Direct3D 12 尝鲜(四): 旋转的彩色立方体

小灰灰 2022-08-07 16:00 212阅读 0赞

###### (转载请注明出处) ######

有点时间没更新了，原因是找了一个多星期的bug结果发现是少了一次加法运算。。。。  
![Orz][]  
不过反正没人看也就没影响啦！\_(:3」∠)\_

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这次的目的是做一个旋转的彩色立方体:  
![color cube][]

这是自己在学D3D11的时候做过的一个例子，现在搬到D3D12上, 这次增加的内容有:

*  常量缓存
 *  深度缓存
 *  顶点/索引缓存
    
    1.  **常量缓存**, 常量缓存可以放一些GPU只读的数据, 这里就是存放的是转换矩阵，D3D12中，常量缓存是以256字节对齐的([D3D12\_CONSTANT\_BUFFER\_DATA\_PLACEMENT\_ALIGNMENT][D3D12_CONSTANT_BUFFER_DATA_PLACEMENT_ALIGNMENT]), 所以请注意.  
        这样可以创建一个常量缓存并[创建CBV绑定到一个DESCRIPTOR][CBV_DESCRIPTOR]上

// 创建常量缓存
        if (SUCCEEDED(hr)) {
            hr = m_pd3dDevice->CreateCommittedResource(
                &CD3D12_HEAP_PROPERTIES(D3D12_HEAP_TYPE_UPLOAD),
                D3D12_HEAP_MISC_NONE,
                &CD3D12_RESOURCE_DESC::Buffer(D3D12_CONSTANT_BUFFER_DATA_PLACEMENT_ALIGNMENT),
                D3D12_RESOURCE_USAGE_GENERIC_READ,
                nullptr,
                IID_ID3D12Resource,
                reinterpret_cast<void**>(&m_pCBufferMatrix)
                );
    
        }
        // 绑定到常量缓存视图
        if (SUCCEEDED(hr)) {
            D3D12_CONSTANT_BUFFER_VIEW_DESC cbvDesc = {};
            cbvDesc.BufferLocation = m_pCBufferMatrix->GetGPUVirtualAddress();
            cbvDesc.SizeInBytes = D3D12_CONSTANT_BUFFER_DATA_PLACEMENT_ALIGNMENT;
            m_pd3dDevice->CreateConstantBufferView(
                &cbvDesc,
                m_aCpuHandleCSU[CSU_MatrixCBuffer]
                );
        }

这部分代码中, 使用[D3D12\_HEAP\_TYPE\_UPLOAD][D3D12_HEAP_TYPE_UPLOAD]是因为我们每帧都要改写,这样比较方便, 相应的, 效率可能就会损失点.  
还有就是之前提到的把所有相同的DESCRIPTOR集中放到一起, 所以写了个简单的框架, 使用m\_aCpuHandleXXX数组存放的.  
我们在这里存放3个矩阵: 世界、视角、透视转换矩阵  
2. **深度缓存**, 深度缓存的作用就不用说了, 灵活使用可以获取到不错的效果, [创建DSV绑定到DESCRIPTOR][DSV_DESCRIPTOR]. 这里不使用模板, 仅仅使用深度:

// 创建深度缓存
        if (SUCCEEDED(hr)) {
            D3D12_RESOURCE_DESC resourceDesc = CD3D12_RESOURCE_DESC::Tex2D(
                DXGI_FORMAT_R32_TYPELESS, m_uBufferWidth, m_uBufferHeight,
                1, 1, 1, 0, 
                D3D12_RESOURCE_MISC_ALLOW_DEPTH_STENCIL,
                D3D12_TEXTURE_LAYOUT_UNKNOWN, 0
                );
            D3D12_CLEAR_VALUE dsvClearValue;
            dsvClearValue.Format = DXGI_FORMAT_D32_FLOAT;
            dsvClearValue.DepthStencil.Depth = 1.0f;
            dsvClearValue.DepthStencil.Stencil = 0;
            hr = m_pd3dDevice->CreateCommittedResource(
                &CD3D12_HEAP_PROPERTIES(D3D12_HEAP_TYPE_DEFAULT),
                D3D12_HEAP_MISC_NONE,
                &resourceDesc,
                D3D12_RESOURCE_USAGE_DEPTH,
                &dsvClearValue,
                IID_ID3D12Resource,
                reinterpret_cast<void**>(&m_pDepthBuffer)
                );
        }
        // 绑定深度缓存到DSV
        if (SUCCEEDED(hr)) {
            D3D12_DEPTH_STENCIL_VIEW_DESC dsvDesc = {};
            dsvDesc.ViewDimension = D3D12_DSV_DIMENSION_TEXTURE2D;
            dsvDesc.Format = DXGI_FORMAT_D32_FLOAT;
            dsvDesc.Texture2D.MipSlice = 0;
            dsvDesc.Flags = D3D12_DSV_NONE;
            /*no return*/m_pd3dDevice->CreateDepthStencilView(
                m_pDepthBuffer, &dsvDesc,
                m_aCpuHandleDSV[DSV_MainDSV]
                );
        }

感觉没什么可以说的, D3D12提供的Helper很方便, 默认值就行，详细的可以查看官方文档.  
3. **顶点/索引缓存**， 渲染一个立方体所需要的东西, 目前我们需要: 顶点颜色与顶点坐标, 索引就是三角索引了

// 创建带颜色的正方体
    auto SceneRenderer::CreateColoredCube(
        ID3D12Resource*& vibuffer,
        D3D12_VERTEX_BUFFER_VIEW& vbuffer_view,
        D3D12_INDEX_BUFFER_VIEW& ibuffer_view) noexcept -> HRESULT {
        HRESULT hr = S_OK;
        ID3D12Resource* pVIBuffer = nullptr;
        // 立方体的8个顶点 与相应颜色
        VertexColor vertices[] = {
                { DirectX::XMFLOAT3(-1.f, -1.f, -1.f), DirectX::XMFLOAT4(0.f, 0.f, 0.f, 1.f) },
                { DirectX::XMFLOAT3(-1.f,  1.f, -1.f), DirectX::XMFLOAT4(1.f, 0.f, 0.f, 1.f) },
                { DirectX::XMFLOAT3(1.f,  1.f, -1.f), DirectX::XMFLOAT4(0.f, 1.f, 0.f, 1.f) },
                { DirectX::XMFLOAT3(1.f, -1.f, -1.f), DirectX::XMFLOAT4(0.f, 0.f, 1.f, 1.f) },
                { DirectX::XMFLOAT3(-1.f, -1.f,  1.f), DirectX::XMFLOAT4(0.f, 1.f, 1.f, 1.f) },
                { DirectX::XMFLOAT3(-1.f,  1.f,  1.f), DirectX::XMFLOAT4(1.f, 1.f, 0.f, 1.f) },
                { DirectX::XMFLOAT3(1.f,  1.f,  1.f), DirectX::XMFLOAT4(1.f, 0.f, 1.f, 1.f) },
                { DirectX::XMFLOAT3(1.f, -1.f,  1.f), DirectX::XMFLOAT4(1.f, 1.f, 1.f, 1.f) }
        };
        // 立方体 6个面 12个三角面 36个顶点
        uint16_t indices[] = {
            0, 1, 2, 0, 2, 3,
            4, 5, 1, 4, 1, 0,
            7, 6, 5, 7, 5, 4,
            3, 2, 6, 3, 6, 7,
            1, 5, 6, 1, 6, 2,
            4, 0, 3, 4, 3, 7
        };
    
