Last week, I finished setting up the quad tree given a heightfield. This was a big step, because this week I was able to start implementing collision tests. The first one is from a ray. I started this week by implementing line into box algorithm (using the slab method), and then line into triangle (Möller–Trumbore) algorithm. Using the box intersection test, I was able to find the quad tree nodes that are intersected by the ray. After, I use Bresenhaum's line drawing algorithm to get the heightmap elements that are intersected by the ray. Finally, using line into triangle I find the intersection between the ray and the triangles at those heightfield elements. Future collision tests will most likely follow the same format: first a box intersection test and then a triangle intersection test. Next week, I will focus on implementing collision tests from sphere and box. See you then!