"contact" - mkraska/meclib GitHub Wiki

[ "contact", "name", [x, y], [dx, dy], targetRef, lineLength, visible ]

Point-type support representing a frictionless contact between the sketched body and an environment object that gets cut away. Appears as a gray cross (normal + tangent line) once the referenced object is deactivated.

• "name" label, typeset in MathJax math mode (may be empty)
• [x, y] contact point
• [dx, dy] normal direction vector (need not be normalized); the tangent is perpendicular to it
• targetRef name (string) or 1-based index (integer) of the object that this contact replaces once cut away
• lineLength (optional, default 1) length of the gray cross indicating normal/tangent snap directions
• visible (optional, default true) whether the gray cross is ever drawn; it is only shown while the referenced object is deactivated

Status (for names/free body diagram matching) is derived automatically from the referenced object: "hide" (eligible for a reaction) once that object is deactivated, "show" otherwise.

See Feedback for "contact" for feedback functions in free body diagrams.