Rendering For The Big Outdoor Scene Of 3D Game With GPU Optimization

In the context of the financial crisis, many industries are in recession。The game industry is still maintained rapid growth, so the development of the game industry has some positive effects to resist the financial crisis. Currently the 2D games are already quite mature, however the 3D gaming is booming development. In the massively multiplayer online 3D game, the rendering for outdoor scene is very important. In this paper, combined the characteristics of GPU, the main study was focused on the terrain rendering of outdoor scenes, the management of the outdoor scene objects and the simulation of light and shadow。1. Rendering for terrainIn this paper, a more suitable algorithm for 3D game terrain real-time rendering is put forward based on Geometry Clipmaps algorithm and combined with 3D games. In this algorithm, the entire terrain can be rendered through only one Draw Call by improving the structure of grid and the organizational structure of the index, which can take full advantage of GPU. And by increasing the index of vertices in the rougher adjacent level, the issue of crack and jumping can be resolved. Using alpha blend texture to control the location and weight of the texture of terrain, it makes the control of color texture more flexible.2. Management of the outdoor scenes'objectsThe scene graph algorithms are used to manage the scene object. Combined with Axis Aligned Bounding Box (AABB), the quad-tree algorithm is used to subdivide the space of the scene, which can faster cull non-visible objects and speed collision detection. When rendering for the visible objects, the objects are sorted and grouped by their render state and material properties, in order to reduce the switch of rendering state and increase the rendering speed. For those objects with many quantity and similar properties, such as grass, instancing technology is used to render these objects. Instancing technology can render these objects only with one Draw Call, and save the graphics memory and the system memory. 3. The simulation of the light and shadowFor the simulation of scene, this paper's study is focused on the shadows and bloom effects. Compared with the shadow volumes, shadow maps have been adopted as a basis for shadow rendering. By improving the Shadow Maps algorithm, a perfect combination of CSM and the VSM is to solve large-scale scene dynamic shadows aliasing problem。The technique of blooming used to simulate HDR effects to make the scene brighter.