A method for use in computer graphics includes receiving data representative of a plurality of particles. For each particle, the method further includes calculating a time at which a collision will occur based on a current trajectory of the particle. For pairs of particles that will collide with each other, another operation includes changing a direction of the particles to avoid a collision, wherein the changed directions approximate directions that would result from the collision. For particles in static contact, another operation includes allowing particles to push each other without bouncing. For particles in static contact that were previously moved by being pushed, the method also does not allow the particles to move during future collisions occurring during a time step.