General Parametric Curves

How to use parametric curves. One useful application of parametric curves is the case when the sketch contains fixed curves with unsupported geometry type. For example, a planar sketch can be created in the context of 3D CAD model, and then the sketch can receive 3D curve projections of arbitrary form from it. The projection curves that are included in the constraint system as parametric curves permit to link sketch geometry to projection objects. Parametric curves can also be used to layout drawings with the fragments produced by projecting the geometry from 3D models that keep an associative link with it.