Adding YUVA support for enabling Alpha Playback

cc/shader.cc

Index: cc/shader.cc
diff --git a/cc/shader.cc b/cc/shader.cc
index 89474299e4fb1a569870a5014feef9f7056f36a3..dda19c5f991b65f26e32d5ba8a8b86091fa317df 100644
--- a/cc/shader.cc
+++ b/cc/shader.cc
@@ -892,6 +892,71 @@ std::string FragmentShaderYUVVideo::getShaderString() const
     );
 }
 
+FragmentShaderYUVAVideo::FragmentShaderYUVAVideo()
+    : m_yTextureLocation(-1)
+    , m_uTextureLocation(-1)
+    , m_vTextureLocation(-1)
+    , m_aTextureLocation(-1)
+    , m_alphaLocation(-1)
+    , m_yuvMatrixLocation(-1)
+    , m_yuvAdjLocation(-1)
+{
+}
+
+void FragmentShaderYUVAVideo::init(WebGraphicsContext3D* context, unsigned program, bool usingBindUniform, int* baseUniformIndex)
+{
+    static const char* shaderUniforms[] = {
+        "y_texture",
+        "u_texture",
+        "v_texture",
+        "a_texture",
+        "alpha",
+        "cc_matrix",
+        "yuv_adj",
+    };
+    int locations[7];
+
+    getProgramUniformLocations(context, program, shaderUniforms, arraysize(shaderUniforms), arraysize(locations), locations, usingBindUniform, baseUniformIndex);
+
+    m_yTextureLocation = locations[0];
+    m_uTextureLocation = locations[1];
+    m_vTextureLocation = locations[2];
+    m_aTextureLocation = locations[3];
+    m_alphaLocation = locations[4];
+    m_yuvMatrixLocation = locations[5];
+    m_yuvAdjLocation = locations[6];
+
+    DCHECK(m_yTextureLocation != -1 && m_uTextureLocation != -1 && m_vTextureLocation != -1 && m_aTextureLocation != -1
+           && m_alphaLocation != -1 && m_yuvMatrixLocation != -1 && m_yuvAdjLocation != -1);
+}
+
+std::string FragmentShaderYUVAVideo::getShaderString() const
+{
+    return SHADER(
+        precision mediump float;
+        precision mediump int;
+        varying vec2 y_texCoord;
+        varying vec2 uv_texCoord;
+        uniform sampler2D y_texture;
+        uniform sampler2D u_texture;
+        uniform sampler2D v_texture;
+        uniform sampler2D a_texture;
+        uniform float alpha;
+        uniform vec3 yuv_adj;
+        uniform mat3 cc_matrix;
+        void main()
+        {
+            float y_raw = texture2D(y_texture, y_texCoord).x;
+            float u_unsigned = texture2D(u_texture, uv_texCoord).x;
+            float v_unsigned = texture2D(v_texture, uv_texCoord).x;
+            float a_raw = texture2D(a_texture, y_texCoord).x;
+            vec3 yuv = vec3(y_raw, u_unsigned, v_unsigned)  yuv_adj;
+            vec3 rgb = cc_matrix * yuv;
+            gl_FragColor = vec4(rgb, float(1)) * (a_raw * alpha);
+        }
+    );
+}
+
 FragmentShaderColor::FragmentShaderColor()
     : m_colorLocation(-1)
 {