feat: mandelbrot + newton fractals

1 files changed, 55 insertions, 0 deletions

diff --git a/sketches/01/mandelbrot.frag b/sketches/01/mandelbrot.frag
new file mode 100644
index 0000000..689f2a4
--- /dev/null
+++ b/sketches/01/mandelbrot.frag
@@ -0,0 +1,55 @@
+varying vec4 v_position;
+uniform vec2 u_resolution;
+uniform float u_time;
+uniform float u_mouse;
+
+#define MAX_ITERATIONS 100
+
+vec2 cdiv(vec2 a, vec2 b) {
+  float r = length(b);
+  float theta = atan(b.y, b.x);
+  return vec2(cos(theta), sin(theta)) * (dot(a, b) / (r * r));
+}
+
+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 = 1.1 + mod(u_time * 1000.0, 100000.0) / 10000.0;
+  // float time = 4.0;
+
+  float ratio = u_resolution.x / u_resolution.y;
+  vec2 pos = v_position.xy/vec2(1.0, ratio);
+
+  vec2 c = 2.0 * (pos - vec2(0.0, 0.0));
+  vec2 z = vec2(0.0, 0.0);
+  int i;
+
+  vec2 prevZ = z;
+  for (i = 0; i < MAX_ITERATIONS; i++) {
+    prevZ = z;
+    z = cpow(z, time) + c;
+
+    if (length(z - prevZ) > 10.0) {
+      break;
+    }
+  }
+
+  if (i == MAX_ITERATIONS) {
+    gl_FragColor = vec4(27., 14., 50., 255.0) / 255.;
+  } else if (i > 5) {
+    gl_FragColor = vec4(97., 42., 191., 255.0) / 255.;
+  } else if (i > 4) {
+    gl_FragColor = vec4(150., 191., 69., 255.0) / 255.;
+  } else if (i > 3) {
+    gl_FragColor = vec4(230., 123., 40., 255.0) / 255.;
+  } else if (i > 2) {
+    gl_FragColor = vec4(27., 14., 50., 255.0) / 255.;
+  } else {
+    gl_FragColor = vec4(0., 0., 0., 1.);
+  }
+}
+