This post is somewhat a description of what I’ve been doing recently. This week I’ve been reading cloth simulation papers to stay a bit away from rigid body dynamics since it is a well solved problem as discussed by the community. Last week I ended up finishing an implementation of contact point clustering using k-means. My experiments have shown that the optimization described in the excelent GPG4 article is available just to show how things got started. However, it can generate good results even if implemented naively, still leaving open doors for more optimization, such as the use of hysteresis to avoid jittering and the like. The video below was one of the first tests that showed some acceptable, still not plausable though, results.

# Category Archives: Collision

# Building a Half-Edge Mesh from a Triangle List

The problem is to build a polygonal mesh from a triangle list efficiently. A solution is important specially when building or testing physics engines. The method below shows a possible solution. This can be done without needing the additional storage and processing cost of keeping a list of half-edges for a given face during its addition which would be linked at the end of the addition in that case.

# Fast Segment-AABB Collision Detection

Let’s say we need to compute the intersection point and normal from a line segment to an axis-aligned bounding box (AABB) bounds, and we neither want to perform expensive plane computations nor keep the AABB boundaries as an intersection of 6 axis-aligned planes (as it is a waste of memory). A quick way to do that is by evaluating the slab plane equation for each axis-aligned plane of the AABB.

# Bounce Lite Update

I’ve added two joint types to Bounce Lite. Ball-in-socket, and revolute with angle limits. Bounce Lite is available at its repository: here. There is a video below showing how five revolute joints can be used to simulate a small ragdoll.

# Bounce Lite Release

I’m happy for distributing Bounce Lite, a portable 3D physics engine for games:

https://github.com/irlanrobson/Bounce-Lite

Bounce Lite is available at its GitHub repository. It is the second physics engine that I (Irlan) have written and the first that is publically distributed.