A naive particle system that every generated particle will fly to a target position and form a 3D model eventually. This simple particle system demo form a bunny. The bunny model is modified from the Bullet-Physics open source physics engine (bunnyMesh.h). The render is basically some OpenGL call, and each particle is drawn with gluSolidSphere. The color of each particle is base on the position [x, y, z] (so that each coordinate will map to range [0, 1], which eventually becomes the color value [red, green, blue]).
If you can’t see the 3D model very well, here is another version which shows up the model’s mesh frame line: