[mutter] cogl: Remove unused COGL_FEATURE_ID_DEPTH_TEXTURE

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit fb49e9def7bfcee0d5832f4d015e36993807745b
Author: Adam Jackson <ajax redhat com>
Date:   Thu Oct 17 19:35:35 2019 -0400

    cogl: Remove unused COGL_FEATURE_ID_DEPTH_TEXTURE
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/866

 cogl/cogl/cogl-context.h                    | 3 ---
 cogl/cogl/cogl-framebuffer.h                | 3 ---
 cogl/cogl/driver/gl/gl/cogl-driver-gl.c     | 6 ------
 cogl/cogl/driver/gl/gles/cogl-driver-gles.c | 5 -----
 4 files changed, 17 deletions(-)
---
diff --git a/cogl/cogl/cogl-context.h b/cogl/cogl/cogl-context.h
index 2f77960ee..f4fd7be57 100644
--- a/cogl/cogl/cogl-context.h
+++ b/cogl/cogl/cogl-context.h
@@ -194,8 +194,6 @@ cogl_is_context (void *object);
  * @COGL_FEATURE_ID_BUFFER_AGE: Available if the age of #CoglOnscreen back
  *    buffers are tracked and so cogl_onscreen_get_buffer_age() can be
  *    expected to return age values other than 0.
- * @COGL_FEATURE_ID_DEPTH_TEXTURE: Whether #CoglFramebuffer support rendering
- *     the depth buffer to a texture.
  * @COGL_FEATURE_ID_PRESENTATION_TIME: Whether frame presentation
  *    time stamps will be recorded in #CoglFrameInfo objects.
  *
@@ -213,7 +211,6 @@ typedef enum _CoglFeatureID
   COGL_FEATURE_ID_MAP_BUFFER_FOR_READ,
   COGL_FEATURE_ID_MAP_BUFFER_FOR_WRITE,
   COGL_FEATURE_ID_SWAP_BUFFERS_EVENT,
-  COGL_FEATURE_ID_DEPTH_TEXTURE,
   COGL_FEATURE_ID_PRESENTATION_TIME,
   COGL_FEATURE_ID_FENCE,
   COGL_FEATURE_ID_TEXTURE_RG,
diff --git a/cogl/cogl/cogl-framebuffer.h b/cogl/cogl/cogl-framebuffer.h
index 99ed6bde9..8fa313eea 100644
--- a/cogl/cogl/cogl-framebuffer.h
+++ b/cogl/cogl/cogl-framebuffer.h
@@ -846,9 +846,6 @@ cogl_framebuffer_set_stereo_mode (CoglFramebuffer *framebuffer,
  * is available as a texture. You can retrieve the texture with
  * cogl_framebuffer_get_depth_texture().
  *
- * <note>It's possible that your GPU does not support depth textures. You
- * should check the %COGL_FEATURE_ID_DEPTH_TEXTURE feature before using this
- * function.</note>
  * <note>It's not valid to call this function after the framebuffer has been
  * allocated as the creation of the depth texture is done at allocation time.
  * </note>
diff --git a/cogl/cogl/driver/gl/gl/cogl-driver-gl.c b/cogl/cogl/driver/gl/gl/cogl-driver-gl.c
index 327cf6fad..72ed61332 100644
--- a/cogl/cogl/driver/gl/gl/cogl-driver-gl.c
+++ b/cogl/cogl/driver/gl/gl/cogl-driver-gl.c
@@ -430,12 +430,6 @@ _cogl_driver_update_features (CoglContext *ctx,
                       COGL_FEATURE_ID_OFFSCREEN_MULTISAMPLE, TRUE);
     }
 
-  if (COGL_CHECK_GL_VERSION (gl_major, gl_minor, 3, 0) ||
-      _cogl_check_extension ("GL_ARB_depth_texture", gl_extensions))
-    {
-      COGL_FLAGS_SET (ctx->features, COGL_FEATURE_ID_DEPTH_TEXTURE, TRUE);
-    }
-
   COGL_FLAGS_SET (private_features, COGL_PRIVATE_FEATURE_PBOS, TRUE);
 
   flags |= (COGL_FEATURE_MAP_BUFFER_FOR_READ |
diff --git a/cogl/cogl/driver/gl/gles/cogl-driver-gles.c b/cogl/cogl/driver/gl/gles/cogl-driver-gles.c
index 12419a0fe..483f6f987 100644
--- a/cogl/cogl/driver/gl/gles/cogl-driver-gles.c
+++ b/cogl/cogl/driver/gl/gles/cogl-driver-gles.c
@@ -318,11 +318,6 @@ _cogl_driver_update_features (CoglContext *context,
                       COGL_FEATURE_ID_UNSIGNED_INT_INDICES, TRUE);
     }
 
-  if (_cogl_check_extension ("GL_OES_depth_texture", gl_extensions))
-    {
-      COGL_FLAGS_SET (context->features, COGL_FEATURE_ID_DEPTH_TEXTURE, TRUE);
-    }
-
   if (context->glMapBuffer)
     {
       /* The GL_OES_mapbuffer extension doesn't support mapping for