The collision detection system is still moving along.  I can now test a sphere against an arbitrary triangle and if there is a collision the sphere simply stops.  This works whether the sphere hits the face, vertices, or edges of the triangle.  I also made a simple test case with the sphere moving against a SphereGeometry mesh in THREE.js.  This just basically involved looping through all of the faces of the sphere to test for collisions.  That simple test seems to be working but I’m reserving judgment until I have done much more testing.  Specifically it would be really nice if I could load an object modeled in Blender with a custom, hidden collision cage and see if that works.  That’s the ultimate goal since I don’t want the collision system to test against the relatively complicated geometry of the objects visible in the world, but rather against a set of hidden, simpler geometries custom made for each object.  I think this should be fairly straightforward to pull off.

The next step, after I’ve tested with some other objects, is to implement collision response.  Right now if the sphere hits an object it just stops.  For a game, when the sphere hits an object it needs to slide along the surface of that object.  The paper I’m following includes a collision response code listing, so hopefully converting it over to Javascript will be pretty easy as well.