configure: Include gl2ext.h or glext.h under GLES

Under big GL, glext.h is included automatically by gl.h. However under
GLES this doesn't appear to happen so it has to be included explicitly
to get the defines for extensions. This patch changes the
clutter_gl_header to be called cogl_gl_headers and it can now take a
space seperated list of multiple headers. This is then later converted
to a list of #include lines which ends up cogl-defines.h. The gles2
and gles1 backends now add their respective ext header to this list.

clutter/cogl/cogl/cogl-defines.h.in

@@ -25,7 +25,7 @@
 #define __COGL_DEFINES_H__
 
 #include <glib.h>
-#include <@CLUTTER_GL_HEADER@>
+@COGL_GL_HEADER_INCLUDES@
 
 G_BEGIN_DECLS
 

configure.ac

@@ -131,7 +131,7 @@ FLAVOUR_CFLAGS=""
 CLUTTER_WINSYS_BASE=
 CLUTTER_WINSYS_BASE_LIB=
 CLUTTER_WINSYS=
-clutter_gl_header=""
+cogl_gl_headers=""
 glesversion=1.1
 use_gles2_wrapper=no
 experimental_backend=no
@@ -160,7 +160,7 @@ AS_CASE([$CLUTTER_FLAVOUR],
 
         [glx],
         [
-          clutter_gl_header="GL/gl.h"
+          cogl_gl_headers="GL/gl.h"
           CLUTTER_STAGE_TYPE="CLUTTER_TYPE_STAGE_GLX"
 
           SUPPORT_X11=1
@@ -184,7 +184,7 @@ AS_CASE([$CLUTTER_FLAVOUR],
 
         [opengl-egl-xlib],
         [
-          clutter_gl_header="GL/gl.h"
+          cogl_gl_headers="GL/gl.h"
           CLUTTER_STAGE_TYPE="CLUTTER_TYPE_STAGE_EGL"
 
           SUPPORT_X11=1
@@ -267,7 +267,7 @@ AS_CASE([$CLUTTER_FLAVOUR],
         [osx],
         [
           experimental_backend="yes"
-          clutter_gl_header="OpenGL/gl.h"
+          cogl_gl_headers="OpenGL/gl.h"
           CLUTTER_STAGE_TYPE="CLUTTER_TYPE_STAGE_OSX"
 
           AC_DEFINE([HAVE_CLUTTER_OSX], [1], [Have the OSX backend])
@@ -284,7 +284,7 @@ AS_CASE([$CLUTTER_FLAVOUR],
 
         [win32],
         [
-          clutter_gl_header="GL/gl.h"
+          cogl_gl_headers="GL/gl.h"
           CLUTTER_STAGE_TYPE="CLUTTER_TYPE_STAGE_WIN32"
           AC_DEFINE([HAVE_CLUTTER_WIN32], [1], [Have the Win32 backend])
           AC_DEFINE([COGL_HAS_WIN32_SUPPORT], [1], [Cogl supports the win32 window system])
@@ -370,7 +370,7 @@ AS_IF([test "x$COGL_DRIVER" = "xgles"],
 
           [1*],
           [
-            clutter_gl_header="GLES/gl.h"
+            cogl_gl_headers="GLES/gl.h GLES/glext.h"
 
             AC_DEFINE([HAVE_COGL_GLES], 1, [Have GL/ES for rendering])
             AC_SUBST(COGL_GLES_VERSION, [COGL_HAS_GLES1])
@@ -380,7 +380,7 @@ AS_IF([test "x$COGL_DRIVER" = "xgles"],
                NEED_SEPARATE_EGL=yes
               ],
               [
-                AC_CHECK_HEADERS([$clutter_gl_header],
+                AC_CHECK_HEADERS([$cogl_gl_headers],
                                  [],
                                  [AC_MSG_ERROR([Unable to locate required GLES headers])])
 
@@ -421,7 +421,7 @@ AS_IF([test "x$COGL_DRIVER" = "xgles"],
 
           [2*],
           [
-            clutter_gl_header="GLES2/gl2.h"
+            cogl_gl_headers="GLES2/gl2.h GLES2/gl2ext.h"
             use_gles2_wrapper=yes
             AC_DEFINE([HAVE_COGL_GLES2], 1, [Have GL/ES for rendering])
             AC_SUBST(COGL_GLES_VERSION, [COGL_HAS_GLES2])
@@ -429,7 +429,7 @@ AS_IF([test "x$COGL_DRIVER" = "xgles"],
             PKG_CHECK_EXISTS([glesv2],
               [BACKEND_PC_FILES="$BACKEND_PC_FILES glesv2"],
               [
-                AC_CHECK_HEADERS([$clutter_gl_header],
+                AC_CHECK_HEADERS([$cogl_gl_headers],
                                  [],
                                  [AC_MSG_ERROR([Unable to locate required GLES headers])])
 
@@ -454,7 +454,7 @@ AS_IF([test "x$COGL_DRIVER" = "xgles"],
 
           [fruity],
           [
-            clutter_gl_header="GLES/gl.h"
+            cogl_gl_headers="GLES/gl.h GLES/glext.h"
             AC_DEFINE([HAVE_COGL_GLES], 1, [Have GL/ES for rendering])
             AC_SUBST(COGL_GLES_VERSION, [COGL_HAS_GLES1])
 
@@ -505,8 +505,17 @@ done;
 
 AC_SUBST(COGL_DEFINES)
 
-AS_IF([test "x$clutter_gl_header" = "x"], [AC_MSG_ERROR([Internal error: no GL header set])])
+AS_IF([test "x$cogl_gl_headers" = "x"], [AC_MSG_ERROR([Internal error: no GL header set])])
-CLUTTER_GL_HEADER=$clutter_gl_header
+
+dnl cogl_gl_headers is a space separate list of headers to
+dnl include. We'll now convert them to a single variable with a
+dnl #include line for each header
+COGL_GL_HEADER_INCLUDES=""
+for x in $cogl_gl_headers; do
+  COGL_GL_HEADER_INCLUDES="$COGL_GL_HEADER_INCLUDES
+#include <$x>"
+done;
+AC_SUBST(COGL_GL_HEADER_INCLUDES)
 
 
 dnl === Clutter substitutions =================================================
@@ -516,7 +525,6 @@ AC_SUBST([CLUTTER_WINSYS])
 # The same goes for the winsys-base...
 AC_SUBST([CLUTTER_WINSYS_BASE])
 AC_SUBST([CLUTTER_WINSYS_BASE_LIB])
-AC_SUBST(CLUTTER_GL_HEADER)
 AC_SUBST(CLUTTER_STAGE_TYPE)
 AC_SUBST(CLUTTER_SONAME_INFIX)
 
@@ -1108,7 +1116,7 @@ fi
 echo ""
 echo " • COGL Backend:"
 echo "        Driver: ${COGL_DRIVER}"
-echo "        GL header: ${CLUTTER_GL_HEADER}"
+echo "        GL header: ${cogl_gl_headers}"
 
 if test "x$COGL_DRIVER" = "xgles"; then
   if test "x$use_gles2_wrapper" = "xyes"; then