Real-time Rendering Of Rain GPU-based In Marine Simulator

Atmospheric effects such as rain are important parts of natural environment. The restricted visibility caused by rain has a strong impact on safety of navigation. Rendering of rain in different intensity will improve simulation effect for restricted visibility in visual system of marine simulator. And it is also very important for creating realistic immersive marine environments.Real-time rendering of rain realistically is a hard work owing to the massivenumber of drops, complex movement of rain drops when falling down, and underdifferent viewpoints direction and lighting direction, sophisticated lighting appearanceof rain drops as a result of distortion in falling down. This paper develops a method ofsimulating rain GPU-based, A method is proposed building a library of textures storedin graphics memory according to the images of different viewpoints direction and light.This method builds a textures library by storing thousands of rain streak imagesdifferently into a texture object according to a designated architecture, during theinitialization stage. Each frame in rendering, calculates rain streak velocities andpositions based on velocities and positions of last frame and so on, then, renders thisdata into texture buffers. In the process of rending, we translate positions stored aspixels into vertexes array, and calculate indexes searching for texture through positionsand so on, then search for corresponding textures according to storage structure oftexture in vertex shader.Finally, we realized ten thousands order of magnitudes of rain streaks real-time rendering realistically, balanced the realistic rendering effects against real-time demands of marine simulator. We can simulate different rainfall intensity through adjust corresponding parameters, and moreover, the decline of visual system performance is slight, when the number of rain streaks is 20 thousands approximately.