Graphics Engine In The Shadow Algorithm

Nowadays, as the development of the computer graphics and the higher speed of the computer hardware, the shadow rendering is becoming real-time and more believable than the old years. The shadow technology is becoming more essential in computer graphics. Shadow rendering often takes a lot of time and resources. So real-time shadow rendering is getting more important in computer graphics.For the limitation of the hardware, it was always rendering hard shadows in the past. But today soft shadow tech. is more popular to make virtual world trustful. As the development of the hardware, a special soft shadow algorithm with the programmable pipeline of the GPU, which is to render the umbra and the penumbra separately, will be given. Rendering the penumbra with Shadow Map algorithm is one special technology.First, some basic matrix transformation algorithm and some GPU programming and debugging technology are introduced.And then, some available shadow algorithms are analyzed and realized. Firstly, the planar projection shadow algorithm, which is always used to projection shadows on any plane, and used to demonstration often, is introduced. Secondly, the Shadow Volume algorithm is analyzed, whose FPS gets down as the growing of the number of the model or the complication of the models. At last, the Shadow Map technology is told, which has little relation with the number of models, but will be incorrectly displayed sometimes because the precision of the sampling of the shadow map.After all these, a real time way of rendering the soft shadow comes out spontaneously, which is mixed by the silhouette skills of the Shadow Volume, the Shadow Map algorithm and the Gouraud technology, which is used to render an Alpha texture. As the experiment tells, it will be real time, and can be used to general graphics engine.Direct3D and HLSL are used to render. Direct3D is popular on windows system, and HLSL is used to program GPU with Direct3D.The experimental results show that the algorithm reaches the goal of real-time shadow rendering.