From: Mikko Rasa <tdb@tdb.fi>
Date: Wed, 15 Aug 2012 19:32:28 +0000 (+0300)
Subject: Generate a hash describing the layout of uniforms in a Program
X-Git-Url: http://git.tdb.fi/?p=libs%2Fgl.git;a=commitdiff_plain;h=cc5e2fb2a0fbb48a9780c9a7c363d1712e459740

Generate a hash describing the layout of uniforms in a Program

This allows easy recognition of whether two Programs have compatible
uniform layouts and could use shared data.
---

diff --git a/source/program.cpp b/source/program.cpp
index ea1f30d2..587a3fb0 100644
--- a/source/program.cpp
+++ b/source/program.cpp
@@ -1,4 +1,6 @@
 #include <algorithm>
+#include <msp/core/hash.h>
+#include <msp/strings/format.h>
 #include "arb_shader_objects.h"
 #include "arb_vertex_shader.h"
 #include "error.h"
@@ -239,6 +241,16 @@ void Program::link()
 			uniforms[name] = info;
 		}
 	}
+
+	string layout_descriptor;
+	for(map<string, UniformInfo>::const_iterator i = uniforms.begin(); i!=uniforms.end(); ++i)
+		if(i->second.location>=0)
+		{
+			if(!layout_descriptor.empty())
+				layout_descriptor += '\n';
+			layout_descriptor += format("%d:%s:%x", i->second.location, i->second.name, i->second.type);
+		}
+	uniform_layout_hash = hash32(layout_descriptor);
 }
 
 string Program::get_info_log() const
diff --git a/source/program.h b/source/program.h
index b6007073..a1f454e9 100644
--- a/source/program.h
+++ b/source/program.h
@@ -65,6 +65,7 @@ private:
 	std::list<Shader *> owned_data;
 	bool linked;
 	std::map<std::string, UniformInfo> uniforms;
+	unsigned uniform_layout_hash;
 
 public:
 	Program();
@@ -88,6 +89,7 @@ public:
 	bool is_linked() const { return linked; }
 	std::string get_info_log() const;
 	void bind() const;
+	unsigned get_uniform_layout_hash() const { return uniform_layout_hash; }
 	int get_uniform_location(const std::string &) const;
 
 	static void unbind();