Shader Model 6

Shader Model 6 is the latest HLSL compiler technology. It is required for DirectX Raytracing, DirectML, DirectX Mesh & Amplification Shaders, and a number of other DirectX 12 features. The DXIL compiler (DXC ) generates Shader Model 6 programs, and the compiler is based on LLVM and is hosted on GitHub. A prebuilt version of DXC.EXE is provided in the Windows 10 SDK (17134 or later).

DirectX 11 does not support Shader Model 6 shaders.

Checking for Shader Model 6 support level

While most modern DirectX 12 drivers support Shader Model 6, you need to verify the level of support required by your program.

D3D12_FEATURE_DATA_SHADER_MODEL shaderModel = { D3D_SHADER_MODEL_6_0 };

if (FAILED(device->CheckFeatureSupport(D3D12_FEATURE_SHADER_MODEL, &shaderModel, sizeof(shaderModel))))
{
#ifdef _DEBUG
    OutputDebugStringA("ERROR: Shader Model 6.0 is not supported!\n");
#endif
    throw std::exception("Shader Model 6.0 is not supported!");
}

For higher shader models, you may be running on a system that doesn't recognize them, so the logic is slightly more complex in this case. This code finds the highest possible supported level, which is overkill in most cases, but is a useful reference:

D3D12_FEATURE_DATA_SHADER_MODEL shaderModel = {};

#if defined(NTDDI_WIN10_VB) && (NTDDI_VERSION >= NTDDI_WIN10_VB)
shaderModel.HighestShaderModel = D3D_SHADER_MODEL_6_6;
#elif defined(NTDDI_WIN10_19H1) && (NTDDI_VERSION >= NTDDI_WIN10_19H1)
shaderModel.HighestShaderModel = D3D_SHADER_MODEL_6_5;
#elif defined(NTDDI_WIN10_RS5) && (NTDDI_VERSION >= NTDDI_WIN10_RS5)
shaderModel.HighestShaderModel = D3D_SHADER_MODEL_6_4;
#elif defined(NTDDI_WIN10_RS4) && (NTDDI_VERSION >= NTDDI_WIN10_RS4)
shaderModel.HighestShaderModel = D3D_SHADER_MODEL_6_2;
#elif defined(NTDDI_WIN10_RS3) && (NTDDI_VERSION >= NTDDI_WIN10_RS3)
shaderModel.HighestShaderModel = D3D_SHADER_MODEL_6_1;
#else
shaderModel.HighestShaderModel = D3D_SHADER_MODEL_6_0;
#endif

HRESULT hr = device->CheckFeatureSupport(D3D12_FEATURE_SHADER_MODEL, &shaderModel, sizeof(shaderModel));
while (hr == E_INVALIDARG && shaderModel.HighestShaderModel > D3D_SHADER_MODEL_6_0)
{
    shaderModel.HighestShaderModel = static_cast<D3D_SHADER_MODEL>(static_cast<int>(shaderModel.HighestShaderModel) - 1);
    hr = device->CheckFeatureSupport(D3D12_FEATURE_SHADER_MODEL, &shaderModel, sizeof(shaderModel));
}

if (FAILED(hr))
{
    shaderModel.HighestShaderModel = D3D_SHADER_MODEL_5_1;
}

Note that a number of Shader Model levels were defined originally as 'experimental' so were not supported by the released DXC compiler or production drivers until later releases of Windows.

Using Shader Model 6 shaders for DirectX Tool Kit

By default shaders are built with FXC for Shader Model 5.1 (using Root Signature 1.1). To use Shader Model 6, invoke the CompileScripts.cmd with dxil:

CompileShaders dxil

Be sure your application verifies that Shader Model 6 is supported before using the DirectX Tool Kit effects, SpriteBatch, or any other shader-using class or you will get runtime errors/C++ exceptions that may be harder to diagnose.

If you wish to modify the Visual Studio vcxproj that invokes the shader build to use DXIL, modify the Exec statement near the bottom of the file as follows:

<Target Name="ATGEnsureShaders" BeforeTargets="PrepareForBuild">
    <Exec Condition="!Exists('src/Shaders/Compiled/SpriteEffect_SpriteVertexShader.inc')"
          WorkingDirectory="$(ProjectDir)src/Shaders"
          Command="CompileShaders dxil" 
          EnvironmentVariables="WindowsSdkVerBinPath=$(WDKBinRoot)" />
</Target>

Visual Studio HLSL integration

UNDER CONSTRUCTION

Further reading

Microsoft Docs: Shader Model 6

Announcing Microsoft DirectX Raytracing! (requires Shader Model 6.3 or later)

Direct Machine Learning (DirectML) (requires Shader Model 6.4 or later)

Mesh Shaders and Amplification Shaders: Reinventing the Geometry Pipeline (requires Shader Model 6.5 or later)