CryEnginev渲染流程(by longlongway2012)

xiaoxiao2021-02-28  59

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。

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