Game Development Reference
Figure 8.3. Collision normals. Here, gray lines define the surface normal at the contact
vertex, and thick solid lines represent the rope and its “collision normal,” which forms an
angle with the surface normal.
large amount of things in a physics simulation, this test requires its fair share of
tolerances and tweaks to make it work in a plausible way. Nevertheless, now we
have a strained, frictionless rope; let's see how it can apply impulses to all objects
at once, within a single constraint.
Normals here are not the surface contact normal but just the bisectors of the
incoming and outgoing rope directions at a contact vertex.
d i - 1 - d i
d i - 1
Impulses at contact points (frictionless case).