Usually when you insert a file into a drawing, the block name and file name are the same. Likewise, when you WBLOCK a block, you usually name the file with the name of the block. Be aware that when you use block substitution, you have a block in your drawing that is the same as a file of a different name. For example, if you have a block in your drawing called smalldesk and substitute a file called bigdesk, you now have a block called smalldesk that is actually the same as the file bigdesk. This can become confusing, so use block substitution with care.

Creating and Using Dynamic Blocks

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The chair contains a point parameter with a move action. As a result, you can move the chair independently of the rest of the block. If you stretch the desk, you might want to move the chair so that it remains centered in front of the desk, or you might simply want to move the chair further away from the desk.

Figure 18-14: This dynamic block contains components that enable you to stretch the desk’s length and move the chair.

If you open a dynamic block in a prior release of AutoCAD or in AutoCAD LT, you see the last current view of the block. You cannot use the dynamic features of the block, but you can edit it as a regular block. The block is assigned a name, such as U2.

To change the background color of the Block Editor, choose Tools Options and click the Display tab. Click the Colors button. From the Window Element drop-down list, choose Block Editor Background. Then choose a color from the Color drop-down list. Click Apply & Close, and then click OK.

Understanding the work flow of dynamic blocks

Because defining a dynamic block takes some time — although simpler dynamic blocks are not very time-consuming to set up — the most common use for dynamic blocks is to create a block library. Normally, you define your dynamic blocks and save them for future use in your drawings. In other words, unless you need to insert a new block many times in several variations in a drawing, you won’t create dynamic blocks for the current drawing on which you’re working.

A block library can have two configurations:

One block per drawing: You save each block in its own drawing. Use the BASE command to specify the origin of the drawing, which is usually on an object snap somewhere on the block. (I explain the BASE command in the “Saving blocks as files” section earlier in this chapter.) You use the INSERT command to insert the drawing, thereby inserting its block.

Many blocks per drawing: You put a number of (usually) related blocks in a drawing. To insert the block, you use the DesignCenter to locate the drawing and find the individual block that you want. (See the section “Using the DesignCenter” earlier in the chapter for information on inserting blocks with the DesignCenter.)

The first part of the process of creating dynamic blocks is to define the block. I explain the details in the next few sections, but here I provide an overview of the workflow:

1.In your block library drawing or in a new drawing, create the block.

2.Open the new Block Editor (the BEDIT command) and choose the block.

3.Add parameters and associated actions.

4.Save the block definition in the Block Editor.

5.Close the Block Editor.

6.If the drawing will contain just this block, use the BASE command to set the drawing origin where you want the insertion point to be, usually somewhere on the block.

7.Save the drawing.

You may want to follow this process for any number of blocks. When your blocks are defined, you do the following to insert your dynamic blocks.

1.In your current drawing, either use the INSERT command to insert the drawing containing the block, or use the DesignCenter to choose the block from within the drawing.

2.Select the block to see its special grips. These grips show you where you can modify the block.

3.Usually, you click and drag a grip. Some dynamic block parameters involve choosing a visibility or lookup option.

Defining a dynamic block

To define a dynamic block, first create the objects that you want for the block, or explode an existing block down to its component objects. Then choose Block Editor from the

Standard toolbar, or choose Tools Block Editor to start the BEDIT command. In the Edit Block Definition dialog box, choose <Current Drawing> and click OK.

You may see a message that asks whether you want to see how dynamic blocks are created. Click Yes to open the New Features Workshop, which contains an animated tutorial on dynamic blocks. (You can access the New Features Workshop at any time from the Help menu.) Otherwise, click No. The Block Editor opens, as shown in Figure 18-15. At the same time, the Block Authoring palette opens.

Before you start defining your block, you need to decide the types of variations that you want the block to have. You build flexibility into your blocks with a combination of parameters and actions. Table 18-2 lists the parameters, the actions that you can add to each parameter, and a description of the possible uses for those parameters and actions on the specified component of the dynamic block.

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Figure 18-15: The Block Editor is a special window for authoring dynamic blocks.

Table 18-2: Dynamic Block Parameters and Actions

Adding a parameter

To create a dynamic block, you start by adding a parameter. Click the parameter that you want from the Parameters tab of the Block Authoring palette. Each parameter prompts you for the information it needs. For example, the linear parameter responds with the Specify start point or [Name/Label/Chain/Description/Base/Palette/Value set]: prompt. When you specify the start point, you get a prompt for the endpoint. The flip parameter prompts you for a reflection line, which is like a mirror line.

