#version 330 out vec4 fragColor; uniform vec2 res; uniform float time; const float sharpness = 300; const float PI = 3.14159265358979323846; mat2 rot(float a) { return mat2( cos(a), -sin(a), sin(a), cos(a) ); } float square(vec2 m, float a, float r, vec2 p) { vec2 diff = abs((m - p) * rot(r)); float d = max(diff.x, diff.y); return clamp((a - d)*sharpness, 0.0, 1.0); } void main(void) { vec2 m = res/2; float s = min(m.x, m.y); vec2 p = (gl_FragCoord.xy - m) / s; float scene = 0; int n = 24; for (int i = 0; i < n; i++) { float c = square(vec2(0.5, 0) * rot(PI/2*(4.0*i/n)) * vec2(1, 1), 0.3, PI/2*(24.0*i/n - time/800), p); scene = abs(scene - c); } fragColor = vec4(vec3(1, 1, 1) * scene, 1); }