CryEngine 渲染流程

渲染涉及的线程： MainThread、RenderThread、CullingThread和JobThread。  MainThread： 用于控制渲染流程  RenderThread: 用于渲染底层图形元素  CullingThread：用于计算裁剪  JobThread： 用于协同以上线程的通信

线程协同的序列图

Cull Job,注册Culling任务：

DECLARE_JOB("CheckOcclusion", TOcclusionCheckJob, NAsyncCull::CCullThread::CheckOcclusion); DECLARE_JOB("PrepareOcclusion", TOcclusionPrepareJob, NAsyncCull::CCullThread::PrepareOcclusion); DECLARE_JOB("PrepareOcclusion_ReprojectZBuffer", TOcclusionPrepareReprojectJob, NAsyncCull::CCullThread::PrepareOcclusion_ReprojectZBuffer); DECLARE_JOB("PrepareOcclusion_ReprojectZBufferLine", TOcclusionPrepareReprojectLineJob, NAsyncCull::CCullThread::PrepareOcclusion_ReprojectZBufferLine); DECLARE_JOB("PrepareOcclusion_ReprojectZBufferLineAfterMerge", TOcclusionPrepareReprojectLineJob2, NAsyncCull::CCullThread::PrepareOcclusion_ReprojectZBufferLineAfterMerge); DECLARE_JOB("PrepareOcclusion_RasterizeZBuffer", TOcclusionPrepareRasterizeJob, NAsyncCull::CCullThread::PrepareOcclusion_RasterizeZBuffer); 裁剪处理：  MainThread中调用：  C3DEngine::PrepareOcclusion  |  CObjManager::PrepareCullbufferAsync  |  CCullThread::PrepareCullbufferAsync –> TOcclusionPrepareJob job; // 从主线程创建任务，任务则将从JobThread线程执行，此后每个Job结束后，又创建新的Job向下推进：  | ，  CCullThread::PrepareOcclusion –> TOcclusionPrepareReprojectJob job;  |  CCullThread::PrepareOcclusion_ReprojectZBuffer –> TOcclusionPrepareRasterizeJob job;  |  CCullThread::PrepareOcclusion_ReprojectZBufferLine –> RASTERIZER.ReprojectHWDepthBuffer;TOcclusionPrepareReprojectLineJob2 job;  |  CCullThread::PrepareOcclusion_ReprojectZBufferLineAfterMerge –> RASTERIZER.ReprojectHWDepthBufferAfterMerge TOcclusionPrepareRasterizeJob job;  |  CCullThread::PrepareOcclusion_RasterizeZBuffer –>TOcclusionCheckJob job;  |  CCullThread::CheckOcclusion

以上流程，大体思路是，用当前相机生成一个裁剪视锥和深度缓存，通过TestAABB，将模型的深度信息写入深度缓存（类似于实现zbuffer深度绘制算法）。  除此，CryEngine还有其OCM处理流程（OCM Occlusion Mesh查询遮挡模型)，通过加载预先生成的OCM模型，可以快速裁剪。