DX12

CD3DX12_DESCRIPTOR_RANGE1

的baseShaderRegister

用来指定 t0 t1 b0 b1...的index 

t0 srv

b0 constant buffer

u0 uav

这个的名字叫 hlsl bind slot

还有个index 叫 API bind slot 

pCmdList->SetComputeRoot32BitConstant(0,seed); // 0 is the parameter index,--api bind slot

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Descriptor GPU资源的描述信息

Descriptor Heaps 

Descriptor Tables

可以快速申请，因为只是标记（memory 地址）

CD3DX12_DESCRIPTOR_RANGE1 DescRange[6]; DescRange[0].Init(D3D12_DESCRIPTOR_RANGE_SRV,6,2); // t2-t7

DescRange[1].Init(D3D12_DESCRIPTOR_RANGE_UAV,4,0); // u0-u3

DescRange[2].Init(D3D12_DESCRIPTOR_RANGE_SAMPLER,2,0); // s0-s1

CD3DX12_ROOT_PARAMETER1 RP[7]; RP[0].InitAsConstants(3,2); // 3 constants at b2

RP[1].InitAsDescriptorTable(2,&DescRange[0]); // 2 ranges t2-t7 and u0-u3

CD3DX12_STATIC_SAMPLER StaticSamplers[1];

StaticSamplers[0].Init(3, D3D12_FILTER_ANISOTROPIC); // s3

CD3DX12_STATIC_SAMPLER StaticSamplers[1];

StaticSamplers[0].Init(3, D3D12_FILTER_ANISOTROPIC); // s3

CD3DX12_VERSIONED_ROOT_SIGNATURE_DESC RootSig(7,RP,1,StaticSamplers);

ID3DBlob* pSerializedRootSig;

CheckHR(D3D12SerializeVersionedRootSignature(&RootSig,pSerializedRootSig));

ID3D12RootSignature* pRootSignature;

hr = CheckHR(pDevice->CreateRootSignature( pSerializedRootSig->GetBufferPointer(),pSerializedRootSig->GetBufferSize(), __uuidof(ID3D12RootSignature), &pRootSignature));

Root Signaatures 包含 root constants, root descriptors,   descriptor tables 三种类型

是shader paramaters

REF:

https://docs.microsoft.com/en-us/windows/desktop/direct3d12/descriptor-tables-overview

https://docs.microsoft.com/en-us/windows/desktop/direct3d12/creating-a-root-signature

https://www.3dgep.com/learning-directx-12-3/

https://docs.microsoft.com/en-us/windows/win32/direct3d12/descriptors

https://docs.microsoft.com/en-us/windows/win32/direct3d12/descriptors-overview

descriptors包含srv uav cbv sampler等资源

bind的时候是用descriptor来bind的

这东西就相当于metal的 argument buffer/argument table

https://docs.microsoft.com/en-us/windows/win32/direct3d12/copying-descriptors

descriptor copy是一个走cpu timeline的操作

但source不能对gpu可见 dest可以对cpu gpu都可见

所以cpu copy descriptor的时候 要等gpu把这些资源用完

https://docs.microsoft.com/en-us/windows/win32/direct3d12/resource-binding-flow-of-control

resource类型

• Constant buffer view (CBV)
• Unordered access view (UAV)
• Shader resource view (SRV)
• Samplers
• Render Target View (RTV)
• Depth Stencil View (DSV)
• Index Buffer View (IBV)
• Vertex Buffer View (VBV)
• Stream Output View (SOV)