Creating Constraints with the Background Elements

You can create constraints on current sketch elements with background geometry with reference to its intersection or projection with the current sketch plane. When creating a constraint based on the background edge, a projection of the edge on the sketch plane is computed, by default. If an intersection exists, it is possible to select this intersection instead of projection and vice versa.

Before you begin: Create two sketches that intersect with each other. For example:
  1. From the Sketch section of the action bar, click Constraint.
  2. Select the center of the circle.
  3. Select the spline.

    An offset constraint is created. The constraint is displayed in the tree and the graphic area.

    In this case, you can constrain the current sketch element with the background geometry by creating a projection or an intersection constraint.

  4. Right-click the sketch element and perform any one of the following actions depending on the applied constraint:
    • Perform the following actions if the constraint is applied with respect to the projection of the external geometry with the current sketch plane.
    1. SelectSketch.x/Edge.x - Intersection.

      Note: The result of the projection of the background edge is displayed in a dotted curve in the graphic area.

    2. Click in the graphical area to validate the constraint.
      The constraint is created. The selected sketch element is now constrained with respect to the intersection of the external geometry with the current sketch plane.
    • Perform the following actions if the constraint is being applied with respect to the intersection of the external geometry with the current sketch plane.
    1. Select Sketch.x/Edge.x - Projection.

      Note: The result of the intersection of the background edge is displayed in yellow point in the graphic area.

    2. Click in the graphical area to validate the constraint.
      The constraint is created. The selected sketch element is now constrained with respect to the projection of the external geometry onto the current sketch plane.

    Notes:
    • If a projection or intersection operation is not valid for the selected sketch elements with the external geometry, then, the respective context menu option does not appear for that particular mode.
      • The constraint options for projection and intersection are available in the context menu only if you have selected at least one external element to constrain with the sketch elements.
    • If you want to constrain three elements together, you can select the required projection or intersection constraint for both external elements, whichever is applicable with the current set of geometry.

  5. Optional: Right-click the sketch element and select Sketch.x/Edge.x - Intersection or Sketch.x/Edge.x - Projection depending upon the available option.
    The constraint applied earlier (projection to intersection and vice versa) is swapped between the projected or intersected element and the current sketch.