The options for each parameter are fairly similar. Here’s how to use the options:

Name: You can change the name of the parameter. The name appears in the Properties palette when you select the parameter. However, you may find it confusing to change the name, because the name clearly denotes which parameter the block uses. On the other hand, if you have more than one of the same type of action, such as two stretch actions, renaming the actions to identify what they apply to can eliminate confusion. For example, you could have two Move actions, “Move table” and “Move chair.”

Label: The label appears in the Properties palette, but also next to the block when you have the Block Editor open. Change the label to suit your needs. For example, the linear parameter uses a label of “Distance.” You might want to change that to Length, Width, or even something more specific.

Chain: Sometimes, you might want one action to cause more than one change in a block. To do this, you can chain parameters. Then, activating one parameter’s actions causes a secondary parameter’s action to occur. The primary parameter must have an action whose selection set includes the secondary parameter in addition to any other objects it will act on. (If the action is a stretch action, the stretch frame also needs to include the secondary parameter.) Then set the secondary parameter’s chaining property to Yes.

Description: You can add a description to a parameter. This description displays in the Properties palette when you select the parameter in the Block Editor.

Base: Creates a base point parameter, which sets a base point for the block.

Palette: By default, displays parameter labels in the Properties palette when you select the block reference in a drawing. Change to No if you don’t want to display the labels.

Value set: You can constrain the available values for your block’s size, either as increments (for example, from 3 feet to 7 feet in 6-inch increments) or by providing a list (for example, only 36", 40", and 42"). This option prompts you to choose either the increment or the list method, and then prompts you for values.

When you are finished using the options or have specified the necessary coordinates (such as a start point and endpoint for a linear parameter), the Specify label location: prompt appears. Pick a point to place the label for the parameter.

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An exclamation point now appears next to the parameter. This exclamation point alerts you that you have not yet added an action to the parameter. Most parameters require

an action to function properly. Figure 18-16 shows a chair with a linear parameter.

Figure 18-17: Use the Actions tab of the Block Authoring palettes to associate an action with a parameter.

To add an action, choose an appropriate action for your parameter. At the Select parameter: prompt, select the parameter. Remember that you always apply an action to a parameter, rather than to an object. However, as part of the process, you specify a selection set for the action, which means selecting the object or objects.

The next prompts depend on the action that you choose and on the parameter to which you’re attaching the action. Table 18-3 explains some of the prompt options that you find for commonly used actions.

Table 18-3: Action Prompt Options

Continued

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The final step is to specify the location of the action’s label. At this point, you can also use one of two options:

Multiplier: Multiplies the parameter value by a factor that you specify. For example, you can multiply a stretch by a factor of .5. For example, if you want to keep a circle centered inside a rectangle that you’re moving or stretching, use a .5 multiplier so that the circle moves or stretches half of the distance of the rectangle, thereby remaining centered.

Offset: Changes the parameter angle by an amount that you specify. For example, you can increase an angle by 30 degrees.

Adding visibility parameters

Visibility parameters enable you to turn the visibility of a block component on and off when you insert it. You can define multiple named visibility states, thereby creating many variations of visibility or invisibility. You can use visibility parameters in two ways:

Make one component visible or invisible: You can choose to display or not display one component. For example, if you have a telephone on a desk, you can display or not display the telephone.

Switch among multiple components: You can include variations of a component, and cycle among them during insertion. For example, you can have three types of telephones (such as single-line, two-line, and multiple-line), all in the same location, with one on top of the other. When inserting the block, you can choose which telephone to display.

Visibility parameters are a very powerful way to add flexibility to a block and to reduce the number of similar blocks you store. You can add only one visibility parameter per block.

To add a visibility parameter, follow these steps:

1.Open the Block Editor in a drawing that contains the components that you need. If you want to switch among multiple components, place them on top of each other.

2.Choose Visibility Parameter from the Parameters tab of the Block Authoring palettes, and place it near the components.

3.Choose Manage Visibility States on the Block Editor toolbar (or double-click the visibility parameter) to open the Visibility States dialog box, shown in Figure 18-18.

Figure 18-18: Use the Manage Visibility States dialog box to add and name visibility states.

4.Click the default visibility state (VisibilityState0) to select it. Enter a new name for your first state and press Enter. The name should relate to what the state will display. In the telephone example, you might use telephone or single-line as the state.

