I have written quite a bit of code that is directly or indirectly related to collision detection/resolution and physical simulation for games and renderers. On the real-time side: I have written an euler-integration physics engine with collision detection and resolution for 2D primitives that I used in a pinball game, and I have adapted many features of that engine into 3D for use in various tech demos. I have also written 2D rope and 3D cloth simulations employing spring-mass systems position-based dynamics, and created a demo of a hydra whose heads track a player using CCD Inverse Kinematics. On the offline side: I have implemented a BVH for acceleration of a software ray tracing renderer that also required me to write plenty of code for pinpointing collisions between rays and 3D primitives.