Granular material deposition for simulation and texturing

Dry granular materials are commonly needed in visual effects. To simulate a material involving individual grains, every granule must first be settled into place by running a pre-simulation. This pre-simulation can take minutes or hours, and the resulting look can be difficult to control. We introduce a faster, more directable method for depositing particles. We scatter granules in the desired area, guaranteeing that they are interpenetrating, then push them apart by means of penetration resolution such that they are in contact but not overlapping. This results in a natural, aperiodic layout of granules that mimics settled granular materials with little cost to production time. We also introduce particle shaders, a method for generating granular detail at render time.