This article presents a system to integrate verlet physics collision with preservation of impulse. Normally verlet physics annihilates a lot of energy from a system, which makes it very stable but also quite unrealistic. Additionally simple methods of preserving impulse yield very unstable systems, a limitation which can be overcome by two steps of integration, one for at-rest acceleration canceling, and one with impulse preservation.
In the previous post about integration methods, I took a look at gravity integration. Gravity is a good example of a soft constraint. It does not impose hard limits to movement of bodies. But what if we need hard constraints, for instance like steel beams? The following post explains how to implement hard constraints.
In this post I'm testing different integration methods for a gravity simulation. The results can be inspected interactively in the canvas tags that accompany each test. Hover with the mouse over the illustration to start its simulation or click the illustration to reset the simulation.
The header of this page features a couple flying dots in the Grey strip. They are drawn using a html5 feature called "canvas". Canvas is pretty cool, it makes a lot of things possible for which you had to use flash previously. This post is about how this works including lots of code and math.