标签：天空 pRenderer 实现 pSkybox register 纹理 DX12 opaquePSODesc D3D12

前言

本篇将展示如何使用DX12实现天空盒

创建dds立方体贴图

微软官方提供了一个命令行工具Texassemble，该工具可以将输入的几个图片转换为GPU可识别的DDS贴图，如立方体贴图

语法

texassemble <command>
    [-r] [-flist <filename>]
    [-w width] [-h height] [-f format]
    [-if filter] [-srgb | -srgbi | -srgbo]
    [-sepalpha] [-nowic] [-wrap | -mirror] [-alpha]
    [-o <outputfile>] [-l] [-y] [-dx10] [-tonemap]
    [-nologo]
    [-fl feature-level]
    [-bgcolor]
    [-swizzle rgbamask]
    [-stripmips]
    <file-name(s)>

常用指令：

file-name ：生成的dds、tga、hdr等格式的纹理名称
cube：创建一个cubemap，必须有六张图片，顺序为+x, -x, +y, -y, +z, -z
cubearray：创建一个cubmap数组
array：创建一个1D/2D的纹理数组，至少有两张图片
-w：输出纹理的宽
-h：输出纹理的高
-f：输出纹理的格式
-o：输出的纹理名。默认为".DDS"

例子

要点

立方体贴图用 6 幅二维纹理图像构成一个以原点为中心的纹理立方体，每个 2D 纹理是一个立方体的一个面
在D3D中，立方体图是一个含有6个元素构成的纹理数组，从索引0~5依次是+x,-x,+y,-y+z,-z。在使用texassemble创建立方体贴图时，按照对应顺序写入即可
对立方体贴图进行采样时和2d贴图有些许差别，需要使用3d的方向向量来查找纹理坐标，这是因为纹理坐标(s, t, r)被当作方向向量看待，每个纹素(texel)都表示从原点所看到的纹理立方体上的图像
确定纹理坐标：选择具有最大绝对值的纹理坐标对应的相应的面

如，对于给定的矢量(−3.2, 5.1, −8.4)，就选择-Z 面，而对剩下的两个坐标除以最大绝对值坐标的绝对值，即 8.4。那么就将剩下的两个坐标的范围转换到了-1 到 1，然后重映射到[0，1]范围
所谓天空盒其实是对一个超级大的球体进行纹理贴图，并且球体始终以摄像机作为原点，这样才不会露馅

绘制天空盒

生成球体

Model::GeometryGenerator geoGen;
Model::GeometryGenerator::MeshData box = geoGen.CreateBox(1.f, 1.f, 1.f, 5);

// GeometryGenerator'draw
{
    auto pDraw = std::make_unique<Model::Geometrie::Draw>();

    pDraw->baseVertex = (UINT)totalVertex.size();
    pDraw->startIndex = (UINT)totalIndex.size();
    pDraw->indexCount = (UINT)box.Indices32.size();

    m_draws.push_back(std::move(pDraw));

    totalVertex.insert(totalVertex.end(), box.Vertices.begin(), box.Vertices.end());
    totalIndex.insert(totalIndex.end(), box.Indices32.begin(), box.Indices32.end());
}

加载立方体纹理

LoadDDSTextureFromFile()会自动识别cube纹理，并存储它

// sky box
{
    auto pSkybox = std::make_unique<Core::Texture>();

    pSkybox->name = "skybox";
    pSkybox->fileName = Util::UTF8ToWideString("ModelFile/skybox/skybox.dds");
    OutputDebugStringA("ModelFile/skybox2/skybox.dds");

    ThrowIfFailed(LoadDDSTextureFromFile(
        m_device.Get(),
        pSkybox->fileName.c_str(),
        &pSkybox->defaultTexture,
        pSkybox->ddsData,
        pSkybox->subResources
    ));

    Core::CreateD3DResource(m_device.Get(), m_commandList.Get(), pSkybox->subResources, pSkybox->defaultTexture, pSkybox->uploadTexture);

    m_cubemaps[pSkybox->name] = std::move(pSkybox);
}

球体材质

// cubemap's material
{
    auto pMaterial = std::make_unique<Core::Material>();

    int index = m_models.size();
    pMaterial->name = "skybox";
    pMaterial->materialCBIndex = index;
    pMaterial->diffuseSrvHeapIndex = 2 * index;
    pMaterial->numFramesDirty = FrameCount;
    pMaterial->specualrShiness = 64;
    pMaterial->ambientAlbedo = 0.1;

    m_materials.push_back(std::move(pMaterial));
}

draw call项

{
    auto pRenderer = std::make_unique<Core::Renderer>();