5.Click New to open the New Visibility State dialog box, shown in Figure 18-19.

Figure 18-19: The New Visibility State dialog box.

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6.Enter a new visibility state name. In the telephone example, you might use no telephone or two-line. To leave the visibility of existing objects unchanged, use the default option, Leave Visibility of Existing Objects Unchanged in New State. If you want the new state to hide all objects, choose Hide All Existing Objects in New State. To display all objects, choose Show All Existing Objects in New State. Whichever option you choose, you can change the visibility of individual objects for each state afterwards. Click OK.

7.If you need more visibility states, repeat Step 5 and 6 until you’re done.

8.Click OK to close the Visibility States dialog box and return to the Block Editor.

9.Choose the first state from the Visibility States drop-down list at the right side of the Block Editor’s toolbar. For that state, select all of the objects that you want to

make invisible, if any. Then Click the Make Invisible button on the Block Editor’s toolbar.

10.Repeat Step 10 for each state. If you chose to hide objects when you created the state, you may instead need to make certain objects visible by clicking the Make Visible button.

11.Check each visibility state by choosing each state in turn from the Visibility States drop-down list and making sure that each state displays what you want it to display.

When you insert the dynamic block and select it, you see a down arrow. Click the arrow to display the list of visibility states. Choose the state that you want.

Adding lookup parameters and actions

A lookup parameter/action combination creates a table that pairs labels with values. For example, you might have a desk that comes in three sizes. You can create this desk and use the Value Set option to create a list of three sizes: 4 feet, 5 feet, and 6 feet. You can then create labels that say 4’ desk, 5’ desk, and 6’ desk. When you insert the desk, you can choose the label that you want from a drop-down list; the desk automatically stretches to the proper size. You don’t need to use the Value Set option, as you can specify values in the lookup table.

Lookup tables are great when you want pre-set sizes for a block. When you insert the block, you don’t even have to think about exact measurements; you just choose from a drop-down list, as shown in Figure 18-20.

Figure 18-20: You can specify a pre-set size by choosing from the drop-down list.

To create a lookup parameter and action, follow these steps:

1.In the Block Editor, add another parameter and action that you will use as the basis for the Lookup parameter and action. For example, add a linear parameter and a stretch action. If you add a value set (list or increment), the measurements will be available in advance when you create the lookup table.

2.From the Parameters tab of the Block Authoring palettes, add a lookup parameter.

3.From the Actions tab, add a lookup action. At the prompt, select the lookup parameter and place the lookup action. The Property Lookup Table dialog box opens.

4.Click the Add Properties button, choose the parameter that you want to work with (for example, the linear parameter), and click OK. You return to the Property Lookup Table dialog box, as shown in Figure 18-21.

Figure 18-21: The Property Lookup Table dialog box enables you to associate values with labels.

5.If you have values from a value set, you can see them by clicking the first row in the Input Properties side of the dialog box. A drop-down arrow appears. Choose the first value. If you don’t have a value set, you can enter values on each row. Click the same row on the Lookup Properties side of the dialog box and enter the label that corresponds with the value. For example, in Figure 18-21, the label was Desk Chair. Then click the next row, choose the next value, and enter the next label. Continue until you’re done.

6.Click the lower-right cell in the dialog box, which says Read Only by default. Choose Allow Reverse Lookup. (To do this, all of the rows in the table must be unique.) You need to use this option in order to choose a value from a drop-down list of labels when you insert the block.

7.Click OK to return to the Block Editor.

Now each value in the lookup table is associated with the labels that you entered.

Using parameter sets

The Parameter Sets tab of the Block Authoring palettes contains a number of ready-made parameter-action combinations that you can use. These sets are great for quick creation of dynamic blocks that are not complex. Hover the cursor over any parameter set to see a tooltip explaining the set’s functioning.

When you place a parameter set, you see that exclamation point, because you have not yet selected the objects for the action. Double-click the action to display prompts that allow you to select objects.

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Saving dynamic blocks and closing the Block Editor

When you have finished creating a dynamic block, click Save Block Definition on the Block Editor toolbar. Always save the block definition before closing the Block Editor.

Then click the Close Block Editor button.

If you want to put the base point for the block somewhere on the block, use the BASE command. Then save your drawing.

