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#version 430
layout(local_size_x = 1, local_size_y = 1) in;
#include <utils>
#define MAX_ITERATIONS 200
const float antialiasing = 0.28;
uniform float seconds = 0;
layout(rgba8) uniform writeonly image2D output_image;
float fabs(float a) {
return a > 0. ? a : -a;
}
float cosh(float val) {
float tmp = exp(val);
float cosH = (tmp + 1.0 / tmp) / 2.0;
return cosH;
}
float sinh(float val) {
float tmp = exp(val);
float sinH = (tmp - 1.0 / tmp) / 2.0;
return sinH;
}
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, int n) {
vec2 res = z;
for (int i = 0; i < 20; i++) {
if (i >= n - 1) break;
res = cmul(z, res);
}
return res;
}
vec2 cexp(vec2 z) {
return exp(z.x) * vec2(cos(z.y), sin(z.y));
}
vec2 get_step(vec2 z) {
vec2 value = cpow(z, 5) + 2.0 * cpow(z, 3) - vec2(1., 0.);
vec2 derivative = 5.0 * cpow(z, 4) + 3.0 * cpow(z, 2);
return cdiv(value, derivative);
}
vec3 image(vec2 uv) {
vec2 prevZ;
vec2 z = uv * 3.0;
float t = seconds / 20;
vec2 factor = vec2(mod(t + 0.1, 2), 0);
int iterations = 0;
for (int i = 0; i < MAX_ITERATIONS; i++) {
prevZ = z;
z = prevZ - cmul(factor, get_step(prevZ));
iterations++;
if (fabs(z.x - prevZ.x) < 0.001) break;
}
float val = float(iterations) * 10.0 / float(MAX_ITERATIONS);
float r = 0.1;
float g = min(val * 0.2, 0.7);
float b = min(val * 0.8, 0.7);
return srgb(r, g, b);
}
vec3 antialiased_image(vec2 uv) {
vec2 resolution = vec2(imageSize(output_image).xy);
float s = antialiasing / max(resolution.x, resolution.y);
vec3 sum = vec3(0);
int count = 0;
for (int i = -2; i < 2; i++)
for (int j = -2; j < 2; j++, count++)
sum += image(uv + vec2(i, j) * s);
return sum / count;
}
void main() {
vec2 resolution = vec2(imageSize(output_image).xy);
float aspect_ratio = resolution.y / resolution.x;
vec2 uv = (gl_GlobalInvocationID.xy - resolution * 0.5) * vec2(1.0, aspect_ratio) / resolution;
// vec3 color = image(uv);
vec3 color = antialiased_image(uv);
imageStore(output_image, ivec2(gl_GlobalInvocationID.xy), vec4(color, 1));
}
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