From 5c0fedf190b58493402a5a74687e1662bc90d6c6 Mon Sep 17 00:00:00 2001
From: Robert Beckebans <robert.beckebans@gmail.com>
Date: Sun, 11 May 2014 12:19:10 +0200
Subject: [PATCH] Patched GLEW to get the extensions with OpenGL >= 3.2 for the
 case that glGetString(GL_EXTENSIONS) fails

---
 neo/libs/glew/src/glew.c           | 94 ++++++++++++++++++++++++++----
 neo/renderer/RenderSystem_init.cpp |  2 +-
 neo/sys/win32/win_glimp.cpp        |  4 +-
 3 files changed, 85 insertions(+), 15 deletions(-)

diff --git a/neo/libs/glew/src/glew.c b/neo/libs/glew/src/glew.c
index d075b524..9d2ead70 100644
--- a/neo/libs/glew/src/glew.c
+++ b/neo/libs/glew/src/glew.c
@@ -9468,15 +9468,75 @@ static GLboolean _glewInit_GL_WIN_swap_hint (GLEW_CONTEXT_ARG_DEF_INIT)
 
 /* ------------------------------------------------------------------------- */
 
+// RB: use this instead of glGetString(GL_EXTENSIONS) for OpenGL >= 3.0
+static const GLubyte* _glewGetExtensions(void) {
+    static int s_init = 0;
+    static GLubyte s_array[16384];
+    static const GLubyte* s_ret = 0;
+
+    if (s_init == 0) {
+        PFNGLGETSTRINGIPROC localGetStringi = 0;
+
+        s_init = 1;
+
+        localGetStringi = (PFNGLGETSTRINGIPROC)glewGetProcAddress((const GLubyte*)"glGetStringi");
+
+        if (localGetStringi) {
+            GLint num_extensions = 0;
+            GLint extension_idx = 0;
+            GLuint arr_idx = 0;
+
+            glGetIntegerv(GL_NUM_EXTENSIONS, &num_extensions);
+
+            for ( ; extension_idx < num_extensions; ++extension_idx) {
+                const GLubyte* extension = localGetStringi(GL_EXTENSIONS, extension_idx);
+
+                if (!extension) {
+                    return 0;
+                }
+
+                while (arr_idx < sizeof(s_array) && *extension != '\0') {
+                    s_array[arr_idx++] = *extension++;
+                }
+
+                if (arr_idx < sizeof(s_array)) {
+                    s_array[arr_idx++] = ' ';
+                }
+            }
+
+            if (arr_idx < sizeof(s_array)) {
+                s_array[arr_idx++] = '\0';
+                s_ret = s_array;
+            }
+        } else {
+            s_ret = glGetString(GL_EXTENSIONS);
+        }
+    }
+
+    return s_ret;
+}
+// RB end
+
 GLboolean GLEWAPIENTRY glewGetExtension (const char* name)
 {    
-  const GLubyte* start;
-  const GLubyte* end;
-  start = (const GLubyte*)glGetString(GL_EXTENSIONS);
-  if (start == 0)
-    return GL_FALSE;
-  end = start + _glewStrLen(start);
-  return _glewSearchExtension(name, start, end);
+	const GLubyte* start;
+	const GLubyte* end;
+	start = (const GLubyte*)glGetString(GL_EXTENSIONS);
+	// RB begin
+	if( start == 0 )
+	{
+		// clear previously generated error
+		glGetError();
+
+		start = _glewGetExtensions();
+		if( start == 0 )
+		{
+			return GL_FALSE;
+		}
+	}
+	// RB end
+	end = start + _glewStrLen(start);
+	return _glewSearchExtension(name, start, end);
 }
 
 /* ------------------------------------------------------------------------- */
@@ -9531,10 +9591,22 @@ GLenum GLEWAPIENTRY glewContextInit (GLEW_CONTEXT_ARG_DEF_LIST)
     CONST_CAST(GLEW_VERSION_1_1)   = GLEW_VERSION_1_2   == GL_TRUE || ( major == 1 && minor >= 1 ) ? GL_TRUE : GL_FALSE;
   }
 
-  /* query opengl extensions string */
-  extStart = glGetString(GL_EXTENSIONS);
-  if (extStart == 0)
-    extStart = (const GLubyte*)"";
+	/* query opengl extensions string */
+	// RB begin
+	extStart = glGetString(GL_EXTENSIONS);
+	if( extStart == 0 )
+	{
+		// clear previously generated error
+		glGetError();
+
+		extStart = _glewGetExtensions();
+		if( extStart == 0 )
+		{
+			extStart = (const GLubyte*)"";
+		}
+	}
+	// RB end
+    
   extEnd = extStart + _glewStrLen(extStart);
 
   /* initialize extensions */
diff --git a/neo/renderer/RenderSystem_init.cpp b/neo/renderer/RenderSystem_init.cpp
index 3983c569..4a9a3fca 100644
--- a/neo/renderer/RenderSystem_init.cpp
+++ b/neo/renderer/RenderSystem_init.cpp
@@ -328,7 +328,7 @@ static void R_CheckPortableExtensions()
 	}
 	
 	// RB: Mesa support
-	//if( idStr::Icmpn( glConfig.renderer_string, "Mesa", 4 ) == 0 || idStr::Icmpn( glConfig.renderer_string, "X.org", 4 ) == 0 )
+	if( idStr::Icmpn( glConfig.renderer_string, "Mesa", 4 ) == 0 || idStr::Icmpn( glConfig.renderer_string, "X.org", 4 ) == 0 )
 	{
 		glConfig.driverType = GLDRV_OPENGL_MESA;
 	}
diff --git a/neo/sys/win32/win_glimp.cpp b/neo/sys/win32/win_glimp.cpp
index 9d15cad5..c043f7a7 100644
--- a/neo/sys/win32/win_glimp.cpp
+++ b/neo/sys/win32/win_glimp.cpp
@@ -1352,8 +1352,7 @@ bool GLimp_Init( glimpParms_t parms )
 		glConfig.physicalScreenWidthInCentimeters = 0.1f * mmWide;
 	}
 	
-	// RB begin
-	/*
+	// RB: we probably have a new OpenGL 3.2 core context so reinitialize GLEW
 	GLenum glewResult = glewInit();
 	if( GLEW_OK != glewResult )
 	{
@@ -1364,7 +1363,6 @@ bool GLimp_Init( glimpParms_t parms )
 	{
 		common->Printf( "Using GLEW %s\n", glewGetString( GLEW_VERSION ) );
 	}
-	*/
 	// RB end
 	
 	// wglSwapinterval, etc