Inserting and modifying dynamic blocks

You insert a dynamic block in the same way that you insert a regular block: by using the Insert dialog box or the DesignCenter. For more information, see “Inserting Blocks and Files into Drawings” earlier in this chapter.

During insertion, you can press Ctrl to cycle among the grips if their Cycling property is set to Yes. Each time you press Ctrl, the cursor moves to another grip on the block.

To modify the block to use its dynamic features, first select the block. You see special, turquoise dynamic block grips, depending on the type of action. For example, in Figure 18-14, you see grips for stretch and move actions. You click and drag these grips in the same way that you do for regular grips; the difference is that the resulting modification is controlled by the parameters and actions that you defined. If you have created a value set, you see vertical lines at the available lengths, as shown in Figure 18-22. Lookup and visibility actions have a down arrow so that you can open a drop-down list and choose a visibility state or lookup label.

Figure 18-22: This block can be a chair, loveseat, or sofa.

The vertical lines indicate the available lengths as you drag.

STEPS: Creating and Inserting Dynamic Blocks

1.Open ab18-f.dwg from the CD-ROM. This is a set of office furniture, as shown in Figure 18-23.

2.Save the drawing as ab18-06.dwg in your AutoCAD Bible folder.

3.Hover the cursor over any part of the drawing. You can see that it is all one block, called DeskSet.

Figure 18-23: The office furniture is a block that can be more useful if they are dynamic.

4.Choose Block Editor from the Standard toolbar. In the Edit Block Definition dialog

box, choose DeskSet and click OK. The Block Editor opens with the desk set (including a desk, armchair, computer, monitor, and phone) displayed. Inside the Block Editor, you work with the individual components of the DeskSet block. The Block Authoring palette also opens.

5.You want to be able to move the armchair separately from the rest of the block. To add a point parameter to the chair, click the Parameters tab of the Block Authoring palettes and choose Point Parameter.

6.Follow these prompts:

Specify parameter location or [Name/Label/Chain/Description/Palette]:

Right-click and choose Label.

Enter position property label <Position>: Chair Location

Specify parameter location or [Name/Label/Chain/Description/Palette]:

Pick the endpoint at the middle of the front of the chair.

Specify label location: Pick a location for the Chair Location label.

7.To add a move action to the point parameter, click the Actions tab and choose Move Action. Follow the prompts:

Select parameter: Select the point parameter by clicking its label.

Specify selection set for action. Select objects: Select all of the objects that make up the chair. (In this instance, it doesn’t make any difference whether or not you include the actual parameter in the

selection set.)

Select objects:

Specify action location or [Multiplier/Offset]: Place the action in the middle of the chair (or anywhere near the chair).

8.To add a linear parameter to the desk, click the Parameters tab and choose Linear Parameter. Follow the prompts:

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Specify start point or [Name/Label/Chain/Description/Base/Palette/ Value set]: Right-click and choose Label.

Enter distance property label <Distance>: Desk length Specify start point or

[Name/Label/Chain/Description/Base/Palette/Value set]: Right-click and choose Value set.

Enter distance value set type [None/List/Increment] <None> : Choose Increment from the drop-down list.

Enter distance increment: 6 Enter minimum distance: 48 Enter maximum distance: 72 Specify start point or

[Name/Label/Chain/Description/Base/Palette/Value set]: Choose the endpoint at the upper-left corner of the desk.

Specify endpoint: Choose the endpoint at the upper-right corner of the desk.

Specify label location: Pick a location above the desk.

9.To simplify matters, we only want the right grip for the linear parameter. This makes sure that the desk can only be stretched towards the right. Select the linear parameter. Right-click and choose Grip Display 1. The left grip disappears.

10.Click the Actions tab and choose Stretch Action. Follow the prompts:

Select parameter: Select the linear parameter by clicking its label.

Specify parameter point to associate with action or enter [sTart point/Second point] <Start>: Pass the cursor over the right grip and click.

Specify first corner of stretch frame or [CPolygon]: Click at 1 in Figure 18-24.

Specify opposite corner: Click at 2.

Specify objects to stretch. Select objects: Click close to but not on top of 2.

Specify opposite corner: Click close to but not on top of 1.

Select objects:

Specify action location or [Multiplier/Offset]: Place the action label to the right of the grip on the right side of the desk.

11.The block should look like Figure 18-24.

12.To allow for various size monitors, click the Parameters tab and choose Linear Parameter. Right-click and choose the Label option. Type Monitor width .

