About Constraints

The Interactive Drafting workbench lets you create geometrical constraints, which specify explicitly how the geometry should behave. A constraint applies to up to three elements.

This page provides information that will help you understand and create constraints.

What Is a Constraint?

A constraint is a kind of relationship that lets you specify explicitly how the geometry should behave. In other words, if you modify the geometry afterwards via the geometry itself, these relations will be taken into account.

In the Interactive Drafting workbench, you can create geometrical constraints. Geometrical constraints set a relationship that forces a limitation between one or more geometrical elements. The various geometrical constraints are the following:


  • Support lines and circles
  • Alignment
  • Parallelism
  • Perpendicularity
  • Tangency
  • Concentricity
  • Horizontality
  • Verticality
  • Fix
  • Middle point
  • Equidistant point
  • Symmetrical
Important:
  • In the Interactive Drafting workbench, dimensional constraints do not exist as such. It is by Creating Driving Dimensions that you can drive constrained geometry.
  • It is impossible to modify the definition of a geometrical element (via the Definition dialog box) in a view which contains inconsistent or over-constrained geometry. In such a case, you first need to solve the inconsistencies or remove the extra constraints, and you will then be able to modify the definition of the geometrical element.

What Does Creating Constraints Mean?

You can create constraints using the Tools and Visualization toolbars:


  • Via the existing Show Constraints command (from the Visualization toolbar).
  • Via Autodetection, if you activate the Create Detected Constraints command (from the Tools toolbar) to automatically create detected constraints.

You can also create constraints via SmartPick:


  • When you use SmartPick, you detect geometric constraints dynamically. But SmartPick can simply be used to automatically detect constraints without necessarily creating them. For information on creating constraints using SmartPick, see Creating Constraints via SmartPick in the SmartPick chapter.
Important: If you want constraints to be created, make sure the Show Constraints icon, and optionally the Create Detected Constraints icon, are active in the Tools toolbar, before you start creating constraints.