DXR

https://github.com/ConfettiFX/The-Forge/blob/master/CommonRaytracing_3/ThirdParty/DXR/doc/D3D12%20Raytracing%20Functional%20Spec.docx

dxr的spec 好难找

D3D12 Raytracing Functional Spec

https://github.com/NVIDIAGameWorks/Falcor/releases

https://github.com/Microsoft/DirectX-Graphics-Samples/blob/master/Samples/Desktop/D3D12Raytracing/readme.md

https://github.com/Microsoft/DirectX-Graphics-Samples/blob/master/Libraries/D3D12RaytracingFallback/readme.md

http://forums.directxtech.com/index.php?topic=5860.0

初始化拿到device 对rtx开一些特殊设置

fallback是个模拟rtx的库 api和硬件的rtx不太一样要专门写

初始化各种资源 初始化rtx专有资源

pso

as

加速结构 top bottom

top是对bottom的一个transform 数据本身在bottom

可以有一组bottome 每个里面又可以有很多geometry

语法参见        bottomLevelBuildDesc.NumDescs = static_cast<UINT>(geometryDescs.size());

它公用dx12的cmd自己再这个cmd上面建一个rtx的cmd

有五种shader可以写

hit 里面的光照是 光线打到的物体上的光照 比如反射 了abc 是abc物体的光照 而不是反射平面本身的材质光照

从传统光栅化shader到这种hit的光照shader的转换

vs部分的pos normal uv之类的 从hit的结果能拿到

只port ps光照部分即可 返回光照结果

几天没见pix长进了

https://blogs.msdn.microsoft.com/pix/gpu-captures/

看上去不错

https://blogs.msdn.microsoft.com/pix/2018/07/24/pix-1807-19-shader-table-viewer/

dx12和dxr都可以debug 需要把dxr的dll copy到pix.exe的位置

gpu hang的debug

https://blogs.msdn.microsoft.com/pix/tdr-debugging/

https://docs.microsoft.com/zh-cn/windows/desktop/direct3d12/using-d3d12-debug-layer-gpu-based-validation

https://blogs.msdn.microsoft.com/pix/programmatic-capture/

很强大

https://blogs.msdn.microsoft.com/pix/remoting/

远程连接

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

dx12 rootsignature  ---SRV CBV UAV 初始到各个slot

m_device->CreateConstantBufferView(&cbvDesc, m_cbvHeap->GetCPUDescriptorHandleForHeapStart()); 用这句连

CB--View --descriptorHeap

init 的时候把这些连上

render的时候 用这种方式更新 m_commandList->SetGraphicsRootDescriptorTable(0, m_cbvHeap->GetGPUDescriptorHandleForHeapStart()); 用heap更新slot

update更新了cb本身

dxr里面有shadertable 是upload buffer--committed resource

一条layout是一个shader rootsig mat等等

auto DispatchRays = [&](auto* commandList, auto* stateObject, auto* dispatchDesc)
{
dispatchDesc->HitGroupTable.StartAddress = m_hitGroupShaderTable->GetGPUVirtualAddress();
dispatchDesc->HitGroupTable.SizeInBytes = m_hitGroupShaderTable->GetDesc().Width;
dispatchDesc->HitGroupTable.StrideInBytes = m_hitGroupShaderTableStrideInBytes;
dispatchDesc->MissShaderTable.StartAddress = m_missShaderTable->GetGPUVirtualAddress();
dispatchDesc->MissShaderTable.SizeInBytes = m_missShaderTable->GetDesc().Width;
dispatchDesc->MissShaderTable.StrideInBytes = m_missShaderTableStrideInBytes;
dispatchDesc->RayGenerationShaderRecord.StartAddress = m_rayGenShaderTable->GetGPUVirtualAddress();
dispatchDesc->RayGenerationShaderRecord.SizeInBytes = m_rayGenShaderTable->GetDesc().Width;
dispatchDesc->Width = m_width;
dispatchDesc->Height = m_height;
commandList->DispatchRays(stateObject, dispatchDesc);
};

DispatchRays 可以把三种shader的起始地址连上

cbv之类的更新同dx12

namespace RootSignatureSlots = LocalRootSignature::AABB::Slot;
CD3DX12_ROOT_PARAMETER rootParameters[RootSignatureSlots::Count];
rootParameters[RootSignatureSlots::MaterialConstant].InitAsConstants(SizeOfInUint32(PrimitiveConstantBuffer), 1);
rootParameters[RootSignatureSlots::GeometryIndex].InitAsConstants(SizeOfInUint32(PrimitiveInstanceConstantBuffer), 2);

ThrowIfFailed(D3D12SerializeRootSignature(&desc, D3D_ROOT_SIGNATURE_VERSION_1, &blob, &error), error ? static_cast<wchar_t*>(error->GetBufferPointer()) : nullptr);
ThrowIfFailed(device->CreateRootSignature(1, blob->GetBufferPointer(), blob->GetBufferSize(), IID_PPV_ARGS(&(*rootSig))));

建立的时候 每条shaderrecord里面matID是不一样的 在hitshader里面

uint materialID = MaterialID;
uint triangleID = PrimitiveIndex();

RayTraceMeshInfo info = g_meshInfo[materialID];

const uint3 ii = Load3x16BitIndices(info.m_indexOffsetBytes + PrimitiveIndex() * 3 * 2);
const float2 uv0 = GetUVAttribute(info.m_uvAttributeOffsetBytes + ii.x * info.m_attributeStrideBytes);
const float2 uv1 = GetUVAttribute(info.m_uvAttributeOffsetBytes + ii.y * info.m_attributeStrideBytes);
const float2 uv2 = GetUVAttribute(info.m_uvAttributeOffsetBytes + ii.z * info.m_attributeStrideBytes);

就可以用这种方式matID拿到具体数据

==================

hit之后的顶点信息有两种方式可以获取 gloable /local sig

gloable的方式 需要传matID每次用这个ID从大的buffer（vb包含所有mesh）作为偏移拿到具体 pos uv normal tangent信息

另一种local的方式 每个hit shader传 自己的vb数据（initialze的时候每块mesh来处理 生成不同的 shader和vb）作为cb传入 用hit时的primitiveIndex拿到相应数据

这样hit的mat也都是每块mesh不一样的了

==========

这是些intric val

Values \ shaders

Ray dispatch system values:

uint2 DispatchRaysIndex()

uint2 DispatchRaysDimensions()

Ray system values:

float3 WorldRayOrigin()

float3 WorldRayDirection()

float RayTMin()

float RayTCurrent()

uint RayFlags()

Primitive/object space system values:

uint InstanceIndex()

uint InstanceID()

uint PrimitiveIndex()

float3 ObjectRayOrigin()

float3 ObjectRayDirection()

float3x4 ObjectToWorld()

float3x4 WorldToObject()

Hit specific system values:

uint HitKind()

=========================

draw() rastization

dispatch() compute

dispatchRays() raytracing

invoke