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of the palette to open the Filters pane. Click the funnel icon in the toolbar to create a new filter group, and then simply drag and drop parameters into the group. Figure 19-14 shows the two constraints added in Steps 5 and 6 (of the preceding step list) dragged into a new group filter.

Figure 19-14: Filter your parameters to keep them organized.

Dimensions or constraints — have it both ways!

After all that hard work adding dimensional constraints to your drawings, it would be a downright shame to have to go back and apply regular dimensions, wouldn’t it? Well, you don’t have to. You can make dimensional constraints look and behave like regular dimensions. You can go the other way, too, and make your regular dimensions act like dimensional constraints.

Dimensional constraints are available in two flavors:

Dynamic constraints: The default form. Dynamic constraints appear gray with a padlock icon next to them in the drawing area. You can make them appear and disappear by clicking Show All in the Dimensional panel. They don’t plot, and they resize as you zoom in and out of the drawing, so they’re always legible.

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Annotational constraints: This form is controlled as an object property, so you have to set it in the Properties palette. Annotational constraints do plot, don’t resize as you zoom in and out, and don’t disappear as you toggle the Show All button on and off. Annotational constraints conform to dimension style settings.

The dimension name format of annotational constraints can be set to Name, Value, or Name and Expression, just like dynamic constraints (refer to Figure 19-10 for another look at the Constraint Settings dialog box). If you’re going to plot your drawing with annotational constraints, remember to reset the format so it doesn’t show the dimension name or the expression.

Here’s how to turn dynamic dimensional constraints into annotational constraints.

1.Open a drawing that contains some geometry with dimensional constraints.

You can also start a new drawing, draw some simple geometry, and add a dimensional constraint to two.

2.Select a dynamic constraint, right-click, and choose Properties.

The Properties palette opens with the object properties of the selected dimensional constraint listed in table form.

3.Click in the Constraint Form field, and in the drop-down list, change Dynamic to Annotational (see Figure 19-15).

The dynamic constraint becomes annotational, and takes on the appearance of the current dimension style. If you change the dimension style in the Properties palette, the annotational constraint updates to the new dimension style format.

You can go the other way, too, from regular dimension objects to dimensional constraints.

4.Add a linear, radius, diameter, aligned, or angular dimension (that is, a regular dimension, not a dimensional parameter) to your drawing geometry.

Nearly every type of dimension object has a parametric analog; the exceptions are arc length, jogged radius, jogged linear, and ordinate dimensions.

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446 Part IV: Advancing with AutoCAD

Figure 19-15: Turning dynamic constraints into annotational ones.

5.Click Convert in the Dimensional panel, select one of the dimension types in Step 4, and press Enter.

The Dimensional Constraint text box displays as soon as you click an associative dimension, and the dimension becomes a dynamic constraint as soon as you press Enter.

The only clue that a dimension is an annotational constraint rather than a regular old associative dimension is the padlock icon that appears next to the dimension value. You can turn off the display of the padlock in the Constraint Settings dialog box, but we recommend that you leave it on. It

doesn’t plot anyway, and you might decide to delete the dimension without realizing that’s it’s controlling your object geometry.

Annotational dimensions can also be annotative so that they size themselves automatically to the drawing scale. We cover annotative dimensions in Chapter 14. Annotational and annotative dimensions are also associative, so you can have annotative annotational associative dimensions. Try saying that after a few drinks.

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In this chapter, we present the two varieties of parametric constraints separately, but you’ll get the most mileage from this feature when you incorporate both geometric and dimensional constraints with all those other precision techniques that we tell you about in Chapter 7. In fact, if you start a drawing by using Snap, Ortho, Osnap, and other precision techniques before you start adding dimensional and parametric constraints, you’ll be well on the way to creating a library of intelligent drawings that maintain your design intent.

Geometric and dimensional constraints can be equivalent. For example, a 90-degree angle dimensional constraint is equal to a perpendicular geometric constraint, and AutoCAD won’t let you apply both.

All the examples in this chapter involve a single drawing view. Geometric constraints actually apply “to infinity,” and so you can synchronize objects in one orthographic view with those in another. For example, coincident and collinear constraints can link objects in the front view with their equivalents in the top and right-side views, and liberal use of the Equal constraint means that you should never have to measure or dimension anything twice, you should only ever need minimal construction geometry, any changes in one view reflect through to the others, and your views always remain orthogonally aligned.

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448 Part IV: Advancing with AutoCAD

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