port of Daniel Piker's transform to GLSL port of https://gist.github.com/Dan-Piker/f7d790b3967d41bff8b0291f4cf7bd9e
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/** | |
original code https://gist.github.com/Dan-Piker/f7d790b3967d41bff8b0291f4cf7bd9e | |
need to declare the following: | |
uniform vec3 origin; | |
uniform float p; | |
uniform float q; | |
uniform float t; | |
*/ | |
vec3 pos = position - origin; | |
float xa = pos.x; | |
float ya = pos.y; | |
float za = pos.z; | |
//reverse stereographic projection to hypersphere | |
float pLength = (1. + xa * xa + ya * ya + za * za); | |
float xb = 2. * xa / pLength; | |
float yb = 2. * ya / pLength; | |
float zb = 2. * za / pLength; | |
float wb = (-1. + xa * xa + ya * ya + za * za) / pLength; | |
//rotate hypersphere by amount t | |
float xc = xb * cos(p * t) + yb * sin(p * t); | |
float yc = -xb * sin(p * t) + yb * cos(p * t); | |
float zc = zb * cos(q * t) - wb * sin(q * t); | |
float wc = zb * sin(q * t) + wb * cos(q * t); | |
//project stereographically back to flat 3D | |
float xd = xc / (1. - wc); | |
float yd = yc / (1. - wc); | |
float zd = zc / (1. - wc); | |
//the transformed point | |
vec3 transformed = vec3(xd, yd, zd); |
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