Infer Constraints

This mode allows you to automatically constraints when creating sketch lines.

The types of automatically created constraints can be set in the system options ( Options > Constraints and Dimensions > Infer Constraints). By default, the Horizontal, Vertical, Coincident, Tangent and Perpendicular are automatically created. I.e. if any line is drawn tangentially to another, then a Tangent constraint is automatically created; if the end point of one line coincides with a point of another line or with the line itself, then a Coincident constraint is automatically created; Vertical and Horizontal constraints will be automatically created for all vertical and horizontal line segments. The Perpendicular constraint is created on all perpendicular segments, except for the case, when these segments are horizontal and vertical, since horizontal and vertical segments are already perpendicular to each other due to vertical and horizontal constraints.    

Example

Consider the same drawing as in the example of the Driving Dimensions section. The constraints on the lines were created there by the user. In fact, it is faster and easier to make constraints for such a drawing in automatic mode. To do this, after calling the command Sketch, before starting drawing, we enable the Infer Constraints <Ctrl>+<F2> mode in the snappings toolbar. Next, using the sketch options, create a drawing.

Create a circle, then create segments: the Tangent constraint gets automatically created for a segment tangent to a circle; since the segment is located vertically, a Verticality constraint is created; for the next segment the Horizontality constraint is automatically created and for the third segment, since it is also tangent to the circle, the Tangent constraint is created. For all points that coincide with other points or lines, the Coincidence constraint is automatically created.

We create a fillet using the Fillet command: four constraints are automatically created: two tangency and two coincidence. When using the Fillet command, the Trim Initial curves option was enabled. As a result, the intersection point of filleted segments, where the coincidence constraint was created, remains on the continuation of the trimmed segments. This constraint is not duplicating, since it would define the length of the segments before they intersect, if the trim option was not enabled. But for this sketch, neither the point nor the constraint itself is needed, so they can be removed.

Thus, using the automatic creation of constraints, a parametric sketch was created without the direct participation of the user in the creation of the parametrization. Further, it is possible to specify the driving dimensions of a parametric drawing, thereby eliminating the uncertainty of the constructions. Position of the sketch in relation to the LCS origin will be defined by the Fix constraint created for the center point of the circle.