        // 创建顶点缓存-索引缓存共用缓冲区
        if (SUCCEEDED(hr)) {
            hr = m_pd3dDevice->CreateCommittedResource(
                &CD3D12_HEAP_PROPERTIES(D3D12_HEAP_TYPE_UPLOAD),
                D3D12_HEAP_MISC_NONE,
                &CD3D12_RESOURCE_DESC::Buffer(sizeof(vertices)+sizeof(indices)),
                D3D12_RESOURCE_USAGE_GENERIC_READ,
                nullptr,
                IID_ID3D12Resource,
                reinterpret_cast<void**>(&pVIBuffer)
                );
        }
        // 映射
        void* buffer = nullptr;
        if (SUCCEEDED(hr)) {
            hr = pVIBuffer->Map(0, nullptr, &buffer);
        }
        // 复制-取消映射-设置
        if (SUCCEEDED(hr)) {
            ::memcpy(buffer, vertices, sizeof(vertices));
            ::memcpy(
                reinterpret_cast<uint8_t*>(buffer)+ sizeof(vertices), 
                indices, sizeof(indices)
                );
            pVIBuffer->Unmap(0, nullptr);
            // 设置
            vbuffer_view.BufferLocation = pVIBuffer->GetGPUVirtualAddress();
            vbuffer_view.StrideInBytes = sizeof(VertexColor);
            vbuffer_view.SizeInBytes = sizeof(vertices);
            ibuffer_view.BufferLocation = vbuffer_view.BufferLocation + sizeof(vertices);
            ibuffer_view.Format = DXGI_FORMAT_R16_UINT;
            ibuffer_view.SizeInBytes = sizeof(indices);
            vibuffer = ::SafeAcquire(pVIBuffer);
        }
        ::SafeRelease(pVIBuffer);
        return hr;
    }

得益于D3D12/Win10的虚拟GPU地址, **我们可以将顶点缓存缓存与索引缓存一起申请, 提高效率.** 对应的输入布局:

// 输入布局
        D3D12_INPUT_ELEMENT_DESC inputLayout[] = {
            { "POSITION", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 0, D3D12_INPUT_PER_VERTEX_DATA, 0 },
            { "COLOR", 0, DXGI_FORMAT_R32G32B32A32_FLOAT, 0, sizeof(DirectX::XMFLOAT3), D3D12_INPUT_PER_VERTEX_DATA, 0 },
        };

其实颜色也是可以用3个浮点数就行, 这样每个节点就能节约1个浮点了.对应的shader就是:

// C Buffer 0 : 储存转换矩阵
    cbuffer MatrixBuffer : register (b0) {
        matrix worldMatrix;
        matrix viewMatrix;
        matrix projectionMatrix;
    };
    
    // VS 输入
    struct VertexInputType {
        float4 position     : POSITION;
        float4 color        : COLOR;
    };
    
    // VS 输出
    struct PixelInputType {
        float4 position     : SV_POSITION;
        float4 color        : COLOR;
    };
    
    // 处理
    PixelInputType ColorVertexShader(VertexInputType input) {
        PixelInputType output;
        // 坐标转换
        output.position = mul(float4(input.position.xyz, 1), worldMatrix);
        output.position = mul(output.position, viewMatrix);
        output.position = mul(output.position, projectionMatrix);
        // 直接输出
        output.color = input.color;
    
        return output;
    }
    
    // 像素着色器处理
    float4 ColorPixelShader(PixelInputType input) : SV_TARGET {
        return input.color;
    }

请注意, 因为都算是“固定管线”，所以我们在着色器里面使用的一切都要说明:  
这里使用了在b0寄存器上cbuffer.  
毕竟输入小，管线占用资源就少, 序列化RootSignature时提供的参数[D3D12\_ROOT\_SIGNATURE][D3D12_ROOT_SIGNATURE]表明了这个:

D3D12_ROOT_SIGNATURE rootSigDesc = D3D12_ROOT_SIGNATURE();
            D3D12_ROOT_PARAMETER params[1];
            D3D12_DESCRIPTOR_RANGE descRange[1];
            descRange[0].Init(D3D12_DESCRIPTOR_RANGE_CBV, 1, 0);
            params[0].InitAsDescriptorTable(lengthof(descRange), descRange);
            // 初始化
            rootSigDesc.NumParameters = lengthof(params);
            rootSigDesc.pParameters = params;
            rootSigDesc.Flags = D3D12_ROOT_SIGNATURE_ALLOW_INPUT_ASSEMBLER_INPUT_LAYOUT;

目前仅需一个DESCRIPTOR表即可，并且只有一个常量缓存视图(CBV), 所以才是**descRange\[0\].Init(D3D12\_DESCRIPTOR\_RANGE\_CBV, 1, 0);**

这次清空命令多了个清空深度缓存:

}
        // 执行清空命令
        if (SUCCEEDED(hr)) {
            this->SetResourceBarrier(m_pCmdClear, m_pTargetBuffer, D3D12_RESOURCE_USAGE_PRESENT, D3D12_RESOURCE_USAGE_RENDER_TARGET);
            m_pCmdClear->RSSetViewports(1, &view);
            float clearColor[4] = { 0.4f, 0.8f, 1.0f, 1.0f};
            m_pCmdClear->ClearRenderTargetView(
                m_aCpuHandleRTV[RTV_MainRTV],
                clearColor, nullptr, 0
                );
            m_pCmdClear->ClearDepthStencilView(
                m_aCpuHandleDSV[DSV_MainDSV], D3D12_CLEAR_DEPTH, 1.0f, 
                0, nullptr, 0
                );
            this->SetResourceBarrier(m_pCmdClear, m_pTargetBuffer, D3D12_RESOURCE_USAGE_RENDER_TARGET, D3D12_RESOURCE_USAGE_PRESENT);
            hr = m_pCmdClear->Close();
        }

刻画命令多了: 设置DESCRIPTOR表(对应管线), 与DESCRIPTOR堆(提供资源),以及设置顶点缓存和索引缓存:

// 执行命令
        if (SUCCEEDED(hr)) {
            ID3D12DescriptorHeap* heaps[] = {
                m_pCSUDescriptors
            };
            D3D12_RECT scissor = {};
            scissor.right = m_uBufferWidth;
            scissor.bottom = m_uBufferHeight;
            //
            this->SetResourceBarrier(m_pCmdDraw, m_pTargetBuffer, D3D12_RESOURCE_USAGE_PRESENT, D3D12_RESOURCE_USAGE_RENDER_TARGET);
            m_pCmdDraw->RSSetViewports(1, &view);
            m_pCmdDraw->RSSetScissorRects(1, &scissor);
            m_pCmdDraw->SetRenderTargets(m_aCpuHandleRTV + RTV_MainRTV, true, 1, m_aCpuHandleDSV + DSV_MainDSV);
            m_pCmdDraw->SetGraphicsRootSignature(m_prsPipeline);
            m_pCmdDraw->SetDescriptorHeaps(heaps, lengthof(heaps));
            m_pCmdDraw->SetGraphicsRootDescriptorTable(0, m_pCSUDescriptors->GetGPUDescriptorHandleForHeapStart());
            m_pCmdDraw->SetPipelineState(m_pPipelineState);
            m_pCmdDraw->IASetPrimitiveTopology(D3D_PRIMITIVE_TOPOLOGY_TRIANGLESTRIP);
            m_pCmdDraw->SetVertexBuffers(0, &m_cubeVBV, 1);
            m_pCmdDraw->SetIndexBuffer(&m_cubeIBV);
            m_pCmdDraw->DrawIndexedInstanced(36, 1, 0, 0, 0);
            this->SetResourceBarrier(m_pCmdDraw, m_pTargetBuffer, D3D12_RESOURCE_USAGE_RENDER_TARGET, D3D12_RESOURCE_USAGE_PRESENT);
            hr = m_pCmdDraw->Close();
    
        }

更新常量缓存直接修改即可, 会自动上传的:  
![cube][]

--------------------

代码下载地址: [点击这里][Link 1]

--------------------

[Orz]: /images/20220805/41c36fe2c0e7495ebec134ecede427b1.png
[color cube]: /images/20220805/02d5c74a72004336b181f58003bde2d0.png
[D3D12_CONSTANT_BUFFER_DATA_PLACEMENT_ALIGNMENT]: https://msdn.microsoft.com/en-us/library/windows/desktop/dn903792%28v=vs.85%29.aspx
[CBV_DESCRIPTOR]: https://msdn.microsoft.com/en-us/library/windows/desktop/dn788659%28v=vs.85%29.aspx
[D3D12_HEAP_TYPE_UPLOAD]: https://msdn.microsoft.com/en-us/library/windows/desktop/dn770374%28v=vs.85%29.aspx
[DSV_DESCRIPTOR]: https://msdn.microsoft.com/en-us/library/windows/desktop/dn788661%28v=vs.85%29.aspx
[D3D12_ROOT_SIGNATURE]: https://msdn.microsoft.com/en-us/library/windows/desktop/dn879479%28v=vs.85%29.aspx
[cube]: /images/20220805/5ea3b1355ccf45ceabf5eb5714ef6b06.png
[Link 1]: http://download.csdn.net/detail/dustpg/8610485