Research & Implementation Of Real-time Cartoon Animation Of Smoke

Computer animation is an important research field in computer graphics, and 3D cartoon animation generated by computers is a hot topic in computer animation. In this paper, we present a practical framework to generate cartoon style animations of smoke at real-time frame rate based on the related previous work, including simulation of smoke, dynamic control of smoke and non-photorealistic rendering of smoke.Cartoon animation has two characteristic abstractions: motion abstraction and visual abstraction. Based on these two features, our framework consists of a smoke simulator and a cartoon renderer accordingly.In the simulation stage, we employ smoothed particle hydrodynamics (SPH) to model smoke as about 10~2~10~3 smoothed particles, and define the repulsive force on them. Meanwhile, other physical parameters such as velocity, air friction, wind and collision force are all defined on the particles directly.In the rendering stage, we first prerender each particle as an ellipsoid with a normal map and a depth map. We sample the normal map to get the normal vector of a pixel, and then calculate the dot product with the ordinary light source and an auxiliary light source at the viewing point. Finally, the depth map is sampled to get the depth value, which is used to modify the depth of each pixel on the billboard to eliminate the flicker problem. The rendering process is executed on the GPU entirely.Although the algorithm of simulation and rendering is simple and intuitive, it satisfies the features of cartoon animation quite well. In the most moderate scale scene, an impressive cartoon animation is generated with about a thousand particles at real-time frame rate.