[mutter] Fix compilation with older libGL

[Owen Taylor <otaylor src gnome org>]

commit bdb3be708436cef1ac55405b9a9c150c97b522c7
Author: Owen W. Taylor <otaylor fishsoup net>
Date:   Tue Nov 24 15:53:32 2009 -0500

    Fix compilation with older libGL
    
    the mutlitexture and texture_rectangle extensions have recently
    been incorporated into the GL core; fixes needed to work with
    libGL that proceeds that:
    
    GL_TEXTURE_RECTANGLE_ARB - use _ARB name
    glActiveTextureARB() - use get_proc_address
    
    https://bugzilla.gnome.org/show_bug.cgi?id=602870

 src/compositor/mutter-texture-tower.c |   14 ++++++++------
 1 files changed, 8 insertions(+), 6 deletions(-)
---
diff --git a/src/compositor/mutter-texture-tower.c b/src/compositor/mutter-texture-tower.c
index cd5e3e9..36469a1 100644
--- a/src/compositor/mutter-texture-tower.c
+++ b/src/compositor/mutter-texture-tower.c
@@ -32,6 +32,7 @@
 #endif
 
 #if !CLUTTER_CHECK_VERSION(1,1,3)
+static PFNGLACTIVETEXTUREPROC activeTexture;
 static PFNGLGENFRAMEBUFFERSPROC genFramebuffers;
 static PFNGLDELETEFRAMEBUFFERSPROC deleteFramebuffers;
 static PFNGLBINDFRAMEBUFFERPROC bindFramebuffer;
@@ -488,6 +489,7 @@ initialize_gl_functions (void)
     {
       initialized = TRUE;
 
+      activeTexture = (PFNGLACTIVETEXTUREPROC) cogl_get_proc_address ("glActiveTextureARB");
       genFramebuffers = (PFNGLGENFRAMEBUFFERSPROC) cogl_get_proc_address ("glGenFramebuffersEXT");
       deleteFramebuffers = (PFNGLDELETEFRAMEBUFFERSPROC) cogl_get_proc_address ("glDeleteFramebuffersEXT");
       bindFramebuffer = (PFNGLBINDFRAMEBUFFERPROC) cogl_get_proc_address ("glBindFramebufferEXT");
@@ -550,9 +552,9 @@ texture_tower_revalidate_fbo (MutterTextureTower *tower,
 
   cogl_texture_get_gl_texture (source_texture, &source_gl_tex, &source_gl_target);
 
-  glActiveTextureARB (GL_TEXTURE0_ARB);
+  (*activeTexture) (GL_TEXTURE0_ARB);
   if (source_gl_target == GL_TEXTURE_2D)
-    glDisable (GL_TEXTURE_RECTANGLE);
+    glDisable (GL_TEXTURE_RECTANGLE_ARB);
   else
     glDisable (GL_TEXTURE_2D);
   glEnable (source_gl_target);
@@ -568,12 +570,12 @@ texture_tower_revalidate_fbo (MutterTextureTower *tower,
    * than three are used by Mutter and all GL implementations we care
    * about will support at least 3.
    */
-  glActiveTextureARB (GL_TEXTURE1_ARB);
+  (*activeTexture) (GL_TEXTURE1_ARB);
   glDisable (GL_TEXTURE_2D);
-  glDisable (GL_TEXTURE_RECTANGLE);
-  glActiveTextureARB (GL_TEXTURE2_ARB);
+  glDisable (GL_TEXTURE_RECTANGLE_ARB);
+  (*activeTexture) (GL_TEXTURE2_ARB);
   glDisable (GL_TEXTURE_2D);
-  glDisable (GL_TEXTURE_RECTANGLE);
+  glDisable (GL_TEXTURE_RECTANGLE_ARB);
 
   glViewport (0, 0, dest_texture_width, dest_texture_height);