Support specialization constants in the GLSL compiler

[libs/gl.git] / source / glsl / generate.cpp

diff --git a/source/glsl/generate.cpp b/source/glsl/generate.cpp
index 42226a912396171faf0287b4062cbee19fbe5a40..2ac37a6ffae788a16c6cc367dbcf53b9fdb61dcb 100644 (file)
--- a/source/glsl/generate.cpp
+++ b/source/glsl/generate.cpp
@@ -1,4 +1,6 @@
+#include <msp/core/hash.h>
 #include <msp/core/raii.h>
+#include <msp/strings/lexicalcast.h>
 #include "builtin.h"
 #include "generate.h"
 
@@ -73,6 +75,59 @@ void DeclarationCombiner::visit(VariableDeclaration &var)
 }
 
 
+ConstantSpecializer::ConstantSpecializer():
+       values(0)
+{ }
+
+void ConstantSpecializer::apply(Stage &stage, const map<string, int> *v)
+{
+       values = v;
+       stage.content.visit(*this);
+}
+
+void ConstantSpecializer::visit(VariableDeclaration &var)
+{
+       bool specializable = false;
+       if(var.layout)
+       {
+               vector<Layout::Qualifier> &qualifiers = var.layout->qualifiers;
+               for(vector<Layout::Qualifier>::iterator i=qualifiers.begin(); i!=qualifiers.end(); ++i)
+                       if(i->name=="constant_id")
+                       {
+                               specializable = true;
+                               if(values)
+                                       qualifiers.erase(i);
+                               else if(i->value==-1)
+                                       i->value = hash32(var.name)&0x7FFFFFFF;
+                               break;
+                       }
+
+               if(qualifiers.empty())
+                       var.layout = 0;
+       }
+
+       if(specializable && values)
+       {
+               map<string, int>::const_iterator i = values->find(var.name);
+               if(i!=values->end())
+               {
+                       RefPtr<Literal> literal = new Literal;
+                       if(var.type=="bool")
+                       {
+                               literal->token = (i->second ? "true" : "false");
+                               literal->value = static_cast<bool>(i->second);
+                       }
+                       else if(var.type=="int")
+                       {
+                               literal->token = lexical_cast<string>(i->second);
+                               literal->value = i->second;
+                       }
+                       var.init_expression = literal;
+               }
+       }
+}
+
+
 void BlockResolver::enter(Block &block)
 {
        block.parent = current_block;