Shader: Fix function calls with OpenGL

include/Nazara/Shader/GlslWriter.hpp

@@ -102,6 +102,7 @@ namespace Nz
 			void Visit(ShaderAst::CallFunctionExpression& node) override;
 			void Visit(ShaderAst::CastExpression& node) override;
 			void Visit(ShaderAst::ConstantValueExpression& node) override;
+			void Visit(ShaderAst::FunctionExpression& node) override;
 			void Visit(ShaderAst::IntrinsicExpression& node) override;
 			void Visit(ShaderAst::SwizzleExpression& node) override;
 			void Visit(ShaderAst::VariableValueExpression& node) override;

include/Nazara/Shader/LangWriter.hpp

@@ -113,6 +113,7 @@ namespace Nz
 			void Visit(ShaderAst::ConditionalExpression& node) override;
 			void Visit(ShaderAst::ConstantValueExpression& node) override;
 			void Visit(ShaderAst::ConstantExpression& node) override;
+			void Visit(ShaderAst::FunctionExpression& node) override;
 			void Visit(ShaderAst::IdentifierExpression& node) override;
 			void Visit(ShaderAst::IntrinsicExpression& node) override;
 			void Visit(ShaderAst::StructTypeExpression& node) override;

src/Nazara/Shader/GlslWriter.cpp

@@ -967,7 +967,12 @@ namespace Nz
 				static_assert(AlwaysFalse<T>::value, "non-exhaustive visitor");
 		}, node.value);
 	}
-	
+
+	void GlslWriter::Visit(ShaderAst::FunctionExpression& node)
+	{
+		const std::string& targetName = Retrieve(m_currentState->previsitor.functions, node.funcId).name;
+		Append(targetName);
+	}
 	
 	void GlslWriter::Visit(ShaderAst::IntrinsicExpression& node)
 	{

src/Nazara/Shader/LangWriter.cpp

@@ -969,6 +969,11 @@ namespace Nz
 		AppendIdentifier(m_currentState->constants, node.constantId);
 	}
 
+	void LangWriter::Visit(ShaderAst::FunctionExpression& node)
+	{
+		Append(Retrieve(m_currentState->functions, node.funcId).name);
+	}
+
 	void LangWriter::Visit(ShaderAst::IdentifierExpression& node)
 	{
 		Append(node.identifier);

tests/Engine/Shader/FunctionsTests.cpp

@@ -0,0 +1,91 @@
+#include <Engine/Shader/ShaderUtils.hpp>
+#include <Nazara/Core/File.hpp>
+#include <Nazara/Core/StringExt.hpp>
+#include <Nazara/Shader/ShaderBuilder.hpp>
+#include <Nazara/Shader/ShaderLangParser.hpp>
+#include <catch2/catch.hpp>
+#include <cctype>
+
+TEST_CASE("functions", "[Shader]")
+{
+	SECTION("Simple function call")
+	{
+		std::string_view nzslSource = R"(
+[nzsl_version("1.0")]
+module;
+
+struct FragOut
+{
+	[location(0)] value: f32
+}
+
+fn GetValue() -> f32
+{
+	return 42.0;
+}
+
+[entry(frag)]
+fn main() -> FragOut
+{
+	let output: FragOut;
+	output.value = GetValue();
+
+	return output;
+}
+)";
+
+		Nz::ShaderAst::ModulePtr shaderModule = Nz::ShaderLang::Parse(nzslSource);
+		shaderModule = SanitizeModule(*shaderModule);
+
+		ExpectGLSL(*shaderModule, R"(
+float GetValue()
+{
+	return 42.000000;
+}
+
+/*************** Outputs ***************/
+layout(location = 0) out float _NzOut_value;
+
+void main()
+{
+	FragOut output_;
+	output_.value = GetValue();
+	
+	_NzOut_value = output_.value;
+	return;
+}
+)");
+
+		ExpectNZSL(*shaderModule, R"(
+fn GetValue() -> f32
+{
+	return 42.000000;
+}
+
+[entry(frag)]
+fn main() -> FragOut
+{
+	let output: FragOut;
+	output.value = GetValue();
+	return output;
+}
+)");
+
+		ExpectSPIRV(*shaderModule, R"(
+OpFunction
+OpLabel
+OpReturnValue
+OpFunctionEnd
+OpFunction
+OpLabel
+OpVariable
+OpFunctionCall
+OpAccessChain
+OpStore
+OpLoad
+OpCompositeExtract
+OpStore
+OpReturn
+OpFunctionEnd)");
+	}
+}