The first version of Bounce has been pushed to the following git repository: https://github.com/irlanrobson/bounce. Bounce is a 3D physics engine for games and interactive applications and hopefully will be a fun project to work on.

# Author Archives: Irlan Robson

# 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.

# Distance Constraint Derivation

Sometimes it’s desired to have a distance constraint. That constraint assumes a choosen separation distance for two points fixed in two bodies. I’ve written a derivation for it in 3D and shared here. An implementation should be pretty simple since we have minimally one Jacobian and solve a 1D linear system. Here is an example which you can use in your own projects.

# 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.

# Keyboard Input for Fixed-Time Step Games

Suppose we’re using a fixed-time step to update the game and we’re at the begin of a new frame. Then, the keyboard input events that were fired are requested and handled via callbacks or similar, making a character to jump or shoot in an enemy. What is the problem with that?

# Custom Mesh File (.bin)

Binary files are the game industry standard format for streaming data from disk to memory at engine run-time because they can be easily interpreted.

# 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.