fix

app.js

@@ -18,6 +18,57 @@ void main() {
 }`;
 
 const presetShaders = [
+  {
+    name: "Alien Core (Ported)",
+    code: `vec3 paletteAC(float d) {
+  return mix(vec3(0.2, 0.7, 0.9), vec3(1.0, 0.0, 1.0), d);
+}
+
+vec2 rotateAC(vec2 p, float a) {
+  float c = cos(a);
+  float s = sin(a);
+  return mat2(c, -s, s, c) * p;
+}
+
+float mapAC(vec3 p) {
+  for (int i = 0; i < 8; i++) {
+    float t = iTime * 0.2;
+    p.xz = rotateAC(p.xz, t);
+    p.xy = rotateAC(p.xy, t * 1.89);
+    p.xz = abs(p.xz) - 0.5;
+  }
+  return dot(sign(p), p) / 5.0;
+}
+
+vec4 raymarchAC(vec3 ro, vec3 rd) {
+  float t = 0.0;
+  vec3 col = vec3(0.0);
+  float d = 0.0;
+  for (int i = 0; i < 64; i++) {
+    vec3 p = ro + rd * t;
+    d = mapAC(p) * 0.5;
+    if (d < 0.02 || d > 100.0) break;
+    col += paletteAC(length(p) * 0.1) / (400.0 * d);
+    t += d;
+  }
+  float alpha = 1.0 / (max(d, 0.0001) * 100.0);
+  return vec4(col, alpha);
+}
+
+void mainImage(out vec4 fragColor, in vec2 fragCoord) {
+  vec2 uv = (fragCoord - 0.5 * iResolution.xy) / iResolution.x;
+  vec3 ro = vec3(0.0, 0.0, -50.0);
+  ro.xz = rotateAC(ro.xz, iTime);
+
+  vec3 cf = normalize(-ro);
+  vec3 cs = normalize(cross(cf, vec3(0.0, 1.0, 0.0)));
+  vec3 cu = normalize(cross(cf, cs));
+  vec3 uuv = ro + cf * 3.0 + uv.x * cs + uv.y * cu;
+  vec3 rd = normalize(uuv - ro);
+
+  fragColor = raymarchAC(ro, rd);
+}`,
+  },
   {
     name: "Neon Flow",
     code: `void mainImage(out vec4 fragColor, in vec2 fragCoord) {