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/* DualPipeHDRPipe1_FormattingShader.frag.txt -- Low byte image output formatter
*
* This shader is intended for use as a plugin for the 'FinalOutputFormattingBlit1'
* chain of the Psychtoolbox-3 imaging pipeline.
*
* (c)2009 by Mario Kleiner, part of PTB-3, licensed to you under MIT license.
* See file License.txt in the Psychtoolbox root folder for the license.
*
*/
#extension GL_ARB_texture_rectangle : enable
uniform sampler2DRect Image;
/* Declare external function for color conversion: */
vec4 icmTransformColor(vec4 incolor);
void main()
{
/* Get default texel read position (x,y): x is column, y is row of image. */
vec2 readpos = gl_FragCoord.xy;
/* Retrieve RGBA HDR input color value for pixel. */
vec4 incolor = texture2DRect(Image, readpos);
/* Apply some color transformation (clamping, gamma correction etc.): */
/* Not yet implemented: incolor = icmTransformColor(incolor); */
/* Remap all color channels from 0.0 - 1.0 to 0 to 65535: */
/* Perform rounding for non-integral numbers and add a small epsilon to take numeric roundoff into account: */
vec3 index = floor(incolor.rgb * 65535.0 + 0.5) + 0.01;
/* Compute low bytes (8 LSBs) for color components. */
vec3 lowbytes = mod(index, 256.0) / 255.0;
/* Output low byte into framebuffer pixel: */
gl_FragColor.rgb = lowbytes;
/* Fix alpha channel to 1.0. */
gl_FragColor.a = 1.0;
}
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