Dynamically load the GL or GLES library

The GL or GLES library is now dynamically loaded by the CoglRenderer
so that it can choose between GL, GLES1 and GLES2 at runtime. The
library is loaded by the renderer because it needs to be done before
calling eglInitialize. There is a new environment variable called
COGL_DRIVER to choose between gl, gles1 or gles2.

The #ifdefs for HAVE_COGL_GL, HAVE_COGL_GLES and HAVE_COGL_GLES2 have
been changed so that they don't assume the ifdefs are mutually
exclusive. They haven't been removed entirely so that it's possible to
compile the GLES backends without the the enums from the GL headers.

When using GLX the winsys additionally dynamically loads libGL because
that also contains the GLX API. It can't be linked in directly because
that would probably conflict with the GLES API if the EGL is
selected. When compiling with EGL support the library links directly
to libEGL because it doesn't contain any GL API so it shouldn't have
any conflicts.

When building for WGL or OSX Cogl still directly links against the GL
API so there is a #define in config.h so that Cogl won't try to dlopen
the library.

Cogl-pango previously had a #ifdef to detect when the GL backend is
used so that it can sneakily pass GL_QUADS to
cogl_vertex_buffer_draw. This is now changed so that it queries the
CoglContext for the backend. However to get this to work Cogl now
needs to export the _cogl_context_get_default symbol and cogl-pango
needs some extra -I flags to so that it can include
cogl-context-private.h

1 files changed, 18 insertions, 20 deletions

diff --git a/cogl/cogl.c b/cogl/cogl.c
index b77a6230..7b2990ec 100644
--- a/cogl/cogl.c
+++ b/cogl/cogl.c
@@ -164,15 +164,7 @@ toggle_flag (CoglContext *ctx,
   return FALSE;
 }
 
-#ifdef HAVE_COGL_GLES2
-
-/* Under GLES2 there are no builtin client flags so toggle_client_flag
-   should never be reached */
-
-#define toggle_client_flag(ctx, new_flags, flag, gl_flag) \
-  g_assert (((new_flags) & (flag)) == 0)
-
-#else /* HAVE_COGL_GLES2 */
+#if defined (HAVE_COGL_GL) || defined (HAVE_COGL_GLES)
 
 static gboolean
 toggle_client_flag (CoglContext *ctx,
@@ -180,6 +172,8 @@ toggle_client_flag (CoglContext *ctx,
 		    unsigned long flag,
 		    GLenum gl_flag)
 {
+  g_return_val_if_fail (ctx->driver != COGL_DRIVER_GLES2, FALSE);
+
   /* Toggles and caches a single client-side enable flag
    * on or off by comparing to current state
    */
@@ -201,7 +195,7 @@ toggle_client_flag (CoglContext *ctx,
   return FALSE;
 }
 
-#endif /* HAVE_COGL_GLES2 */
+#endif
 
 void
 _cogl_enable (unsigned long flags)
@@ -215,13 +209,18 @@ _cogl_enable (unsigned long flags)
                COGL_ENABLE_BACKFACE_CULLING,
                GL_CULL_FACE);
 
-  toggle_client_flag (ctx, flags,
-		      COGL_ENABLE_VERTEX_ARRAY,
-		      GL_VERTEX_ARRAY);
+#if defined (HAVE_COGL_GL) || defined (HAVE_COGL_GLES)
+  if (ctx->driver != COGL_DRIVER_GLES2)
+    {
+      toggle_client_flag (ctx, flags,
+                          COGL_ENABLE_VERTEX_ARRAY,
+                          GL_VERTEX_ARRAY);
 
-  toggle_client_flag (ctx, flags,
-		      COGL_ENABLE_COLOR_ARRAY,
-		      GL_COLOR_ARRAY);
+      toggle_client_flag (ctx, flags,
+                          COGL_ENABLE_COLOR_ARRAY,
+                          GL_COLOR_ARRAY);
+    }
+#endif
 }
 
 unsigned long
@@ -557,9 +556,9 @@ _cogl_read_pixels_with_rowstride (int x,
      GL_RGBA/GL_UNSIGNED_BYTE and convert if necessary. We also need
      to use this intermediate buffer if the rowstride has padding
      because GLES does not support setting GL_ROW_LENGTH */
-#ifndef COGL_HAS_GL
-  if (gl_format != GL_RGBA || gl_type != GL_UNSIGNED_BYTE ||
-      rowstride != 4 * width)
+  if (ctx->driver != COGL_DRIVER_GL &&
+      (gl_format != GL_RGBA || gl_type != GL_UNSIGNED_BYTE ||
+       rowstride != 4 * width))
     {
       CoglBitmap *tmp_bmp, *dst_bmp;
       guint8 *tmp_data = g_malloc (width * height * 4);
@@ -599,7 +598,6 @@ _cogl_read_pixels_with_rowstride (int x,
       cogl_object_unref (tmp_bmp);
     }
   else
-#endif
     {
       ctx->texture_driver->prep_gl_for_pixels_download (rowstride, bpp);