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/* Shader for applying a bias and scale factor to a rectangle texture during drawing.
* Can be used to apply f(g)=(g + prescaleoffset)*scalefactor + postscaleoffset;
* (w)2006 by Mario Kleiner. Licensed under MIT license.
*/
#extension GL_ARB_texture_rectangle : enable
/* We currently only support rectangular textures: */
uniform sampler2DRect Image;
uniform float prescaleoffset;
uniform float postscaleoffset;
uniform float scalefactor;
void main()
{
vec4 incolor = texture2DRect(Image, gl_TexCoord[0].st);
/* Just pass-through the alpha value, do not modify it: */
gl_FragColor.a = incolor.a;
/* Apply mapping to RGB channels... */
gl_FragColor.rgb = ((incolor.rgb + vec3(prescaleoffset)) * scalefactor) + vec3(postscaleoffset);
}
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