Breakline Dynamic Block -- Part 1

Last week, I posted about a dynamic block breakline that I'd created to mimic the behavior of the Express Tool.

This week, I'll go through the steps to create it, showing you a few dynamic block tips and tricks along the way.

Step 1 is to create your geometry. I just drew a polyline in the shape of my default breakline.

Step 2 is to create a parameter. A parameter is essentially a type of property -- you can have parameters that define lengths, angles, positions, etc. The first parameter I'm going to create is a linear parameter. It simply defines the distance between two points.

So "Distance1" is now the distance between the center of the breakline and one end. (Notice that I held the end of the parameter back from the end a little. This lets the breakline hang over the edge without having to measure it each time.)

The exclamation point means that the parameter's not done -- it needs an action. Actions control changes in parameters.

Double-clicking on the exclamation point brings up the actions to choose from. For a linear parameter, you can choose Array, Move, Scale, or Stretch. Today, I want Stretch.

Next, I have to pick the parameter point to associate with this action. In other words, should moving the right-hand arrow change the geometry, or should the left-hand arrow? Stretching from the center wouldn't make much sense, so we'll use the right-hand arrow.

Next, I'm asked for a stretch frame. I need to window around the objects and points I want to stretch -- in this case, the right end of the breakline.

Unlike with the regular stretch command, though, drawing the window doesn't mean you're done. In the Block Editor, you still need to select the objects to stretch. This is nice, because it gives you more control over the objects in your dynamic block.

Once I select the polyline, the Action appears next to the parameter. The exclamation point doesn't go away, though, because there's still a parameter grip that doesn't have an action.

If you're on an earlier version of AutoCAD LT, your action will look like this instead:

I don't actually want to use that other grip, so I'll select the parameter and use the Properties palette to set the number of grips to 1.

Testing the block shows me that my stretch action is working as intended. Tune in next time for options for stretching the other end of the breakline.

When this is done, I'll post a video showing the creation process start-to-finish.