autotest/client/deps/glbench/yuv2rgb_4.glslf

/*
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 * modification, are permitted provided that the following conditions are
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 *
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 * 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
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 */

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

uniform sampler2D ySampler;
uniform sampler2D uvSampler; /* GL_LUMINANCE_ALPHA */

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

varying vec2 yPlane;
varying vec2 uvPlane;

void main() {
  float yChannel = texture2D(ySampler, yPlane).r;
  vec2 uvChannel = texture2D(uvSampler, uvPlane).ra;
  /*
   * 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, uvChannel, 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;
}