[Chromoting] Implement GlRenderer

remoting/client/gl_canvas.h

 // Copyright 2016 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.
 
 #ifndef REMOTING_CLIENT_OPENGL_GL_CANVAS_H_
 #define REMOTING_CLIENT_OPENGL_GL_CANVAS_H_
 
 #include <array>
 
 #include "base/macros.h"
@@ skipping 12 matching lines @@
 // with the origin at the upper-left corner of the canvas.
 class GlCanvas {
  public:
   // gl_version: version number of the OpenGL ES context. Either 2 or 3.
   GlCanvas(int gl_version);
 
   ~GlCanvas();
 
   // Sets the normalized transformation matrix. This matrix defines how the
   // canvas should be shown on the view.
-  // 3 by 3 transformation matrix, [ m0, m1, m2, m3, m4, m5, m6, m7, m8 ].
+  // 3 by 3 transformation matrix **in column-major order**, i. e.
+  // [ m0, m3, m6, m1, m4, m7, m2, m5, m8 ].
   // The matrix will be multiplied with the positions (with projective space,
   // (x, y, 1)) to draw the textures with the right zoom and pan configuration.
   //
   // | m0, m1, m2, |   | x |
   // | m3, m4, m5, | * | y |
   // | m6, m7, m8  |   | 1 |
   //
   // For a typical transformation matrix such that m1=m3=m6=m7=0 and m8=1, m0
   // and m4 defines the ratio of canvas width or height over view width or
   // height. m2 and m5 defines the offset of the upper-left corner in percentage
@@ skipping 36 matching lines @@
   GLuint tex_cord_location_;
 
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(GlCanvas);
 };
 
 }  // namespace remoting
 
 #endif  // REMOTING_CLIENT_OPENGL_GL_CANVAS_H_