77 lines
3.0 KiB
Markdown
77 lines
3.0 KiB
Markdown
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---
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title: Untitled
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date: 2024-08-15 12:02:42
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excerpt:
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tags:
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rating: ⭐
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---
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# 前言
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- [UE5渲染--GPUScene与合并绘制](https://zhuanlan.zhihu.com/p/614758211)
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# 相关类型
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- Primitive：
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- C++的数据类型_FPrimitiveUniformShaderParameters_（PrimitiveUniformShaderParameters.h)
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- Shader的数据FPrimitiveSceneData（SceneData.ush)；
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- Instance：
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- C++的数据类型FInstanceSceneShaderData（InstanceUniformShaderParameters.h)
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- Shader的数据FInstanceSceneData（SceneData.ush)；
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- Payload：
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- C++数据类型FPackedBatch、FPackedItem（InstanceCullingLoadBalancer.h)
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- Shader的数据类型FPackedInstanceBatch、FPackedInstanceBatchItem（InstanceCullingLoadBalancer.ush)
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# DeferredShadingRenderer.cpp
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```c++
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Scene->GPUScene.Update(GraphBuilder, GetSceneUniforms(), *Scene, ExternalAccessQueue);
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for (int32 ViewIndex = 0; ViewIndex < Views.Num(); ViewIndex++)
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{
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FViewInfo& View = Views[ViewIndex];
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RDG_GPU_MASK_SCOPE(GraphBuilder, View.GPUMask);
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Scene->GPUScene.UploadDynamicPrimitiveShaderDataForView(GraphBuilder, *Scene, View, ExternalAccessQueue);
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Scene->GPUScene.DebugRender(GraphBuilder, *Scene, GetSceneUniforms(), View);
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}
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```
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## GPUScene数据更新
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```c++
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// 函数调用关系
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void FDeferredShadingSceneRenderer::Render(FRDGBuilder& GraphBuilder)
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{
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void FGPUScene::Update(FRDGBuilder& GraphBuilder, FScene& Scene, FRDGExternalAccessQueue& ExternalAccessQueue)
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{
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void FGPUScene::UpdateInternal(FRDGBuilder& GraphBuilder, FScene& Scene, FRDGExternalAccessQueue& ExternalAccessQueue)
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}
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}
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```
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### 2.2、更新PrimitiveData
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接下来，对标记为dirty的Primitive进行更新，更新逻辑为找到该Primitive在PrimitiveData Buffer里对应offset位置，对其进行更新。使用模板FUploadDataSourceAdapterScenePrimitives调用UploadGeneral()。
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初始化5类Buffer的上传任务TaskContext
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后面代码都是在对这个TaskContext进行初始化，然后启动任务，进行数据的上传。
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2.2.1、并行更新Primitive数据，将需要更新的PrimitiveCopy到Upload Buffer里，后续通过ComputeShader进行显存的上传然后更新到目标Buffer里；
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2.2.2、同理InstanceSceneData以及InstancePayloadData数据的处理。
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2.2.3、同理InstanceBVHUploader，LightmapUploader。
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2.2.4、最后都会调用每个Uploader的***End()方法进行GPU显存的更新***。
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总结：数据的上传都一样，将需要更新的数据Copy到对应的UploadBuffer对应的位置里，然后通过对应的ComputeShader进行更新到目标Buffer，在函数FRDGAsyncScatterUploadBuffer::End()里实现，截图：
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