Flow-noise en temps réel

Procedural textures, such as Perlin noise, enable us to achieve high quality, resolution independant static effects. Our research aims at providing real-time animation for such noise. Thus, we can enhance the apperance of fluids — especially geophysical fluids such as clouds, fire, water, lava, mud, etc. — by adding animated noise at small scales.

To achieve a realistic appearance, we must give the feeling of the flowing and swirling that are caracteristic of real flows. Flowing is obtained with advected textures, linked to a fluid solver. The main part of our work is simulating the swirling of the flow. We use flow-noise to add rotation to Perlin noise. Using a local measure of vorticity and Kolmogorov theory, we determine the amount of animation in the fluid at different scales. This ensures that our flow-noise has a physically correct spectrum.

Computing flow-noise is quite intensive ; however, we show how real-time framerates can be achieved with current GPUs. We highlight a number of GPU-specific issues and optimisations for our algorithm, and we include complete source code and documentation for our pixel shader.