13.At the next two prompts, pick points 3 and 4 in Figure 18-24. Then place the parameter label above the monitor.

14.You can also create a value set in the Properties palette. Select the Monitor width parameter and open the Properties palette (Ctrl+1). In the Value Set section, choose List from the Dist Type drop-down list. Next to the Dist Value List item, click the Ellipsis

(. . .) button to open the Add Distance Value dialog box. The current width is already there. In the Distances to Add text box, type 18-1/2 . The value changes to 1'-6 1⁄2" and moves below to the list box. Again in the Distances to Add text box, type 20-1/2 . Click OK to close the dialog box. Close or minimize the Properties palette.

15.Select the linear parameter. Right-click and choose Grip Display 1.

1

3 5 4 6

2

Figure 18-24: The DeskSet block after adding a move action to the armchair and a stretch action to the desk.

16.Click the Actions tab on the Block Authoring palette and choose Stretch Action. At the Select parameter: prompt, select the linear parameter that you just created. At the next prompt, click the right parameter point. To specify the stretch frame, pick 5 and then 6 in Figure 18-24. To select objects, pick near 6 and then near 5. Press Enter to end selection. Specify a label location above the monitor.

17.We want to create a lookup parameter for the monitor. On the Parameters tab, choose Lookup Parameter and pick a location on the monitor. On the Actions tab, choose Lookup Action. Select the lookup parameter and select a location just below it. The Property Lookup Table dialog box opens.

18.Click Add Properties. In the Add Parameter Properties dialog box, choose the Linear 1 parameter and click OK. Back in the Property Lookup Table dialog box, click the first row on the Input Properties side, below the Monitor width heading, and choose the first measurement from the drop-down list. In the same row on the Lookup Properties side, type 15 monitor. (Note that monitors are measured diagonally, and so the horizontal width of a 15" monitor is not 15".) In the second row on the Input Properties side, choose the second measurement and enter 17" monitor on the right. In the third row on the left, choose the last measurement and enter 19" monitor on the right.

19.Click the Read Only cell and choose Allow reverse lookup from the drop-down list. The Property Lookup Table dialog box should look like Figure 18-25. Click OK.

20.Because some people may not have a phone, we want to create a visibility parameter and action for the phone. On the Parameters tab, choose Visibility Parameter. Follow the prompts:

Specify parameter location or [Name/Label/Description/Palette]:

Right-click and choose Label.

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Enter visibility property label <Visibility>: Phone/No Phone Specify parameter location or [Name/Label/Description/Palette]: Pick a location near the phone.

Figure 18-25: The Property Lookup Table dialog box is ready to create a lookup table for the computer monitor.

21.Choose Manage Visibility States from the Block Editor toolbar. The Visibility States dialog box opens. Click the VisibilityState0 item and type Has phone . Click New.

In the Visibility State Name text box of the New Visibility State dialog box, type No phone. Click OK twice to return to the Block Editor.

22.From the Visibility States drop-down list, make sure that No Phone is displayed; if

not, choose it. Click the Make Invisible button on the Block Editor toolbar. At the Select objects: prompt, select all of the objects of the phone and press Enter to end selection. To double-check the visibility states, choose the Has Phone state and make sure that the phone appears.

23.Your block should look like Figure 18-26. Click Save Block Definition on the Block Editor toolbar. At the message asking whether you want to update the block refer-

ence in the drawing, click Yes. Then click Close Block Editor. Save your drawing.

24.Open a new drawing based on the default template or any template that you usually use. Open the DesignCenter. In the Folder List pane, browse to, and double-click, ab18-06.dwg. Click Blocks. Drag the DeskSet block from the right side of the DesignCenter to your drawing.

Note If you create a block inside a drawing and then make it dynamic, you need to use the DesignCenter to insert it. If you try to insert the entire drawing, you see only a regular block. However, if you don’t create a block in the source drawing and create the dynamic block in the Block Editor without ever creating and naming a block, you can use the INSERT command to insert the entire drawing and use the dynamic features of the block.

25.Choose Zoom Extents. Close or minimize the DesignCenter.

26.Select the DeskSet block. It should look like Figure 18-27.

Figure 18-26: The completed dynamic block in the Block Editor.

Move action

Figure 18-27: When you select a dynamic block, you see grips for its dynamic features.

27.Click the desk’s stretch grip and stretch the desk one vertical line to the left to make it 6 inches shorter. The computer moves with the desk.