Swirly Circle
#define PI 3.1415926
// From https://andreashackel.de/tech-art/stripes-shader-2/
vec2 rotatePoint(in vec2 pt, in vec2 center, in float angle) {
float sinAngle = sin(angle);
float cosAngle = cos(angle);
pt -= center;
vec2 r = vec2(pt.x * cosAngle - pt.y * sinAngle, pt.x * sinAngle + pt.y * cosAngle);
r += center;
return r;
}
void main() {
vec2 uv = gl_FragCoord.xy / u_resolution;
float circle = length(uv - 0.5);
vec3 col = vec3(1.);
vec2 pos = rotatePoint(uv.xy, vec2(0.5, 0.5), u_time + sin(u_time) * circle * 2. * PI);
float p = mix(pos.x, pos.y, 0.5) * 10.;
col = vec3(floor(fract(p) + 0.5));
gl_FragColor = vec4(col, 1.);
}
Based on
andreashackel's rotate point