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direct3d

Creating Root Signature failed after changing version 1.1

I mimimized my code to the problem part. I used to create root signature version 1.0 with no problem. Then I tried to upgrade my code to compatible with root signature version 1.1 if the hardware support.

   D3D12_ROOT_DESCRIPTOR1 CBV1rootDescriptor;
   CBV1rootDescriptor.ShaderRegister = 0;
   CBV1rootDescriptor.RegisterSpace = 0;
   CBV1rootDescriptor.Flags = D3D12_ROOT_DESCRIPTOR_FLAG_NONE;

   D3D12_ROOT_DESCRIPTOR1 CBV2rootDescriptor;
   CBV2rootDescriptor.ShaderRegister = 1;
   CBV2rootDescriptor.RegisterSpace = 0;
   CBV1rootDescriptor.Flags = D3D12_ROOT_DESCRIPTOR_FLAG_NONE;

   D3D12_ROOT_PARAMETER1 rootParam[2];
   rootParam[0].ParameterType = D3D12_ROOT_PARAMETER_TYPE_CBV;
   rootParam[0].Descriptor = CBV1rootDescriptor;
   rootParam[0].ShaderVisibility = D3D12_SHADER_VISIBILITY_ALL;

   rootParam[1].ParameterType = D3D12_ROOT_PARAMETER_TYPE_CBV;
   rootParam[1].Descriptor = CBV2rootDescriptor;
   rootParam[1].ShaderVisibility = D3D12_SHADER_VISIBILITY_ALL;

   D3D12_FEATURE_DATA_ROOT_SIGNATURE featureData = {};
   featureData.HighestVersion = D3D_ROOT_SIGNATURE_VERSION_1_1;
   if (FAILED(device->CheckFeatureSupport(D3D12_FEATURE_ROOT_SIGNATURE, &featureData, sizeof(featureData))))
   {
       featureData.HighestVersion = D3D_ROOT_SIGNATURE_VERSION_1_0;
   }

   D3D12_ROOT_SIGNATURE_DESC1 rootSigDesc = {};
   rootSigDesc.NumParameters = _countof(rootParam);
   rootSigDesc.pParameters = rootParam;
   rootSigDesc.NumStaticSamplers = 0;
   rootSigDesc.pStaticSamplers = nullptr;
   rootSigDesc.Flags = D3D12_ROOT_SIGNATURE_FLAG_ALLOW_INPUT_ASSEMBLER_INPUT_LAYOUT;

   D3D12_VERSIONED_ROOT_SIGNATURE_DESC VersionedrootSigDesc = {};
   VersionedrootSigDesc.Version = featureData.HighestVersion;
   VersionedrootSigDesc.Desc_1_1 = rootSigDesc;

   ID3DBlob* serializedRootSig = nullptr;
   ID3DBlob* errorBlob = nullptr;

   ThrowIfFailed(D3DX12SerializeVersionedRootSignature(&VersionedrootSigDesc, featureData.HighestVersion, &serializedRootSig, &errorBlob));

The code will throw if I run like above, I checked featureData.HighestVersion is 1.1. If I forced featureData.HighestVersion to 1.0, the code will pass. And if I remove the second rootParam[1], only use 1 rootParam, even featureData.HighestVersion is 1.1, the code will pass. Does version 1.1 has some restrictions on CBV on root descriptor? (Windows 10 21H2 OS Build 19044.1706, Visual Studio 2022 community 17.2.2)

Solution 
  • D3D12_ROOT_DESCRIPTOR1 CBV2rootDescriptor;
CBV2rootDescriptor.ShaderRegister = 1;
CBV2rootDescriptor.RegisterSpace = 0;
CBV1rootDescriptor.Flags = D3D12_ROOT_DESCRIPTOR_FLAG_NONE;

    Since I copied and pasted for CBV2, I didn't change CBV1rootDescriptor.Flags = D3D12_ROOT_DESCRIPTOR_FLAG_NONE; to CBV2rootDescriptor.Flags = D3D12_ROOT_DESCRIPTOR_FLAG_NONE; and I didn't initialize CBV2rootDescriptor, so CBV2rootDescriptor.Flags could be random number which cause the creation failed. I found this when I initialize CBV2rootDescriptor to {}, then the failure gone, which made to to look at each assignment again and found CBV1rootDescriptor.Flags didn't change to CBV2rootDescriptor.Flags.