    // 非常大的球体
    XMStoreFloat4x4(&pRenderer->world, DirectX::XMMatrixScaling(5000.f, 5000.f, 5000.f));
    pRenderer->objectIndex = i;
    pRenderer->numFramesDirty = FrameCount;
    pRenderer->pGeometry = m_geometries[0].get();
    pRenderer->pMaterail = m_materials[i].get();
    pRenderer->PrimitiveType = D3D_PRIMITIVE_TOPOLOGY_TRIANGLELIST;
    pRenderer->indexCount = m_draws[i]->indexCount;
    pRenderer->startIndex = m_draws[i]->startIndex;
    pRenderer->baseVertex = m_draws[i]->baseVertex;

    m_renderLayers[(int)Core::RenderLayer::Sky].push_back(pRenderer.get());
    m_allRenderers.push_back(std::move(pRenderer));
}

SRV

// create a const buffer view(CBV) descriptor heap
D3D12_DESCRIPTOR_HEAP_DESC cbvSrvHeapDesc = {};
cbvSrvHeapDesc.NumDescriptors = m_diffuseTextures.size() + m_specularTextures.size() + m_cubemaps.size();
cbvSrvHeapDesc.Type = D3D12_DESCRIPTOR_HEAP_TYPE_CBV_SRV_UAV;
cbvSrvHeapDesc.Flags = D3D12_DESCRIPTOR_HEAP_FLAG_SHADER_VISIBLE;
ThrowIfFailed(m_device->CreateDescriptorHeap(&cbvSrvHeapDesc, IID_PPV_ARGS(&m_cbvSrvHeap)));
NAME_D3D12_OBJECT(m_cbvSrvHeap);

CD3DX12_CPU_DESCRIPTOR_HANDLE hSRVDescriptor(m_cbvSrvHeap->GetCPUDescriptorHandleForHeapStart());

D3D12_SHADER_RESOURCE_VIEW_DESC srvDesc{};
srvDesc.ViewDimension = D3D12_SRV_DIMENSION_TEXTURE2D;
srvDesc.Shader4ComponentMapping = D3D12_DEFAULT_SHADER_4_COMPONENT_MAPPING;
srvDesc.Texture2D.MostDetailedMip = 0;  // the index of the most detailed mipmap level to use
srvDesc.Texture2D.ResourceMinLODClamp = 0.f;    // min mipmap level that you can access. 0.0f means access all of mipmap levels

// cubemap texture
{
    auto pCurrTexture = m_cubemaps["skybox"]->defaultTexture;

    srvDesc.ViewDimension = D3D12_SRV_DIMENSION_TEXTURECUBE;
    srvDesc.TextureCube.MostDetailedMip = 0;
    srvDesc.TextureCube.MipLevels = pCurrTexture->GetDesc().MipLevels;
    srvDesc.Format = pCurrTexture->GetDesc().Format;

    m_device->CreateShaderResourceView(pCurrTexture.Get(), &srvDesc, hSRVDescriptor);

    hSRVDescriptor.Offset(1, m_cbvSrvDescriptorSize);
}

PSO

由于需要先绘制模型，再绘制天空盒(天空盒的深度测试和模型的不同)，因此需要两个shader文件和两个PSO

m_shaders["MainVS"] = CompileShader(GetAssetFullPath(L"MainVS.hlsl").c_str(), nullptr, "main", "vs_5_1");
m_shaders["MainPS"] = CompileShader(GetAssetFullPath(L"MainPS.hlsl").c_str(), nullptr, "main", "ps_5_1");

m_shaders["CubemapVS"] = CompileShader(GetAssetFullPath(L"CubemapVS.hlsl").c_str(), nullptr, "main", "vs_5_1");
m_shaders["CubemapPS"] = CompileShader(GetAssetFullPath(L"CubemapPS.hlsl").c_str(), nullptr, "main", "ps_5_1");

// opaque PSO
D3D12_GRAPHICS_PIPELINE_STATE_DESC opaquePSODesc = {};

opaquePSODesc.InputLayout = { m_inputLayout.data(), (uint32_t)m_inputLayout.size() };
opaquePSODesc.pRootSignature = m_rootSignature.Get();
opaquePSODesc.VS =
{
    reinterpret_cast<BYTE*>(m_shaders["MainVS"]->GetBufferPointer()),
    m_shaders["MainVS"]->GetBufferSize()
};
opaquePSODesc.PS =
{
    reinterpret_cast<BYTE*>(m_shaders["MainPS"]->GetBufferPointer()),
    m_shaders["MainPS"]->GetBufferSize()
};
opaquePSODesc.RasterizerState = CD3DX12_RASTERIZER_DESC(D3D12_DEFAULT);
opaquePSODesc.BlendState = CD3DX12_BLEND_DESC(D3D12_DEFAULT);
opaquePSODesc.DepthStencilState = CD3DX12_DEPTH_STENCIL_DESC(D3D12_DEFAULT);
opaquePSODesc.SampleMask = UINT_MAX;  //set the sampling for each pixel(Multiple sampling takes up to 32 samples)
opaquePSODesc.PrimitiveTopologyType = D3D12_PRIMITIVE_TOPOLOGY_TYPE_TRIANGLE;
opaquePSODesc.NumRenderTargets = 1;   //The number of render target formats in the RTVFormats member
opaquePSODesc.RTVFormats[0] = DXGI_FORMAT_R8G8B8A8_UNORM;
opaquePSODesc.DSVFormat = DXGI_FORMAT_D24_UNORM_S8_UINT;
opaquePSODesc.SampleDesc.Count = 1;

