precision highp float; uniform float iTime; uniform vec2 iResolution; #define PIXEL_SIZE 3.0 bool getValue(float brightness, vec2 pos) { // do the simple math first if (brightness > 16.0/17.0) return false; if (brightness < 01.0/17.0) return true; vec2 pixel = floor(mod((pos.xy+0.5)/PIXEL_SIZE, 4.0)); int x = int(pixel.x); int y = int(pixel.y); bool result = false; // compute the 16 values by hand, store when it's a match if (x == 0 && y == 0) result = brightness < 16.0/17.0; else if (x == 2 && y == 2) result = brightness < 15.0/17.0; else if (x == 2 && y == 0) result = brightness < 14.0/17.0; else if (x == 0 && y == 2) result = brightness < 13.0/17.0; else if (x == 1 && y == 1) result = brightness < 12.0/17.0; else if (x == 3 && y == 3) result = brightness < 11.0/17.0; else if (x == 3 && y == 1) result = brightness < 10.0/17.0; else if (x == 1 && y == 3) result = brightness < 09.0/17.0; else if (x == 1 && y == 0) result = brightness < 08.0/17.0; else if (x == 3 && y == 2) result = brightness < 07.0/17.0; else if (x == 3 && y == 0) result = brightness < 06.0/17.0; else if (x == 0 && y == 1) result = brightness < 05.0/17.0; else if (x == 1 && y == 2) result = brightness < 04.0/17.0; else if (x == 2 && y == 3) result = brightness < 03.0/17.0; else if (x == 2 && y == 1) result = brightness < 02.0/17.0; else if (x == 0 && y == 3) result = brightness < 01.0/17.0; return result; } mat2 rot(in float a) { return mat2(cos(a),sin(a),-sin(a),cos(a)); } // main distance function float de(vec3 p) { float de = 0.0; float r = length(p); de += r - 5.0; de += (sin(p.x*p.y*p.z+iTime))*0.5; // de += (sin(p.x*p.y*4.0424+iTime * 1.9318)*1.0+.5)*0.01; return de; } // normal function vec3 normal(vec3 p) { vec3 e = vec3(0.0, 0.001, 0.0); return normalize(vec3( de(p+e.yxx)-de(p-e.yxx), de(p+e.xyx)-de(p-e.xyx), de(p+e.xxy)-de(p-e.xxy))); } void mainImage( out vec4 fragColor, in vec2 fragCoord ) { vec2 uv = fragCoord.xy / iResolution.xy * 2.0 - 1.0; uv.y *= iResolution.y / iResolution.x; vec3 from = vec3(-50, 0, 0); vec3 dir = normalize(vec3(uv*0.2, 1.0)); dir.xz *= rot(3.1415*.5); mat2 rotxz = rot(iTime*0.2); mat2 rotxy = rot(iTime*0.2); from.xy *= rotxy; from.xz *= rotxz; dir.xy *= rotxy; dir.xz *= rotxz; float mindist = 100000.0; float totdist = 0.0; bool set = false; vec3 norm = vec3(0); vec3 light = normalize(vec3(1.0, -3.0, 2.0)); for (int steps = 0 ; steps < 100 ; steps++) { if (set) continue; vec3 p = from + totdist * dir; float dist = max(min(de(p), 1.0), 0.0); mindist = min(dist, mindist); totdist += dist; if (dist < 0.01) { set = true; norm = normal(p); } } if (set) { fragColor = vec4(vec3(getValue( dot(light, norm)*.5+.5, fragCoord)), 1.0); } else { discard; } } void main() { mainImage(gl_FragColor, gl_FragCoord.xy); }

KEEGAN MCNAMARA