D3D11之缓存更新(update buffer)

来源：互联网发布：浙江基层网络直报编辑：程序博客网时间：2024/06/07 14:58

话说这两天我写程序遇到一个bug，是关于如何创建的ID3D11Buffer的应该以一种怎样的方式在每帧渲染进行缓存资源的更新

我总结为下:

第一,当buffer是CPU访问写并且是动态的时候

//填充(顶点)缓存形容结构体和子资源数据结构体,并创建顶点缓存(这里用的是动态缓存)D3D11_BUFFER_DESC vertexBufferDesc;vertexBufferDesc.Usage = D3D11_USAGE_DYNAMIC;vertexBufferDesc.ByteWidth = sizeof(Vertex) * mVertexCount;vertexBufferDesc.BindFlags = D3D11_BIND_VERTEX_BUFFER;vertexBufferDesc.CPUAccessFlags = D3D11_CPU_ACCESS_WRITE;vertexBufferDesc.MiscFlags = 0;vertexBufferDesc.StructureByteStride = 0;

这里此时每帧进行该缓存资源的更新应该用MAP和UMAP进行资源更新vertexBufferDesc.Usage = D3D11_USAGE_DYNAMIC;vertexBufferDesc.CPUAccessFlags = D3D11_CPU_ACCESS_WRITE;

//锁定顶点缓存为了可以进行写入（动态缓存不能用UpdateSubResources写入）D3D11_MAPPED_SUBRESOURCE mappedResource;HR(d3dDeviceContext->Map(md3dVertexBuffer, 0, D3D11_MAP_WRITE_DISCARD, 0, &mappedResource));//获取指向顶点缓存的指针Vertex* verticesPtr;verticesPtr = (Vertex*)mappedResource.pData;//把数据复制进顶点缓存memcpy(verticesPtr, (void*)vertexs, (sizeof(Vertex) * mVertexCount));//解锁顶点缓存d3dDeviceContext->Unmap(md3dVertexBuffer, 0);

第二,当buffer不是CPU访问写并且是默认的时候，用updatesubResouce

//,设置(常量)缓存形容结构体,并创建常量缓存D3D11_BUFFER_DESC matrixBufferDesc;ZeroMemory(&matrixBufferDesc, sizeof(matrixBufferDesc));matrixBufferDesc.Usage =D3D11_USAGE_DEFAULT;  //缓存        matrixBufferDesc.ByteWidth = sizeof(CBMatrix);   //结构体大小,必须为16字节倍数        matrixBufferDesc.BindFlags = D3D11_BIND_CONSTANT_BUFFER;        matrixBufferDesc.CPUAccessFlags = 0;  //CPU访问写        matrixBufferDesc.MiscFlags = 0;       matrixBufferDesc.StructureByteStride = 0;       HR(d3dDevice->CreateBuffer(&matrixBufferDesc, NULL, &mCBMatrixBuffer));      这里 matrixBufferDesc.Usage =D3D11_USAGE_DEFAULT;  //缓存           matrixBufferDesc.CPUAccessFlags = 0;  //CPU访问写

CBMatrix cb;XMMATRIX worldMa = XMMatrixTranspose(worldMatrix);XMMATRIX viewMa = XMMatrixTranspose(viewMatrix);XMMATRIX ProjMa = XMMatrixTranspose(ProjMatrix);cb.mWorldMatrix = worldMa;cb.mViewMatrix = viewMa;cb.mProjMatrix = ProjMa;d3dDeviceContext->UpdateSubresource(mCBMatrixBuffer, 0, NULL, &cb, 0, 0);//上面创建Buffer设置的标志位不一样，更新资源的方式也不一样，如果不按指定方式更新资源将会造成资源无法写入缓存的后果

更具体的等我水平提高研究过在补充后续内容,更新每帧动态变化的尽量还是用MAP和UMAP吧

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