Shader: Add support for max/min intrinsic

include/Nazara/Shader/Ast/Enums.hpp

@@ -57,6 +57,8 @@ namespace Nz::ShaderAst
 		CrossProduct = 0,
 		DotProduct = 1,
 		Length = 3,
+		Max = 4,
+		Min = 5,
 		SampleTexture = 2,
 	};
 

src/Nazara/Shader/Ast/SanitizeVisitor.cpp

@@ -448,6 +448,8 @@ namespace Nz::ShaderAst
 		{
 			case IntrinsicType::CrossProduct:
 			case IntrinsicType::DotProduct:
+			case IntrinsicType::Max:
+			case IntrinsicType::Min:
 			{
 				if (clone->parameters.size() != 2)
 					throw AstError { "Expected two parameters" };
@@ -523,6 +525,21 @@ namespace Nz::ShaderAst
 				break;
 			}
 
+			case IntrinsicType::Max:
+			case IntrinsicType::Min:
+			{
+				const ExpressionType& type = GetExpressionType(*clone->parameters.front());
+				if (!IsPrimitiveType(type) && !IsVectorType(type))
+					throw AstError{ "max and min only work with primitive and vector types" };
+
+				if ((IsPrimitiveType(type) && std::get<PrimitiveType>(type) == PrimitiveType::Boolean) ||
+				    (IsVectorType(type) && std::get<VectorType>(type).type == PrimitiveType::Boolean))
+					throw AstError{ "max and min do not work with booleans" };
+
+				clone->cachedExpressionType = type;
+				break;
+			}
+
 			case IntrinsicType::SampleTexture:
 			{
 				clone->cachedExpressionType = VectorType{ 4, std::get<SamplerType>(GetExpressionType(*clone->parameters.front())).sampledType };

src/Nazara/Shader/GlslWriter.cpp

@@ -822,6 +822,14 @@ namespace Nz
 				Append("length");
 				break;
 
+			case ShaderAst::IntrinsicType::Max:
+				Append("max");
+				break;
+
+			case ShaderAst::IntrinsicType::Min:
+				Append("min");
+				break;
+
 			case ShaderAst::IntrinsicType::SampleTexture:
 				Append("texture");
 				break;

src/Nazara/Shader/LangWriter.cpp

@@ -658,6 +658,14 @@ namespace Nz
 				Append("length");
 				break;
 
+			case ShaderAst::IntrinsicType::Max:
+				Append("max");
+				break;
+
+			case ShaderAst::IntrinsicType::Min:
+				Append("min");
+				break;
+
 			case ShaderAst::IntrinsicType::SampleTexture:
 				Append("texture");
 				break;

src/Nazara/Shader/ShaderLangParser.cpp

@@ -22,6 +22,8 @@ namespace Nz::ShaderLang
 		std::unordered_map<std::string, ShaderAst::IntrinsicType> s_identifierToIntrinsic = {
 			{ "cross", ShaderAst::IntrinsicType::CrossProduct },
 			{ "dot", ShaderAst::IntrinsicType::DotProduct },
+			{ "max", ShaderAst::IntrinsicType::Max },
+			{ "min", ShaderAst::IntrinsicType::Min },
 			{ "length", ShaderAst::IntrinsicType::Length },
 		};
 

src/Nazara/Shader/SpirvAstVisitor.cpp

@@ -710,6 +710,51 @@ namespace Nz
 				break;
 			}
 
+			case ShaderAst::IntrinsicType::Max:
+			case ShaderAst::IntrinsicType::Min:
+			{
+				UInt32 glslInstructionSet = m_writer.GetExtendedInstructionSet("GLSL.std.450");
+
+				const ShaderAst::ExpressionType& parameterType = GetExpressionType(*node.parameters[0]);
+				assert(IsPrimitiveType(parameterType) || IsVectorType(parameterType));
+				UInt32 typeId = m_writer.GetTypeId(parameterType);
+
+				ShaderAst::PrimitiveType basicType;
+				if (IsPrimitiveType(parameterType))
+					basicType = std::get<ShaderAst::PrimitiveType>(parameterType);
+				else if (IsVectorType(parameterType))
+					basicType = std::get<ShaderAst::VectorType>(parameterType).type;
+				else
+					throw std::runtime_error("unexpected expression type");
+
+				GLSLstd450 op;
+				switch (basicType)
+				{
+					case ShaderAst::PrimitiveType::Boolean:
+						throw std::runtime_error("unexpected boolean for max/min intrinsic");
+
+					case ShaderAst::PrimitiveType::Float32:
+						op = (node.intrinsic == ShaderAst::IntrinsicType::Max) ? GLSLstd450FMax : GLSLstd450FMin;
+						break;
+
+					case ShaderAst::PrimitiveType::Int32:
+						op = (node.intrinsic == ShaderAst::IntrinsicType::Max) ? GLSLstd450SMax : GLSLstd450SMin;
+						break;
+
+					case ShaderAst::PrimitiveType::UInt32:
+						op = (node.intrinsic == ShaderAst::IntrinsicType::Max) ? GLSLstd450UMax : GLSLstd450UMin;
+						break;
+				}
+
+				UInt32 firstParam = EvaluateExpression(node.parameters[0]);
+				UInt32 secondParam = EvaluateExpression(node.parameters[1]);
+				UInt32 resultId = m_writer.AllocateResultId();
+
+				m_currentBlock->Append(SpirvOp::OpExtInst, typeId, resultId, glslInstructionSet, op, firstParam, secondParam);
+				PushResultId(resultId);
+				break;
+			}
+
 			case ShaderAst::IntrinsicType::SampleTexture:
 			{
 				UInt32 typeId = m_writer.GetTypeId(ShaderAst::VectorType{4, ShaderAst::PrimitiveType::Float32});

src/Nazara/Shader/SpirvWriter.cpp

@@ -283,6 +283,8 @@ namespace Nz
 						// Require GLSL.std.450
 						case ShaderAst::IntrinsicType::CrossProduct:
 						case ShaderAst::IntrinsicType::Length:
+						case ShaderAst::IntrinsicType::Max:
+						case ShaderAst::IntrinsicType::Min:
 							extInsts.emplace("GLSL.std.450");
 							break;