From e7a25732210755ad0f4aaa1db69b25f90ae6bb36 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=A9r=C3=B4me=20Leclercq?= <lynix680@gmail.com>
Date: Wed, 26 May 2021 22:17:07 +0200
Subject: [PATCH] Shader: Add support for FragCoord builtin

---
 include/Nazara/Shader/Ast/Enums.hpp    | 3 ++-
 src/Nazara/Shader/GlslWriter.cpp       | 5 +++++
 src/Nazara/Shader/LangWriter.cpp       | 4 ++++
 src/Nazara/Shader/ShaderLangParser.cpp | 1 +
 src/Nazara/Shader/SpirvWriter.cpp      | 3 ++-
 5 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/include/Nazara/Shader/Ast/Enums.hpp b/include/Nazara/Shader/Ast/Enums.hpp
index d87aae0b0..4717c2ab9 100644
--- a/include/Nazara/Shader/Ast/Enums.hpp
+++ b/include/Nazara/Shader/Ast/Enums.hpp
@@ -43,7 +43,8 @@ namespace Nz::ShaderAst
 
 	enum class BuiltinEntry
 	{
-		VertexPosition, // gl_Position
+		FragCoord      = 1, // gl_FragCoord
+		VertexPosition = 0, // gl_Position
 	};
 
 	enum class ExpressionCategory
diff --git a/src/Nazara/Shader/GlslWriter.cpp b/src/Nazara/Shader/GlslWriter.cpp
index 004bbc7da..f93f1c216 100644
--- a/src/Nazara/Shader/GlslWriter.cpp
+++ b/src/Nazara/Shader/GlslWriter.cpp
@@ -85,6 +85,7 @@ namespace Nz
 		};
 
 		std::unordered_map<ShaderAst::BuiltinEntry, Builtin> s_builtinMapping = {
+			{ ShaderAst::BuiltinEntry::FragCoord,      { "gl_FragCoord", ShaderStageType::Fragment } },
 			{ ShaderAst::BuiltinEntry::VertexPosition, { "gl_Position", ShaderStageType::Vertex } }
 		};
 	}
@@ -191,6 +192,10 @@ namespace Nz
 	{
 		switch (builtin)
 		{
+			case ShaderAst::BuiltinEntry::FragCoord:
+				Append("gl_FragCoord");
+				break;
+
 			case ShaderAst::BuiltinEntry::VertexPosition:
 				Append("gl_Position");
 				break;
diff --git a/src/Nazara/Shader/LangWriter.cpp b/src/Nazara/Shader/LangWriter.cpp
index ebaae6ea7..0d0b8c237 100644
--- a/src/Nazara/Shader/LangWriter.cpp
+++ b/src/Nazara/Shader/LangWriter.cpp
@@ -231,6 +231,10 @@ namespace Nz
 
 		switch (*builtin.builtin)
 		{
+			case ShaderAst::BuiltinEntry::FragCoord:
+				Append("builtin(fragcoord)");
+				break;
+
 			case ShaderAst::BuiltinEntry::VertexPosition:
 				Append("builtin(position)");
 				break;
diff --git a/src/Nazara/Shader/ShaderLangParser.cpp b/src/Nazara/Shader/ShaderLangParser.cpp
index fc09a3a13..8531a8d5a 100644
--- a/src/Nazara/Shader/ShaderLangParser.cpp
+++ b/src/Nazara/Shader/ShaderLangParser.cpp
@@ -34,6 +34,7 @@ namespace Nz::ShaderLang
 		};
 
 		std::unordered_map<std::string, ShaderAst::BuiltinEntry> s_builtinMapping = {
+			{ "fragcoord", ShaderAst::BuiltinEntry::FragCoord },
 			{ "position", ShaderAst::BuiltinEntry::VertexPosition }
 		};
 
diff --git a/src/Nazara/Shader/SpirvWriter.cpp b/src/Nazara/Shader/SpirvWriter.cpp
index d9b2da928..4406719d5 100644
--- a/src/Nazara/Shader/SpirvWriter.cpp
+++ b/src/Nazara/Shader/SpirvWriter.cpp
@@ -36,7 +36,8 @@ namespace Nz
 		};
 
 		std::unordered_map<ShaderAst::BuiltinEntry, Builtin> s_builtinMapping = {
-			{ ShaderAst::BuiltinEntry::VertexPosition, { "VertexPosition", ShaderStageType::Vertex, SpirvBuiltIn::Position } }
+			{ ShaderAst::BuiltinEntry::FragCoord,      { "FragmentCoordinates", ShaderStageType::Fragment, SpirvBuiltIn::FragCoord } },
+			{ ShaderAst::BuiltinEntry::VertexPosition, { "VertexPosition", ShaderStageType::Vertex,   SpirvBuiltIn::Position } }
 		};
 
 		class PreVisitor : public ShaderAst::AstRecursiveVisitor