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varying vec4 v_position;
uniform vec2 u_resolution;
uniform float u_time;
uniform float u_mouse;
#define MAX_ITERATIONS 100
vec2 cmul(vec2 a, vec2 b) {
return vec2(a.x*b.x - a.y*b.y, a.x*b.y + a.y*b.x);
}
vec2 cdiv(vec2 a, vec2 b) {
float denominator = b.x*b.x + b.y*b.y;
if (denominator == 0.) return a;
return cmul(a, vec2(b.x, -b.y)) / denominator;
}
vec2 cpow(vec2 z, float n) {
float r = length(z);
float theta = atan(z.y, z.x);
return pow(r, n) * vec2(cos(n * theta), sin(n * theta));
}
void main() {
float time = mod(1.1 + mod(u_time * 1000.0, 100000.0) / 10000.0, 10.);
// float time = 2.0;
float ratio = u_resolution.x / u_resolution.y;
vec2 pos = v_position.xy/vec2(1.0, ratio);
vec2 z = 2.0 * (pos - vec2(0., 0.));
int i;
vec2 prevZ = z;
for (i = 0; i < MAX_ITERATIONS; i++) {
prevZ = z;
vec2 value = cpow(z, 3.0) + vec2(1., 0.);
vec2 value_der = 3.0 * cpow(z, 2.0);
z = z - time * cdiv(value, value_der);
if (length(z - prevZ) > 30.0) {
break;
}
}
gl_FragColor = vec4(0., 0., 0., 1.);
float diff = length(z - prevZ);
if (diff > 10.0) {
gl_FragColor = vec4(97., 42., 191., 255.0) / 255.;
} else if (diff > 1.0) {
gl_FragColor = vec4(150., 191., 69., 255.0) / 255.;
} else if (diff > 0.0) {
gl_FragColor = vec4(27., 14., 50., 255.0) / 255.;
}
}
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