[cogl/cogl-1.12] framebuffer: drop _ALLOCATE_FLAG_DEPTH24_STENCIL8

[Robert Bragg <rbragg src gnome org>]

commit 7b5b0bef8356b5d3f081d80505175c923510ea22
Author: Robert Bragg <robert linux intel com>
Date:   Thu Sep 6 10:14:44 2012 +0100

    framebuffer: drop _ALLOCATE_FLAG_DEPTH24_STENCIL8
    
    There are two extensions, GL_OES_packed_depth_stencil and
    GL_EXT_packed_depth_stencil, that inform us that the hardware supports
    packing the depth and stencil values together into one format.
    
    The OES extension is the GLES equivalent of the EXT extension and the
    two extensions provide the same enums with basically the same semantics,
    except that the EXT extension is a lot more wordy due to a larger number
    of features in the full OpenGL api and the OES extension has some
    asymmetric limitations on when the GL_DEPTH_STENCIL and
    GL_DEPTH24_STENCIL8 enums can be used as internal formats.
    
    GL_OES_packed_depth_stencil doesn't allow the GL_DEPTH_STENCIL enum
    to be passed to glRenderbufferStorage (GL_DEPTH24_STENCIL8 should be
    used instead) and GL_OES_packed_depth_stencil doesn't allow
    GL_DEPTH24_STENCIL8 to be passed as an internal format to glTexImage2D.
    
    We had been handling the two extensions differently in Cogl by calling
    try_creating_fbo with different flags depending on whether the OES or
    EXT extension was available and passing GL_DEPTH_STENCIL to
    glRenderbufferStorage when we have the EXT extension or
    GL_DEPTH24_STENCIL8 with the OES extension.
    
    To localize the code that deals with the differences between the
    extensions this patch does away with the need for separate flags
    so we now just have COGL_OFFSCREEN_ALLOCATE_FLAG_DEPTH_DEPTH_STENCIL and
    right before calling glRenderbufferStorage we check which extension we
    are using to decide whether to use the GL_DEPTH_STENCIL or
    GL_DEPTH24_STENCIL8 enums.
    
    (cherry picked from commit 88a05fac6609f88c0f46d9df2611d9fbaf159939)

 cogl/cogl-framebuffer-private.h |    5 ++---
 cogl/cogl-framebuffer.c         |   37 +++++++++++++++++++++----------------
 2 files changed, 23 insertions(+), 19 deletions(-)
---
diff --git a/cogl/cogl-framebuffer-private.h b/cogl/cogl-framebuffer-private.h
index 9922a1a..fe3fe25 100644
--- a/cogl/cogl-framebuffer-private.h
+++ b/cogl/cogl-framebuffer-private.h
@@ -168,9 +168,8 @@ struct _CoglFramebuffer
 
 typedef enum {
   COGL_OFFSCREEN_ALLOCATE_FLAG_DEPTH_STENCIL    = 1L<<0,
-  COGL_OFFSCREEN_ALLOCATE_FLAG_DEPTH24_STENCIL8 = 1L<<1,
-  COGL_OFFSCREEN_ALLOCATE_FLAG_DEPTH            = 1L<<2,
-  COGL_OFFSCREEN_ALLOCATE_FLAG_STENCIL          = 1L<<3
+  COGL_OFFSCREEN_ALLOCATE_FLAG_DEPTH            = 1L<<1,
+  COGL_OFFSCREEN_ALLOCATE_FLAG_STENCIL          = 1L<<2
 } CoglOffscreenAllocateFlags;
 
 typedef struct _CoglGLFramebuffer
diff --git a/cogl/cogl-framebuffer.c b/cogl/cogl-framebuffer.c
index f94bd00..31bf009 100644
--- a/cogl/cogl-framebuffer.c
+++ b/cogl/cogl-framebuffer.c
@@ -831,11 +831,26 @@ try_creating_renderbuffers (CoglContext *ctx,
   GList *renderbuffers = NULL;
   GLuint gl_depth_stencil_handle;
 
-  if (flags & (COGL_OFFSCREEN_ALLOCATE_FLAG_DEPTH_STENCIL |
-               COGL_OFFSCREEN_ALLOCATE_FLAG_DEPTH24_STENCIL8))
+  if (flags & COGL_OFFSCREEN_ALLOCATE_FLAG_DEPTH_STENCIL)
     {
-      GLenum format = ((flags & COGL_OFFSCREEN_ALLOCATE_FLAG_DEPTH_STENCIL) ?
-                       GL_DEPTH_STENCIL : GL_DEPTH24_STENCIL8);
+      GLenum format;
+
+      /* Although GL_OES_packed_depth_stencil is mostly equivalent to
+       * GL_EXT_packed_depth_stencil, one notable difference is that
+       * GL_OES_packed_depth_stencil doesn't allow GL_DEPTH_STENCIL to
+       * be passed as an internal format to glRenderbufferStorage.
+       */
+      if (ctx->private_feature_flags &
+          COGL_PRIVATE_FEATURE_EXT_PACKED_DEPTH_STENCIL)
+        format = GL_DEPTH_STENCIL;
+      else
+        {
+          _COGL_RETURN_VAL_IF_FAIL (
+                                  ctx->private_feature_flags &
+                                  COGL_PRIVATE_FEATURE_OES_PACKED_DEPTH_STENCIL,
+                                  NULL);
+          format = GL_DEPTH24_STENCIL8;
+        }
 
       /* Create a renderbuffer for depth and stenciling */
       GE (ctx, glGenRenderbuffers (1, &gl_depth_stencil_handle));
@@ -1073,7 +1088,8 @@ _cogl_offscreen_allocate (CoglOffscreen *offscreen,
                          gl_framebuffer)) ||
 
       ((ctx->private_feature_flags &
-        COGL_PRIVATE_FEATURE_EXT_PACKED_DEPTH_STENCIL) &&
+        (COGL_PRIVATE_FEATURE_EXT_PACKED_DEPTH_STENCIL |
+         COGL_PRIVATE_FEATURE_OES_PACKED_DEPTH_STENCIL)) &&
        try_creating_fbo (ctx,
                          offscreen->texture,
                          offscreen->texture_level,
@@ -1083,17 +1099,6 @@ _cogl_offscreen_allocate (CoglOffscreen *offscreen,
                          flags = COGL_OFFSCREEN_ALLOCATE_FLAG_DEPTH_STENCIL,
                          gl_framebuffer)) ||
 
-      ((ctx->private_feature_flags &
-        COGL_PRIVATE_FEATURE_OES_PACKED_DEPTH_STENCIL) &&
-       try_creating_fbo (ctx,
-                         offscreen->texture,
-                         offscreen->texture_level,
-                         offscreen->texture_level_width,
-                         offscreen->texture_level_height,
-                         &fb->config,
-                         flags = COGL_OFFSCREEN_ALLOCATE_FLAG_DEPTH24_STENCIL8,
-                         gl_framebuffer)) ||
-
       try_creating_fbo (ctx,
                         offscreen->texture,
                         offscreen->texture_level,