Texture Draw Calls Coalescing

cc/shader.cc

 // Copyright 2011 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 "cc/shader.h"
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 #include <public/WebGraphicsContext3D.h>
 
@@ skipping 141 matching lines @@
     m_matrixLocation = locations[0];
     m_texTransformLocation = locations[1];
     DCHECK(m_matrixLocation != -1 && m_texTransformLocation != -1);
 }
 
 std::string VertexShaderPosTexTransform::getShaderString() const
 {
     return SHADER(
         attribute vec4 a_position;
         attribute vec2 a_texCoord;
-        uniform mat4 matrix;
-        uniform vec4 texTransform;
+        attribute float a_index;

[shawnsingh, 2012/11/28 19:44:16]

If my prior comment about using the array of structs would work, then we could
make this an int.

+        uniform mat4 matrix[8];
+        uniform vec4 texTransform[8];
         varying vec2 v_texCoord;
         void main()
         {
-            gl_Position = matrix * a_position;
-            v_texCoord = a_texCoord * texTransform.zw + texTransform.xy;
+            gl_Position = matrix[int(a_index)] * a_position;
+            v_texCoord = a_texCoord * texTransform[int(a_index)].zw + texTransform[int(a_index)].xy;
         }
     );
 }
 
 VertexShaderQuad::VertexShaderQuad()
     : m_matrixLocation(-1)
     , m_pointLocation(-1)
 {
 }
 
@@ skipping 688 matching lines @@
             vec4 color2 = color;
             vec2 texCoord = clamp(v_texCoord, 0.0, 1.0) * texTransform.zw + texTransform.xy;
             vec2 coord = mod(floor(texCoord * frequency * 2.0), 2.0);
             float picker = abs(coord.x - coord.y);
             gl_FragColor = mix(color1, color2, picker) * alpha;
         }
     );
 }
 
 }  // namespace cc