I recently got the idea to try to create a procedural shader system for DirectX 11. This basically entails that one simply throws a mesh at the shader generator and it generates a customized shader for this mesh that suits it perfectly.
I knew it is being done in high-end game engines but I had no idea how one actually does it. I spent quite a lot of time on google trying to find this, but it basically looks like some universal secret even though it actually is quite simple. So I played around with it a bit and I managed to get it to work in the end. So the follow code snippet is the procedure I used for getting it to work, probably a whole load of other ones out there.
Just hope this saves other people the same frustrations I had for a while.
void GenerateShader()
{
ostringstream shader;
// Basic Vertex Shader
shader << "float4 BasicVS( float4 Pos : POSITION ) : SV_POSITION" << endl;
shader << "{" << endl;
shader << " return Pos;" << endl;
shader << "}" << endl;
// Basic Pixel Shader
shader << "float4 BasicPS( float4 Pos : SV_POSITION ) : SV_Target" << endl;
shader <<"{" << endl;
shader <<" return float4( 1.0f, 1.0f, 1.0f, 1.0f );" << endl;
shader <<"}" << endl;
// A standard DirectX 10 technique
shader << "technique10 DefaultTechnique" << endl;
shader << "{" << endl;
shader << " pass p0" << endl;
shader << " {" << endl;
shader << " SetGeometryShader(NULL);" << endl;
shader << " SetVertexShader(CompileShader(vs_4_0, BasicVS()));" << endl;
shader << " SetPixelShader(CompileShader(ps_4_0, BasicPS()));" << endl;
shader << " }" << endl;
shader << "}" << endl;
// This is where the "magic" is at. Grab the char* from your stringstream
// and feed it into D3DCompile() along with whatever other parameters you usually send it.
ID3DBlob* errorBlob;
unsigned int shaderSize = shader.str().size() * sizeof(char);
HRESULT hr = D3DCompile(shader.str().c_str(), shaderSize, "none", 0, 0, "DefaultTechnique",
"fx_4_0", D3D10_SHADER_ENABLE_STRICTNESS, 0, &blob_, &errorBlob);
if( FAILED(hr) )
{
OutputDebugStringA( (char*)errorBlob->GetBufferPointer() );
}
SAFE_RELEASE( errorBlob );
}
So now all that is left is 99.9% of the work to actually switch case together a shader that supports all the things your different meshes might need.
Maybe I will post something on that later when I manage to make a dent in that daunting task :p
