From ff072e148afae24018696c03a413c9ae2da6c929 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Tue, 14 Nov 2017 10:53:47 +0200
Subject: [PATCH] Basic OpenGL ES support in ProgramCompiler

Check language features against the correct version depending on the API
and emit a default precision qualifier for float types.
---
 source/programcompiler.cpp | 69 +++++++++++++++++++++++++++++++++-----
 source/programcompiler.h   |  7 +++-
 2 files changed, 67 insertions(+), 9 deletions(-)

diff --git a/source/programcompiler.cpp b/source/programcompiler.cpp
index fd27839d..6b8eb6e6 100644
--- a/source/programcompiler.cpp
+++ b/source/programcompiler.cpp
@@ -228,9 +228,23 @@ ProgramCompiler::Formatter::Formatter():
 
 void ProgramCompiler::Formatter::apply(ProgramSyntax::Stage &s)
 {
+	GLApi api = get_gl_api();
 	const Version &ver = s.required_version;
+
 	if(ver.major)
-		formatted += format("#version %d%d\n", ver.major, ver.minor);
+	{
+		formatted += format("#version %d%d", ver.major, ver.minor);
+		if(api==OPENGL_ES2 && ver>=Version(3, 0))
+			formatted += " es";
+		formatted += '\n';
+	}
+
+	if(api==OPENGL_ES2)
+	{
+		if(s.type==FRAGMENT)
+			formatted += "precision mediump float;\n";
+	}
+
 	Visitor::apply(s);
 }
 
@@ -1494,16 +1508,18 @@ void ProgramCompiler::NodeRemover::visit(VariableDeclaration &var)
 
 
 ProgramCompiler::LegacyConverter::LegacyConverter():
+	target_api(get_gl_api()),
 	target_version(get_glsl_version()),
 	frag_out(0)
 { }
 
 ProgramCompiler::LegacyConverter::LegacyConverter(const Version &v):
+	target_api(get_gl_api()),
 	target_version(v),
 	frag_out(0)
 { }
 
-bool ProgramCompiler::LegacyConverter::check_version(const Version &feature_version)
+bool ProgramCompiler::LegacyConverter::check_version(const Version &feature_version) const
 {
 	if(target_version<feature_version)
 		return false;
@@ -1513,9 +1529,17 @@ bool ProgramCompiler::LegacyConverter::check_version(const Version &feature_vers
 	return true;
 }
 
+bool ProgramCompiler::LegacyConverter::supports_unified_interface_syntax() const
+{
+	if(target_api==OPENGL_ES2)
+		return check_version(Version(3, 0));
+	else
+		return check_version(Version(1, 30));
+}
+
 void ProgramCompiler::LegacyConverter::visit(VariableReference &var)
 {
-	if(var.declaration==frag_out && !check_version(Version(1, 30)))
+	if(var.declaration==frag_out && !supports_unified_interface_syntax())
 	{
 		var.name = "gl_FragColor";
 		var.declaration = 0;
@@ -1530,13 +1554,21 @@ void ProgramCompiler::LegacyConverter::visit(VariableReference &var)
 void ProgramCompiler::LegacyConverter::visit(Assignment &assign)
 {
 	TraversingVisitor::visit(assign);
-	if(assign.target_declaration==frag_out && !check_version(Version(1, 30)))
+	if(assign.target_declaration==frag_out && !supports_unified_interface_syntax())
 		assign.target_declaration = 0;
 }
 
+bool ProgramCompiler::LegacyConverter::supports_unified_sampling_functions() const
+{
+	if(target_api==OPENGL_ES2)
+		return check_version(Version(3, 0));
+	else
+		return check_version(Version(1, 30));
+}
+
 void ProgramCompiler::LegacyConverter::visit(FunctionCall &call)
 {
-	if(call.name=="texture" && !call.declaration && !check_version(Version(1, 30)))
+	if(call.name=="texture" && !call.declaration && !supports_unified_sampling_functions())
 	{
 		vector<RefPtr<Expression> >::iterator i = call.arguments.begin();
 		if(i!=call.arguments.end())
@@ -1561,9 +1593,17 @@ void ProgramCompiler::LegacyConverter::visit(FunctionCall &call)
 		TraversingVisitor::visit(call);
 }
 
+bool ProgramCompiler::LegacyConverter::supports_interface_layouts() const
+{
+	if(target_api==OPENGL_ES2)
+		return check_version(Version(3, 0));
+	else
+		return check_version(Version(3, 30));
+}
+
 void ProgramCompiler::LegacyConverter::visit(VariableDeclaration &var)
 {
-	if(var.layout && !check_version(Version(3, 30)))
+	if(var.layout && !supports_interface_layouts())
 	{
 		vector<Layout::Qualifier>::iterator i;
 		for(i=var.layout->qualifiers.begin(); (i!=var.layout->qualifiers.end() && i->identifier!="location"); ++i) ;
@@ -1586,7 +1626,7 @@ void ProgramCompiler::LegacyConverter::visit(VariableDeclaration &var)
 		}
 	}
 
-	if((var.interface=="in" || var.interface=="out") && !check_version(Version(1, 30)))
+	if((var.interface=="in" || var.interface=="out") && !supports_unified_interface_syntax())
 	{
 		if(stage->type==FRAGMENT && var.interface=="out")
 		{
@@ -1598,9 +1638,22 @@ void ProgramCompiler::LegacyConverter::visit(VariableDeclaration &var)
 	TraversingVisitor::visit(var);
 }
 
+bool ProgramCompiler::LegacyConverter::supports_interface_blocks(const string &iface) const
+{
+	if(target_api==OPENGL_ES2)
+	{
+		if(iface=="uniform")
+			return check_version(Version(3, 0));
+		else
+			return check_version(Version(3, 20));
+	}
+	else
+		return check_version(Version(1, 50));
+}
+
 void ProgramCompiler::LegacyConverter::visit(InterfaceBlock &iface)
 {
-	if(!check_version(Version(1, 50)))
+	if(!supports_interface_blocks(iface.interface))
 		flatten_block(iface.members);
 }
 
diff --git a/source/programcompiler.h b/source/programcompiler.h
index e159078a..a84ccb8a 100644
--- a/source/programcompiler.h
+++ b/source/programcompiler.h
@@ -328,6 +328,7 @@ private:
 
 	struct LegacyConverter: BlockModifier
 	{
+		GLApi target_api;
 		Version target_version;
 		std::string type;
 		ProgramSyntax::VariableDeclaration *frag_out;
@@ -335,12 +336,16 @@ private:
 		LegacyConverter();
 		LegacyConverter(const Version &);
 
-		bool check_version(const Version &);
+		bool check_version(const Version &) const;
 		using Visitor::visit;
+		bool supports_unified_interface_syntax() const;
 		virtual void visit(ProgramSyntax::VariableReference &);
 		virtual void visit(ProgramSyntax::Assignment &);
+		bool supports_unified_sampling_functions() const;
 		virtual void visit(ProgramSyntax::FunctionCall &);
+		bool supports_interface_layouts() const;
 		virtual void visit(ProgramSyntax::VariableDeclaration &);
+		bool supports_interface_blocks(const std::string &) const;
 		virtual void visit(ProgramSyntax::InterfaceBlock &);
 	};
 
-- 
2.43.0