ThrowIfFailed(m_device->CreateGraphicsPipelineState(&opaquePSODesc, IID_PPV_ARGS(&m_PSOs["opaque"])));

NAME_D3D12_OBJECT(m_PSOs["opaque"]);

// skybox PSO
D3D12_GRAPHICS_PIPELINE_STATE_DESC cubemapPSODesc = opaquePSODesc;
// forbide back culling 
cubemapPSODesc.RasterizerState.CullMode = D3D12_CULL_MODE_NONE;
// let cubemap z = 1 pass z-test, otherwise it'll be failed in z-test because data of zbuffer is 1
cubemapPSODesc.DepthStencilState.DepthFunc = D3D12_COMPARISON_FUNC_LESS_EQUAL;
cubemapPSODesc.pRootSignature = m_rootSignature.Get();
cubemapPSODesc.VS =
{
    reinterpret_cast<BYTE*>(m_shaders["CubemapVS"]->GetBufferPointer()),
    m_shaders["CubemapVS"]->GetBufferSize()
};
cubemapPSODesc.PS =
{
    reinterpret_cast<BYTE*>(m_shaders["CubemapPS"]->GetBufferPointer()),
    m_shaders["CubemapPS"]->GetBufferSize()
};

ThrowIfFailed(m_device->CreateGraphicsPipelineState(&cubemapPSODesc, IID_PPV_ARGS(&m_PSOs["cubemap"])));

NAME_D3D12_OBJECT(m_PSOs["cubemap"]);

shader

cbuffer ObjectCB : register(b0)
{
    float4x4 world;
}

cbuffer PassCB : register(b1)
{
    float4x4 view;
    float4x4 inverseView;
    float4x4 projection;
    float4x4 inverseProjection;
    float4x4 viewProjection;
    float4x4 inverseViewProjection;
    
    float3 eyeWorldPosition;

    Light lights[MAX_LIGHT_COUNT];
}

cbuffer MaterialCB : register(b2)
{
    int specualrShiness;
    float ambientAlbedo;
}

SamplerState g_SamperPointWrap : register(s0);
SamplerState g_SamperPointClamp : register(s1);
SamplerState g_SamperLinerWrap : register(s2);
SamplerState g_SamperLinerClamp : register(s3);
SamplerState g_SamperAnisotropyWrap : register(s4);
SamplerState g_SamperAnisotropyClamp : register(s5);

Texture2D g_diffuseTexture : register(t0, space0);
Texture2D g_specularTexture : register(t1, space0);
TextureCube g_cubemap : register(t2, space0);

struct VSInput
{
    float3 positionL : POSITION;
    float3 normalL : NORMAL;
    float2 uv : TEXCOORD;
};

struct PSInput
{
    float3 positionL : POSITION;
    float4 positionH : SV_POSITION;
};

// VS
PSInput main(VSInput input)
{
    PSInput output;
    
    // 用于立方体贴图采样的查找向量
    output.positionL = input.positionL;
    
    float4 positionW = mul(float4(output.positionL, 1.f), world);
    
    // 天空球始终以相机为中心
    positionW.xyz += eyeWorldPosition;
    
    //  Set z = w so that z/w = 1,使得立方体纹理始终位于远平面
    output.positionH = mul(positionW, viewProjection).xyww;
    
    return output;
}

// PS
float4 main(PSInput input) : SV_TARGET
{
    return g_cubemap.Sample(g_SamperLinerWrap, input.positionL);
}

输出

reference

Texassemble · microsoft/DirectXTex Wiki)

[Game-Programmer-Study-Notes/README.md at master · QianMo](https://github.com/QianMo/Game-Programmer-Study-Notes/blob/master/Content/《Real-Time Rendering 3rd》读书笔记/README.md)

标签：天空,pRenderer,实现,pSkybox,register,纹理,DX12,opaquePSODesc,D3D12
From： https://www.cnblogs.com/chenglixue/p/17374050.html

DX12 实现天空盒

前言

创建dds立方体贴图

语法

例子

要点

绘制天空盒

生成球体

加载立方体纹理

球体材质

draw call项

SRV

PSO

shader

输出

reference

相关文章

赞助商

阅读排行

DX12 实现 天空盒

前言

创建dds立方体贴图

语法

例子

要点

绘制天空盒

生成球体

加载立方体纹理

球体材质

draw call项

SRV

PSO

shader

输出

reference

相关文章

赞助商

阅读排行

DX12 实现天空盒