learn the pros and cons of these two sorts of line when you begin drawing with AutoCAD.

The Ray Command

2008-06-01T14:42:00.000-07:00

Toolbar	custom
Pull-down	DrawRay
Keyboard	RAY

The Ray command creates a line similar to a construction line except that it extends infinitely in only one direction from the first pick point. The direction of the Ray is determined by the position of the second pick point.

Command Sequence

Command: RAY
Specify start point: (pick the start point)
Specify through point: (pick a second point to determine direction)
Specify through point: (to end or pick another point)

The Construction Line Command

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Toolbar	Draw
Pull-down	DrawConstruction Line
Keyboard	XLINE	short-cut	XL

The Construction Line command creates a line of infinite length which passes through two picked points. Construction lines are very useful for creating construction frameworks or grids within which to design.

Construction lines are not normally used as objects in finished drawings, it is usual, therefore, to draw all your construction lines on a separate layer which will be turned off or frozen prior to printing. See the Object Properties tutorial to find out how to create new layers. Because of their nature, the Zoom Extents command option ignores construction lines.

Command Sequence

Command: XLINE
Specify a point or [Hor/Ver/Ang/Bisect/Offset]: (pick a point)
Specify through point: (pick a second point)
Specify through point: (to end or pick another point)

You may notice that there are a number of options with this command. For example, the "Hor" and "Ver" options can be used to draw construction lines that are truly horizontal or vertical. In both these cases, only a single pick point is required because the direction of the line is predetermined. To use a command option, simply enter the capitalised part of the option name at the command prompt. Follow the command sequence below to see how you would draw a construction line using the Horizontal option.

Command Sequence

Command: XLINE
Hor/Ver/Ang/Bisect/Offset/: H
Through point: (pick a point to position the line)
Through point: (to end or pick a point for another horizontal line)

The Line Command

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Toolbar	Draw
Pull-down	DrawLine
Keyboard	LINE	short-cut	L

With the Line command you can draw a simple line from one point to another. When you pick the first point and move the cross-hairs to the location of the second point you will see a rubber band line which shows you where the line will be drawn when the second point is picked. Line objects have two ends (the first point and the last point). You can continue picking points and AutoCAD will draw a straight line between each picked point and the previous point. Each line segment drawn is a separate object and can be moved or erased as required. To end this command, just hit the key on the keyboard.

Command Sequence

Command: LINE
Specify first point: (pick P1)
Specify next point or [Undo]: (pick P2)
Specify next point or [Undo]: (to end)

You can also draw lines by entering the co-ordinates of their end points at the command prompt rather than picking their position from the screen. This enables you to draw lines that are off screen, should you want to. (See Using Co-ordinates for more details). You can also draw lines using something called direct distance entry. See the Direct Distance Entry tutorial for details.

Introduction

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This tutorial is designed to show you how all of the AutoCAD Draw commands work. If you just need information quickly, use the QuickFind toolbar below to go straight to the command you want or select a topic from the contents list above. Not all of the Draw commands that appear on the Draw toolbar are covered in this tutorial. Blocks, Hatch and Text for example are all tutorial topics in their own right!

The Draw commands can be used to create new objects such as lines and circles. Most AutoCAD drawings are composed purely and simply from these basic components. A good understanding of the Draw commands is fundamental to the efficient use of AutoCAD.

The sections below cover the most frequently used Draw commands such as Line, Polyline and Circle as well as the more advanced commands like Multiline and Multiline Style. As a newcomer to AutoCAD, you may wish to skip the more advanced commands in order to properly master the basics. You can always return to this tutorial in the future when you are more confident.

In common with most AutoCAD commands, the Draw commands can be started in a number of ways. Command names or short-cuts can be entered at the keyboard, commands can be started from the Draw pull-down menu, shown on the right or from the Draw toolbar. The method you use is dependent upon the type of work you are doing and how experienced a user you are. Don't worry too much about this, just use whatever method feels easiest or most convenient at the time. Your drawing technique will improve over time and with experience so don't expect to be working very quickly at first.

If you are working with the pull-down menus, it is worth considering the visual syntax that is common to all pull-downs used in the Windows operating system. For example, a small arrow like so "" next to a menu item means that the item leads to a sub-menu that may contain other commands or command options. An ellipsis, "…" after a menu item means that the item displays a dialogue box. These little visual clues will help you to work more effectively with menus because they tell you what to expect and help to avoid surprises for the newcomer.