Hardware Accelerated Particle Systems

Particle systems have long been recognized as an essential building block for detail-rich and lively visual environments. Physically correct particle systems (PS) are designed to add essential properties to the virtual world. Over the last decades they have been established as a valuable technique for a variety of applications, e.g. deformable objects like cloth and volumetric effects.

CPU-implementations can handle up some 10,000 particles in real-time simulations and are mostly limited by the transfer of particle data from the main processor to the graphics hardware (GPU) for rendering. This work introduces a full GPU implementation using fragment shaders of both the simulation and rendering of a dynamically-growing particle system. Such an implementation can render up to 1 million particles in real-time on recent hardware. The massively parallel simulation handles collision detection and reaction of particles with objects for arbitrary shape. The collision detection is based on depth maps that represent the outer shape of an object. The depth maps store distance values and normal vectors for collision reaction. Using a special texture-based indexing technique to represent normal vectors, standard 8-bit textures can be used to describe the complete depth map data. Alternately, several depth maps can be stored in one floating point texture.

In addition, a GPU-based parallel sorting algorithm is introduced that can be used to perform a depth sorting of the particles for correct alpha blending.