From 00ffc97eda26687f98f04226c2da728e2ca1220e Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Mon, 20 Oct 2014 11:56:10 +0300
Subject: [PATCH] Prefer glMapBufferRange over glMapBuffer

OpenGL ES does not have glMapBuffer.
---
 extensions/arb_map_buffer_range.glext |  1 +
 source/buffer.cpp                     | 20 ++++++++++++++++++--
 2 files changed, 19 insertions(+), 2 deletions(-)
 create mode 100644 extensions/arb_map_buffer_range.glext

diff --git a/extensions/arb_map_buffer_range.glext b/extensions/arb_map_buffer_range.glext
new file mode 100644
index 00000000..643bb9ea
--- /dev/null
+++ b/extensions/arb_map_buffer_range.glext
@@ -0,0 +1 @@
+extension ARB_map_buffer_range
diff --git a/source/buffer.cpp b/source/buffer.cpp
index 1226dbe3..080c3fb3 100644
--- a/source/buffer.cpp
+++ b/source/buffer.cpp
@@ -1,4 +1,5 @@
 #include <stdexcept>
+#include <msp/gl/extensions/arb_map_buffer_range.h>
 #include "buffer.h"
 #include "error.h"
 #include "mesh.h"
@@ -64,8 +65,23 @@ BufferRange *Buffer::create_range(unsigned s, unsigned o)
 
 void *Buffer::map(BufferAccess access)
 {
-	BindRestore _bind(this, type);
-	return glMapBuffer(type, access);
+	if(ARB_map_buffer_range)
+	{
+		BindRestore _bind(this, type);
+		GLenum access_bits = 0;
+		if(access==READ_ONLY)
+			access_bits = GL_MAP_READ_BIT;
+		else if(access==WRITE_ONLY)
+			access_bits = GL_MAP_WRITE_BIT;
+		else if(access==READ_WRITE)
+			access_bits = GL_MAP_READ_BIT|GL_MAP_WRITE_BIT;
+		return glMapBufferRange(type, 0, size, access_bits);
+	}
+	else
+	{
+		BindRestore _bind(this, type);
+		return glMapBuffer(type, access);
+	}
 }
 
 bool Buffer::unmap()
-- 
2.43.0