KOMPAS-3D v24

The difference between a parametric and a regular image is that the parametric image stores information both on location and characteristics of geometrical objects and on constraints applied to them.

Under constraint refers to the dependency between parameters of a separate object or the equality of an object parameter to a constant. It is only permitted to edit a document so that the established relations are not broken.

Some examples of such constraints are verticality and horizontality of segments and straight lines. Verticality of a segment is identical to equality of X-coordinates of its ends or to its slope angle equality to 90°. A segment with such a constraint can be moved but cannot be rotated, i.e. its slope angle cannot be changed.

In addition, constraints involve interdependencies between objects that imply dependencies between the parameters of several objects. When you edit one of the interrelated parameters, the others also change. Editing parameters of an object that have no relationships with parameters of other objects has no effect on any parameters. When you delete one or several objects, the relationship disappears.

An example of relationships between objects is parallelism and perpendicularity of segments, straight lines, view arrows, and segments of a stepped cut line, equal length of segments or equal radius of circles. Slope angles of parallel segments are interdependent parameters, as parallelism of segments is identical to equality of their slope angles. If one of the segments with such a relationship is rotated, i.e. its slope angle is changed, the other segment will also be rotated. If one of the segments is shifted or scaled, i.e. its slope angle remains unchanged, the other segment will not change. If one of the segments is deleted, the other segment’s slope angle will become independent.

Relationships between parameters can be more complicated than equality of two parameters. For example, you can set a function determining a relation between parameters of several objects.

Another type of constraint is associativity of objects. Objects which are snapped to other objects during construction can be associative. In sketches such objects include dimensions; in graphic documents — dimensions, service designations, and hatches. Associative objects "remember" that they belong to a base object (segment, circle, another dimension, etc.) or to several objects. When editing base objects (for example, shifting or rotating them), associative objects are accordingly rebuilt. As a result, mutual location of the base object and the associated one is preserved.

While editing parameterized and associative objects, the image is rebuilt so that all the constraints applied to the objects are observed.

Parametric images can be used both independently (for example, in a drawing containing parametric views, in a sketch containing a solid section) and for insertion into other documents (drawings or fragments). A parametric image designed for insertion must be stored in a fragment (file with the extension frw) and have External variables.