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/* RGBMultiLUTLookupCombine_FormattingShader.frag.txt
*
* Remaps a RGB color texel from an input image by:
* 1. Rescaling each color channels input value via a multiplicator.
* 2. Rounding the rescaled value to an integer lookup index.
* 3. Looking up a RGBA8 bias value texel from a lookup table. For
* each color channel, an individual RGBA bias is looked up
* from an individual row of the CLUT texture.
* 4. Add the per channel biases up (== binary OR of biases) to
* form the final merged RGBA8 output pixel.
*
* This shader is useful for RGB high precision output devices with
* a per color channel bit-depth of up to 2^bpc <= maxtexturesize,
* i.e., constrained by maximum width of a texture:
* Up to 12 bpc on pre Direct3D-10 style hardware (max = 4096).
* Up to 13 bpc on Radeon HD2xxx/3xxxx/4xxx and Geforce 8xxx/9xxx hw.
*
* The shader is currently used by:
*
* - Native 10 bpc framebuffer of ATI Radeon X1000/HD2xxx/.... hardware.
* See "PsychHelperCreateARGB2101010RemapCLUT.m" for setup code etc.
*
* (w)2008 by Mario Kleiner. Licensed under MIT license.
*/
#extension GL_ARB_texture_rectangle : enable
uniform sampler2DRect Image;
uniform sampler2DRect CLUT;
uniform float Prescale;
void main()
{
/* Read input RGB pixel values in range 0.0 - 1.0: */
vec3 incolor = texture2DRect(Image, gl_TexCoord[0].st).rgb;
/* Remap them to integer index in resolution range: */
incolor = floor(incolor * Prescale + 0.5) + 0.5;
/* Lookup biases to apply for channels in rows of texture: */
vec4 rcomp = texture2DRect(CLUT, vec2(incolor.r, 0.5));
vec4 gcomp = texture2DRect(CLUT, vec2(incolor.g, 1.5));
vec4 bcomp = texture2DRect(CLUT, vec2(incolor.b, 2.5));
/* Combine biases to a single RGBA8 output pixel color: */
gl_FragColor = rcomp + gcomp + bcomp;
}
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