Particle System Dynamics, Andrew Witkin of Pixar Animation Studios, SIGGRAPH 2003 Course Notes.

Summary:

This paper discusses the structure of a basic mass springs particle system, the forces that will act on the particles and how to define them, as well as a little information on collision detection and responce. 

Problem:

How does one set up a particle system to represent a mass-springs cloth model? 
What issues should one keep in mind when doing so?

Method:

The particle system described in this paper essentially keeps track of the current state of the particles (position and velocity) and can generate information on the forces for a given particle. The solver presented is a rough implementation of Euler's method. The paper also discusses the formula for generating information on the gravity force, viscous drag force, and the spring forces inside the cloth. These are all quite simple and are based on actual physics. The paper touches very briefly on energy functions, collision detection and responce, and possible projects and interfaces that could be implemented for this model. 

Key Ideas:

	1. The basic mass springs system is simple to understand and easy to implement.
	2. Particles store only their state and have a temporary buffer to accumulate their forces.
	3. Calculating the movement of the whole system over a time step can be done with simple vector operations. 
	4. The forces involved in this simulation are simple and physically based.

Contributions:

This paper is more of an explanatory, learning aid. It presents the mass springs model in a very simple format and provdes basic code that one could start from.