This is a rigid body simulation using XPBD as discussed in the paper "detailed rigid body simulation with XPBD". It is written in C++ and runs in the browser using webassembly. Collisions between the cubes are handled using GJK together with the expanding polytope algorithm (EPA) to get the contact points and normal. The axis aligned bounding boxes (AABBs) of each cube are stored in a spatial hash grid which is rebuild once per substep. This way, boxes are checked for collisions only if their AABBs overlap. The walls are checked separately, by computing if any of the vertices of the rigid body is behind any of them.

This is a simple demo was inspired by PBD Papers by Matthias Muller et. al. It shows simple simulation of many particles and some moving boundaries. Particle friction is simulated using two different approaches found in PBD papers.

This demo shows the curve of the mechanical energy (potential energy and kinetic energy) of the ball during the simulation..

The triple pendulum in 3d!

The triple pendulum in 3d with trail!