Reverse scene node drawing order.

mojo/services/gfx/composition/interfaces/nodes.mojom

 // Copyright 2015 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.
 
 // Primitives express the geometry of the scene, such as quads and references
 // to embedded scenes.  Primitives are arranged hierarchically as nodes,
 // each with an associated transformation matrix.
 
 [DartPackage="mojo_services"]
 module mojo.gfx.composition;
 
 import "mojo/services/geometry/interfaces/geometry.mojom";
 import "mojo/services/gfx/composition/interfaces/hit_tests.mojom";
 
 // Nodes express the geometry and content of the scene, such as images and
 // references to embedded scenes.  Nodes are arranged to form a directed
 // acyclic graph of drawing commands.
 //
 // The node graph is processed in pre-order traversal.  Starting from the
-// root, the compositor applies the transformation, clip, recursively
-// processes the node's children according to the node's combinator rule,
-// then applies the node's own operation.
+// root, the compositor applies the transformation, clip, applies the
+// node's operation (if any), then recursively processes the node's children
+// according to the node's combinator rule.
 //
 // BLOCKED NODES
 //
 // Due to the asynchronous nature of the system, it may happen that some
 // nodes cannot be processed immediately at drawing time because they require
 // access to certain resources which are not available, such as a specific
 // version of a scene which has yet to be produced by some other application.
 //
 // When a node cannot be drawn due to an unsatisfied dependency, it is
 // said to be "blocked".  Blocked nodes prevent rendering of the entire
@@ skipping 175 matching lines @@
 };
 
 // Specifies how blending should take place.
 struct Blend {
   // The opacity for composition in a range from 0 (fully transparent)
   // to 255 (fully opaque).
   uint8 alpha = 255;
 
   // TODO(jeffbrown): Blend modes and texture filtering.
 };