cogl: expose the semantic differences of gl/gles2 npot textures

This adds three new feature flags COGL_FEATURE_TEXTURE_NPOT_BASIC,
COGL_FEATURE_TEXTURE_NPOT_MIPMAP and COGL_FEATURE_TEXTURE_NPOT_REPEAT
that can tell you if your hardware supports non power of two textures,
npot textures + mipmaps and npot textures + wrap modes other than
CLAMP_TO_EDGE.

The pre-existing COGL_FEATURE_TEXTURE_NPOT feature implies all of the
above.

By default GLES 2 core supports npot textures but mipmaps and repeat
modes can only be used with power of two textures. This patch also makes
GLES check for the GL_OES_texture_npot extension to determine if mipmaps
and repeating are supported with npot textures.

cogl/cogl-types.h

@@ -219,7 +219,10 @@ typedef enum { /*< prefix=COGL_PIXEL_FORMAT >*/
 /**
  * CoglFeatureFlags:
  * @COGL_FEATURE_TEXTURE_RECTANGLE: ARB_texture_rectangle support
- * @COGL_FEATURE_TEXTURE_NPOT: ARB_texture_non_power_of_two support
+ * @COGL_FEATURE_TEXTURE_NPOT: Non power of two textures are supported
+ *    by the hardware. This is a equivalent to the
+ *    %COGL_FEATURE_TEXTURE_NPOT_BASIC, %COGL_FEATURE_TEXTURE_NPOT_MIPMAP
+ *    and %COGL_FEATURE_TEXTURE_NPOT_REPEAT features combined.
  * @COGL_FEATURE_TEXTURE_YUV: ycbcr conversion support
  * @COGL_FEATURE_TEXTURE_READ_PIXELS: glReadPixels() support
  * @COGL_FEATURE_SHADERS_GLSL: GLSL support
@@ -234,6 +237,17 @@ typedef enum { /*< prefix=COGL_PIXEL_FORMAT >*/
  *     %COGL_INDICES_TYPE_UNSIGNED_INT is supported in
  *     cogl_vertex_buffer_indices_new().
  * @COGL_FEATURE_DEPTH_RANGE: cogl_material_set_depth_range() support
+ * @COGL_FEATURE_TEXTURE_NPOT_BASIC: The hardware supports non power
+ *     of two textures, but you also need to check the
+ *     %COGL_FEATURE_TEXTURE_NPOT_MIPMAP and %COGL_FEATURE_TEXTURE_NPOT_REPEAT
+ *     features to know if the hardware supports npot texture mipmaps
+ *     or repeat modes other than
+ *     %COGL_MATERIAL_WRAP_MODE_CLAMP_TO_EDGE respectively.
+ * @COGL_FEATURE_TEXTURE_NPOT_MIPMAP: Mipmapping is supported in
+ *     conjuntion with non power of two textures.
+ * @COGL_FEATURE_TEXTURE_NPOT_REPEAT: Repeat modes other than
+ *     %COGL_MATERIAL_WRAP_MODE_CLAMP_TO_EDGE are supported by the
+ *     hardware.
  *
  * Flags for the supported features.
  *
@@ -254,7 +268,10 @@ typedef enum
   COGL_FEATURE_VBOS		      = (1 << 11),
   COGL_FEATURE_PBOS		      = (1 << 12),
   COGL_FEATURE_UNSIGNED_INT_INDICES   = (1 << 13),
-  COGL_FEATURE_DEPTH_RANGE            = (1 << 14)
+  COGL_FEATURE_DEPTH_RANGE            = (1 << 14),
+  COGL_FEATURE_TEXTURE_NPOT_BASIC     = (1 << 15),
+  COGL_FEATURE_TEXTURE_NPOT_MIPMAP    = (1 << 16),
+  COGL_FEATURE_TEXTURE_NPOT_REPEAT    = (1 << 17)
 } CoglFeatureFlags;
 
 /**

cogl/driver/gl/cogl.c

@@ -199,7 +199,10 @@ _cogl_features_init (void)
 #ifdef HAVE_CLUTTER_OSX
       if (really_enable_npot ())
 #endif
-        flags |= COGL_FEATURE_TEXTURE_NPOT;
+        flags |= COGL_FEATURE_TEXTURE_NPOT
+          | COGL_FEATURE_TEXTURE_NPOT_BASIC
+          | COGL_FEATURE_TEXTURE_NPOT_MIPMAP
+          | COGL_FEATURE_TEXTURE_NPOT_REPEAT;
     }
 
 #ifdef GL_YCBCR_MESA

cogl/driver/gles/cogl-feature-functions.h

@@ -80,3 +80,13 @@ COGL_FEATURE_BEGIN (element_index_uint, 255, 255,
                     COGL_FEATURE_UNSIGNED_INT_INDICES,
                     0)
 COGL_FEATURE_END ()
+
+COGL_FEATURE_BEGIN (texture_npot, 255, 255,
+                    "OES\0",
+                    "texture_npot\0",
+                    COGL_FEATURE_TEXTURE_NPOT |
+                    COGL_FEATURE_TEXTURE_NPOT_BASIC |
+                    COGL_FEATURE_TEXTURE_NPOT_MIPMAP |
+                    COGL_FEATURE_TEXTURE_NPOT_REPEAT,
+                    0)
+COGL_FEATURE_END ()

cogl/driver/gles/cogl.c

@@ -100,6 +100,9 @@ _cogl_features_init (void)
 
 #ifdef HAVE_COGL_GLES2
   flags |= COGL_FEATURE_SHADERS_GLSL | COGL_FEATURE_OFFSCREEN;
+  /* Note GLES 2 core doesn't support mipmaps for npot textures or
+   * repeat modes other than CLAMP_TO_EDGE. */
+  flags |= COGL_FEATURE_TEXTURE_NPOT_BASIC;
 #endif
 
   flags |= COGL_FEATURE_VBOS;