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/* Bits++_Mono++_FormattingShader.frag.txt -- Mono++ output formatter
*
* This shader converts a HDR texture into a RGBA8 8bpc framebuffer
* image, suitable for display with the CRS Bits++ system in Mono++
* mode. It expects the luminance image data in the red channel of
* the texture, with values ranging from 0.0 - 1.0, remaps it into
* the 16 bit data range of Bits++, then encodes the 16 bit luminance
* value into the red+green channels (8 MSB in red, 8 LSB in green). The
* blue channel is set to 0.0, i.e., black. The alpha channel is set to
* a fixed maximum value of 1.0, because alpha blending on such an image
* would be an undefined operation.
*
* This shader is intended for use as a plugin for the 'FinalOutputFormattingBlit'
* chain of the Psychtoolbox-3 imaging pipeline.
*
* (c)2007, 2008 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 luminance color conversion: */
float icmTransformColor1(float incolor);
/* Dynamically generated overlay color index lookup function: */
float getMonoOverlayIndex(vec2 pos);
void main()
{
/* Retrieve RGBA HDR input color value. */
float incolor = texture2DRect(Image, gl_TexCoord[0].st).r;
/* Apply some color transformation (clamping, gamma correction etc.): */
incolor = icmTransformColor1(incolor);
/* Remap red channel from 0.0 - 1.0 to 0 to 65535: */
float index = incolor * 65535.0 + 0.01;
/* Compute high byte (8 MSBs) and store in red output color. */
gl_FragColor.r = floor(index / 256.0) / 255.0;
/* Compute low byte (8 LSBs) and store in green output color. */
gl_FragColor.g = mod(index, 256.0) / 255.0;
/* Get blue channel value from overlay subfunction. */
gl_FragColor.b = getMonoOverlayIndex(gl_TexCoord[0].st);
/* Fix alpha channel to 1.0. */
gl_FragColor.a = 1.0;
}
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