/usr/share/psychtoolbox-3/PsychOpenGL/PsychGLSLShaders/SphereProjectionShader.frag.txt is in psychtoolbox-3-common 3.0.11.20131230.dfsg1-1build1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 | /* Shader for application of a spherical projection of textures during drawing.
*
* (C)2010-2011 by Ingmar Schneider and Mario Kleiner.
* Licensed to you under MIT license.
*
* This is version 2, with improved math by Ingmar Schneider to fix the
* problems with central magnification and anisotropy.
*
*/
#extension GL_ARB_texture_rectangle : enable
uniform int doFilter;
uniform sampler2DRect Image;
uniform vec2 inSize;
uniform vec2 inOffset;
uniform vec2 outSize;
/* Width of the projection area at a distance R in cm */
uniform float Wflat;
/* Radius of the used spherical screen in cm */
uniform float R;
void main()
{
vec4 texcolor, tl, tr, bl, br;
/* Get wanted output pixel coordinates for which we should remap: */
/* texoutpos is the location of the output pixel for which we need */
/* to compute the final remapped color value */
vec2 texoutpos = (gl_TexCoord[0].st) - vec2(0.5, 0.5);
/* Apply 2D offset to output pixel location, as well as a 2D rescaling: */
/* This to account for situations where not the full display area of */
/* display device is used. */
texoutpos = clamp(texoutpos, vec2(0.0), outSize);
/* Geometric remapping/warping: Recompute and assign modified components */
/* of texoutpos, based on texinpos and display geometry: */
float Wunits = Wflat / R;
vec2 UnitsPerPixel = vec2(Wunits)/ outSize;
/* Centering */
texoutpos = (texoutpos - ((outSize+1.0)/2.0)) * UnitsPerPixel;
/* Unwarping */
texoutpos = texoutpos / sqrt(1.0 - pow(abs(texoutpos.x), 2.0) - pow(abs(texoutpos.y), 2.0));
/* Retransformation to image coordinates */
texoutpos = (texoutpos/UnitsPerPixel) + ((outSize+1.0)/2.0);
/* Offsetting */
vec2 texinpos = inOffset + texoutpos;
/* texinpos now contains the location of the final input image pixel to read */
/* for creation of the final output color pixel. This value may be fractional. */
/* Need to filter input image texture ourselves? */
if (doFilter > 0) {
/* Need to do our own bilinear filtering: Get colors of four nearest */
/* neighbour texels for given non-integral, fractional 'texinpos': */
tl=texture2DRect(Image, floor(texinpos));
tr=texture2DRect(Image, floor(texinpos) + vec2(1.0, 0.0));
bl=texture2DRect(Image, floor(texinpos) + vec2(0.0, 1.0));
br=texture2DRect(Image, floor(texinpos) + vec2(1.0, 1.0));
/* Perform weighted linear interpolation -- bilinear interpolation of the 4: */
tl=mix(tl,tr,fract(texinpos.x));
bl=mix(bl,br,fract(texinpos.x));
texcolor = mix(tl, bl, fract(texinpos.y));
}
else
{
/* Standard case: Hardware does bilinear filtering: */
texcolor = texture2DRect(Image, texinpos);
}
/* Set all undefined (outside input image) pixels to black background color. */
if (texinpos.x < 0.0 || texinpos.x >= inSize.x || texinpos.y < 0.0 || texinpos.y >= inSize.y || texinpos.x != texinpos.x || texinpos.y != texinpos.y) {
gl_FragColor = vec4(0.0);
}
else
{
/* Multiply filtered texcolor with incoming fragment color (GL_MODULATE emulation): */
/* Assign result as output fragment color: */
gl_FragColor = texcolor * gl_Color;
}
}
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