/* ColoredSingleChannelAnaglyphShader.frag.txt
 *
 * A more complex conversion shader for color anaglyphs than the one
 * hard-wired into PTBs Screen command. Applies full 3x3 color gain
 * matrix to color of one view channel, then optionally applies
 * gamma correction to the red output channel.
 *
 * Standard anaglyph conversion is implemented by the default shader in
 * Screen() and can be parameterized by SetAnaglyphStereoParameters.
 *
 * This shader is used for more complex/exotic ways of anaglyph conversion.
 *
 * Loaded/initialized by PsychColorCorrection.m as part of
 * the PTB imaging pipeline color anaglyph shading support.
 * Parameterized by SetAnaglyphStereoParameters.
 *
 * (C) 2012 Mario Kleiner - Released to you under MIT license.
 */

/* 3 by 3 color gain matrices, always denoted GainsLeft, even for right channel: */
uniform mat3 GainsLeft;

/* Gamma value for red out channel - Set zero for no gamma correction! */
uniform float RedGamma;

vec4 icmTransformColor(vec4 incolor)
{
    vec4 outcolor;

    /* Multiply first 3 vector components with matrix: */
    outcolor.rgb = GainsLeft * incolor.rgb;

    /* Alpha is passed through unmodified: */
    outcolor.a = incolor.a;

    /* Apply gamma correction to red channel, if requested: */
    /* Note: This op is expensive on GPUs without dynamic flow control! */
    if (RedGamma > 0.0) outcolor.r = pow(outcolor.r, RedGamma);

    return(outcolor);
}