對純HLSL和C++的效果框架「ConstructGSWithSO」

Question

如何將這種技術（從nVidia InstancedTseselation示例）轉換爲純HLSL + DirectX 11 C++代碼？

float4 PreprocessedLoDVS(uint id : SV_InstanceID, uniform int method) : LODS 
{ 
    float4 tessLevel; 
    if (method == 1) //Gregory 
    { 
     float3 positionControlPoints[20]; 
     // 8  9  10  11 
     // 12 0\1  2/3 13 
     // 14 4/5  6\7 15 
     // 16 17  18  19 
     LoadGregoryPositionControlPoints(id, positionControlPoints); 
     tessLevel.x = evaluateEdgeLoD(positionControlPoints[16], positionControlPoints[14], positionControlPoints[12], positionControlPoints[8]); 
     tessLevel.y = evaluateEdgeLoD(positionControlPoints[19], positionControlPoints[15], positionControlPoints[13], positionControlPoints[11]); 
     tessLevel.z = evaluateEdgeLoD(positionControlPoints[16], positionControlPoints[17], positionControlPoints[18], positionControlPoints[19]); 
     tessLevel.w = evaluateEdgeLoD(positionControlPoints[8], positionControlPoints[9], positionControlPoints[10], positionControlPoints[11]); 
    } 
    else if (method == 0) { //Regular 
     float3 positionControlPoints[16]; 
     // 0  1  2  3 
     // 4  5  6  7  
     // 8  9  10 11 
     // 12 13 14 15 
     LoadRegularControlPoints(id, positionControlPoints); 
     tessLevel.x = evaluateEdgeLoD(positionControlPoints[ 0], positionControlPoints[ 4], positionControlPoints[ 8], positionControlPoints[12]); 
     tessLevel.y = evaluateEdgeLoD(positionControlPoints[ 3], positionControlPoints[ 7], positionControlPoints[11], positionControlPoints[15]); 
     tessLevel.w = evaluateEdgeLoD(positionControlPoints[ 0], positionControlPoints[ 1], positionControlPoints[ 2], positionControlPoints[ 3]); 
     tessLevel.z = evaluateEdgeLoD(positionControlPoints[12], positionControlPoints[13], positionControlPoints[14], positionControlPoints[15]); 
    } 
    else if (method == 2) { //Bezier 
     float3 positionControlPoints[16]; 
     // 0  1  2  3 
     // 4  5  6  7  
     // 8  9  10 11 
     // 12 13 14 15 
     LoadBezierPositionControlPoints(id, positionControlPoints); 
     tessLevel.x = evaluateEdgeLoD(positionControlPoints[ 0], positionControlPoints[ 4], positionControlPoints[ 8], positionControlPoints[12]); 
     tessLevel.y = evaluateEdgeLoD(positionControlPoints[ 3], positionControlPoints[ 7], positionControlPoints[11], positionControlPoints[15]); 
     tessLevel.z = evaluateEdgeLoD(positionControlPoints[12], positionControlPoints[13], positionControlPoints[14], positionControlPoints[15]); 
     tessLevel.w = evaluateEdgeLoD(positionControlPoints[ 0], positionControlPoints[ 1], positionControlPoints[ 2], positionControlPoints[ 3]); 
    } 
    else if (method == 3) { //Pm 
     //   18 14 13 12        
     //   19   8   
     //   20   7    
     //   0 1 2 6     
     float3 positionControlPoints[24]; 
     LoadPmControlPoints(id, positionControlPoints); 
     tessLevel.x = evaluateEdgeLoD(positionControlPoints[ 0], positionControlPoints[20], positionControlPoints[19], positionControlPoints[18]); 
     tessLevel.y = evaluateEdgeLoD(positionControlPoints[ 6], positionControlPoints[ 7], positionControlPoints[ 8], positionControlPoints[12]); 
     tessLevel.z = evaluateEdgeLoD(positionControlPoints[18], positionControlPoints[14], positionControlPoints[13], positionControlPoints[12]); 
     tessLevel.w = evaluateEdgeLoD(positionControlPoints[ 0], positionControlPoints[ 1], positionControlPoints[ 2], positionControlPoints[ 6]); 
    } 
    else { 
     tessLevel=float4(2,2,2,2); 
    } 
    return tessLevel; 
} 

technique10 LoDRegularTechnique 
{ 
    pass P0 
    { 
     SetDepthStencilState(DisableDepthWrites, 0); 

     SetVertexShader(CompileShader(vs_4_0, PreprocessedLoDVS(0))); 
     SetGeometryShader(ConstructGSWithSO(CompileShader(vs_4_0, PreprocessedLoDVS(0)), "LODS.xyzw")); 
     SetPixelShader(NULL); 
    } 
} 

PreprocessedLoDVS看起來像往常一樣頂點着色器，除了「LODS」簽名，以及有關幾何着色器是什麼？

Answer 1

這link解釋它非常好，但基本上總結。

編譯着色器到斑點，使用PreprocessedLoDVS和vs_4_0作爲輪廓

創建流輸出佈局，這是D3D11_SO_DECLARATION_ENTRY陣列，這將是LODS語義與4級的組件。

創建使用CreateGeometryShaderWithStreamOut

創建D3D11_BIND_STREAM_OUTPUT標誌的緩衝區（就像您創建任何其他緩衝你的頂點着色器，從樣本您還需要着色資源標誌，因爲你需要SRV綁定回爲緩衝區輸入）。

綁定這個緩衝流輸出（使用SOSetTargets）

設置你的頂點着色器流水線，做你的繪圖調用。