Ensured that texture completeness takes into account base and max level

gpu/command_buffer/service/gles2_cmd_decoder.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "gpu/command_buffer/service/gles2_cmd_decoder.h"
 
 #include <stdio.h>
 
 #include <algorithm>
 #include <cmath>
@@ skipping 4981 matching lines @@
   LOCAL_COPY_REAL_GL_ERRORS_TO_WRAPPER("glGenerateMipmap");
   // Workaround for Mac driver bug. In the large scheme of things setting
   // glTexParamter twice for glGenerateMipmap is probably not a lage performance
   // hit so there's probably no need to make this conditional. The bug appears
   // to be that if the filtering mode is set to something that doesn't require
   // mipmaps for rendering, or is never set to something other than the default,
   // then glGenerateMipmap misbehaves.
   if (workarounds().set_texture_filter_before_generating_mipmap) {
     glTexParameteri(target, GL_TEXTURE_MIN_FILTER, GL_NEAREST_MIPMAP_NEAREST);
   }
+
+  // Workaround for Mac driver bug. If the base level is non-zero but the zero
+  // level of a texture has not been set glGenerateMipmaps sets the entire mip
+  // chain to opaque black. If the zero level is set at all, however, the mip
+  // chain is properly generated from the base level.
+  bool texture_zero_level_set = false;
+  GLenum type, internal_format, format;
+  if (workarounds().set_zero_level_before_generating_mipmap &&
+      target == GL_TEXTURE_2D) {
+    Texture* tex = texture_ref->texture();
+    if (tex && tex->base_level() != 0 &&
+        !tex->GetLevelType(target, 0, &type, &internal_format) &&
+        tex->GetLevelType(target, tex->base_level(), &type, &internal_format)) {

[zmo, 2015/11/23 23:14:47]

nit: the last condition is unnecessary because CanGenerateMipmaps() above should
already make sure it always returns true.

+      format = TextureManager::ExtractFormatFromStorageFormat(internal_format);
+      glTexImage2D(target, 0, internal_format, 1, 1, 0, format, type, nullptr);
+      texture_zero_level_set = true;
+    }
+  }
+
   glGenerateMipmapEXT(target);
+
+  if (texture_zero_level_set) {
+    glTexImage2D(target, 0, internal_format, 0, 0, 0, format, type, nullptr);

[zmo, 2015/11/23 23:14:47]

Could you please add a note that this might have side effects because the
texture level might have switched from uninitialized to initialized to size(0,
0) , but hopefully command buffer will intercept most calls that are affected?

+  }
+
   if (workarounds().set_texture_filter_before_generating_mipmap) {
     glTexParameteri(target, GL_TEXTURE_MIN_FILTER,
                     texture_ref->texture()->min_filter());
   }
   GLenum error = LOCAL_PEEK_GL_ERROR("glGenerateMipmap");
   if (error == GL_NO_ERROR) {
     texture_manager()->MarkMipmapsGenerated(texture_ref);
   }
 }
 
@@ skipping 10279 matching lines @@
   return error::kNoError;
 }
 
 // Include the auto-generated part of this file. We split this because it means
 // we can easily edit the non-auto generated parts right here in this file
 // instead of having to edit some template or the code generator.
 #include "gpu/command_buffer/service/gles2_cmd_decoder_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu