Function GatherSystemFields

shadercompiler/EffectCompilerMetal.cpp:2254–2313

}

void GatherSystemFields( ASTNode* destStruct, std::vector<ASTNode*>& accessors, std::vector<ASTNode*>& argumentAccessors, ASTNode* accessParent, ASTNode* sourceStruct, ASTNode* shaderBody, ParserState& state )
{
	for( auto member : sourceStruct->GetChildren() )
	{
		if( member->GetType().IsStruct() )
		{
			for( auto name : member->GetChildren() )
			{
				GatherSystemFields( destStruct, accessors, argumentAccessors, NewDot( state, accessParent->Copy(), name->GetSymbol() ), name->GetType().symbol->definition, shaderBody, state );
			}
		}
		else
		{
			for( auto name : member->GetChildren() )
			{
				auto it = s_systemSemantics.find( name->GetSymbol()->semantic );
				if( it != s_systemSemantics.end() )
				{
					auto param = NewFunctionParameter( state, name->GetType() );
					param->GetSymbol()->registerSpecifier[{}] = MetalSystemSemantics( it->second );
					destStruct->AddChild( param );
					argumentAccessors.push_back( NewVarIdentifier( state, param->GetSymbol() ) );
					accessors.push_back( NewDot( state, accessParent->Copy(), name->GetSymbol() ) );

					// subtract base_vertex from vertex_id to match dx12 behaviour for SV_VertexID
					if( name->GetSymbol()->semantic == "SV_VertexID" )
					{
						auto base_param = NewFunctionParameter( state, hlsl::uint_t );
						base_param->GetSymbol()->registerSpecifier[{}] = MetalSystemSemantics( MetalSystemSemanticsType::Enum::base_vertex );
						destStruct->AddChild( base_param );

						auto assignment = NewBinaryExpression(
							state,
							OP_SUB_ASSIGN,
							NewVarIdentifier( state, param->GetSymbol() ),
							NewVarIdentifier( state, base_param->GetSymbol() ) );
						ASTNode* node = NewExpressionStatement( state, assignment );
						shaderBody->AddChild( node );
					}

					// subtract base_instance from instance_id to match dx12 behaviour for SV_InstanceID
					if( name->GetSymbol()->semantic == "SV_InstanceID" )
					{
						auto base_param = NewFunctionParameter( state, hlsl::uint_t );
						base_param->GetSymbol()->registerSpecifier[{}] = MetalSystemSemantics( MetalSystemSemanticsType::Enum::base_instance );
						destStruct->AddChild( base_param );

						auto assignment = NewBinaryExpression(
							state,
							OP_SUB_ASSIGN,
							NewVarIdentifier( state, param->GetSymbol() ),
							NewVarIdentifier( state, base_param->GetSymbol() ) );
						ASTNode* node = NewExpressionStatement( state, assignment );
						shaderBody->AddChild( node );
					}
				}
			}
		}