make COGL_FEATURE_VBOS a private feature

Cogl provides a consistent public interface regardless of whether the
underlying GL driver supports VBOs so it doesn't make much sense to have
this feature as part of the public api.  We can't break the api by
removing the enum but at least we no longer ever set the feature flag.

We now have a replacement private feature flag COGL_PRIVATE_FEATURE_VBOS
which cogl now checks for internally.

Reviewed-by: Neil Roberts <neil@linux.intel.com>

cogl/cogl-attribute-buffer.c

@@ -32,6 +32,7 @@
 #include "cogl-object-private.h"
 #include "cogl-attribute-buffer.h"
 #include "cogl-attribute-buffer-private.h"
+#include "cogl-context-private.h"
 
 static void _cogl_attribute_buffer_free (CoglAttributeBuffer *array);
 
@@ -43,7 +44,9 @@ cogl_attribute_buffer_new (gsize bytes, const void *data)
   CoglAttributeBuffer *array = g_slice_new (CoglAttributeBuffer);
   gboolean use_malloc;
 
-  if (!cogl_features_available (COGL_FEATURE_VBOS))
+  _COGL_GET_CONTEXT (ctx, NULL);
+
+  if (!(ctx->private_feature_flags & COGL_PRIVATE_FEATURE_VBOS))
     use_malloc = TRUE;
   else
     use_malloc = FALSE;

cogl/cogl-context.c

@@ -74,7 +74,7 @@ static void
 _cogl_init_feature_overrides (CoglContext *ctx)
 {
   if (G_UNLIKELY (COGL_DEBUG_ENABLED (COGL_DEBUG_DISABLE_VBOS)))
-    ctx->feature_flags &= ~COGL_FEATURE_VBOS;
+    ctx->private_feature_flags &= ~COGL_PRIVATE_FEATURE_VBOS;
 
   if (G_UNLIKELY (COGL_DEBUG_ENABLED (COGL_DEBUG_DISABLE_PBOS)))
     ctx->private_feature_flags &= ~COGL_PRIVATE_FEATURE_PBOS;

cogl/cogl-index-buffer.c

@@ -32,6 +32,7 @@
 #include "cogl-object-private.h"
 #include "cogl-indices.h"
 #include "cogl-indices-private.h"
+#include "cogl-context-private.h"
 
 static void _cogl_index_buffer_free (CoglIndexBuffer *indices);
 
@@ -46,7 +47,9 @@ cogl_index_buffer_new (gsize bytes)
   CoglIndexBuffer *indices = g_slice_new (CoglIndexBuffer);
   gboolean use_malloc;
 
-  if (!cogl_features_available (COGL_FEATURE_VBOS))
+  _COGL_GET_CONTEXT (ctx, NULL);
+
+  if (!(ctx->private_feature_flags & COGL_PRIVATE_FEATURE_VBOS))
     use_malloc = TRUE;
   else
     use_malloc = FALSE;

cogl/cogl-internal.h

@@ -132,7 +132,8 @@ typedef enum
   COGL_PRIVATE_FEATURE_STENCIL_BUFFER = 1L<<2,
   COGL_PRIVATE_FEATURE_OFFSCREEN_BLIT = 1L<<3,
   COGL_PRIVATE_FEATURE_FOUR_CLIP_PLANES = 1L<<4,
-  COGL_PRIVATE_FEATURE_PBOS = 1L<<5
+  COGL_PRIVATE_FEATURE_PBOS = 1L<<5,
+  COGL_PRIVATE_FEATURE_VBOS = 1L<<6
 } CoglPrivateFeatureFlags;
 
 /* Sometimes when evaluating pipelines, either during comparisons or

cogl/cogl-journal.c

@@ -1118,10 +1118,12 @@ create_attribute_buffer (CoglJournal *journal,
 {
   CoglAttributeBuffer *vbo;
 
+  _COGL_GET_CONTEXT (ctx, NULL);
+
   /* If CoglBuffers are being emulated with malloc then there's not
      really any point in using the pool so we'll just allocate the
      buffer directly */
-  if (!cogl_features_available (COGL_FEATURE_VBOS))
+  if (!(ctx->private_feature_flags & COGL_PRIVATE_FEATURE_VBOS))
     return cogl_attribute_buffer_new (n_bytes, NULL);
 
   vbo = journal->vbo_pool[journal->next_vbo_in_pool];

cogl/driver/gl/cogl-gl.c

@@ -213,9 +213,11 @@ _cogl_gl_update_features (CoglContext *context,
     flags |= COGL_FEATURE_SHADERS_GLSL;
 
   if (context->glGenBuffers)
-    flags |= (COGL_FEATURE_VBOS |
-              COGL_FEATURE_MAP_BUFFER_FOR_READ |
-              COGL_FEATURE_MAP_BUFFER_FOR_WRITE);
+    {
+      private_flags |= COGL_PRIVATE_FEATURE_VBOS;
+      flags |= (COGL_FEATURE_MAP_BUFFER_FOR_READ |
+                COGL_FEATURE_MAP_BUFFER_FOR_WRITE);
+    }
 
   if (_cogl_check_extension ("GL_ARB_texture_rectangle", gl_extensions))
     flags |= COGL_FEATURE_TEXTURE_RECTANGLE;

cogl/driver/gles/cogl-gles.c

@@ -91,7 +91,7 @@ _cogl_gles_update_features (CoglContext *context,
       flags |= COGL_FEATURE_DEPTH_RANGE;
     }
 
-  flags |= COGL_FEATURE_VBOS;
+  private_flags |= COGL_PRIVATE_FEATURE_VBOS;
 
   /* Both GLES 1.1 and GLES 2.0 support point sprites in core */
   flags |= COGL_FEATURE_POINT_SPRITE;