Great to hear that. I hope you will also commit a very simple example, like 2 of those bumping into each other. > The snow grains are not "clean" polyhedrons and not convex. Sometimes > they have stupid faces nearly facing each other. I made the code to be > slower but correct, it was easier than cleaning all stupid faces (and > it still would remain concave). So it will work very good with > convex polyhedrons, and it will work acceptably with concave > polyhedrons. > AFAIK the common solution is to cut the shape into parts that are convex, since convex shapes are mathematically easier to handle. > When detecting collision I am going to iterate over all points from > one polyhedron checking if it is inside another polyhedron and > vice-versa. I'll have a list of polyhedron points that are inside of > each other. I'm going to assume that there is a plane of contact > which is somewhere in the middle of all those points. From that get a > penetration depth and normal of the contact, then it can go straight > to our CohseiveFrictionalContactLaw.... > There are sophisticated algorithms for detecting triangular surface collisions (see httpo://gts.sf.net for some references). For such complicated shapes, though, what folks in Glasgow do (and what I tried with tetraheda) is to treat the intersection as volume, i.e. compute volume and direction in which this volume is the thinnest (that is the direction of repulsive force); I used exact code for that (which is - who knows - maybe incorrect: extra/tetra), Bicanic &co in Glasgow get the direction from some averages over normals of planar elements involved in the collision. > And is much slower than spheres, so you can forget about simulations > with 5000 polyhedrons, anyway. > I bet you can forget simulations with 500 polyhedra as well ;-) Do you have some benchmarks on that, BTW?
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