src/yuv2rgb_3.glslf

/*
 * Copyright 2010, Google Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * This is a planar YUV to RGB conversion shader that uses separate samplers to
 * hold Y, U and V components.
 */

uniform sampler2D ySampler;
uniform sampler2D uSampler;
uniform sampler2D vSampler;

#if defined (USE_UNIFORM_MATRIX)
uniform mat4 conversion;
#endif

varying vec2 yPlane;
varying vec2 uvPlane;

void main() {
  float yChannel = texture2D(ySampler, yPlane).r;
  float uChannel = texture2D(uSampler, uvPlane).r;
  float vChannel = texture2D(vSampler, uvPlane).r;
  /*
   * This does the colorspace conversion from Y'UV to RGB as a matrix
   * multiply.  It also does the offset of the U and V channels from
   * [0,1] to [-.5,.5] as part of the transform.
   */

  vec4 channels = vec4(yChannel, uChannel, vChannel, 1.0);

#if !defined(USE_UNIFORM_MATRIX)
  mat4 conversion = mat4(
        1.0,    1.0,    1.0,   0.0,
        0.0,   -0.344,  1.772, 0.0,
        1.402, -0.714,  0.0,   0.0,
        -0.701,  0.529, -0.886, 1.0
  );
#endif
  gl_FragColor = conversion * channels;
}