auto-git:

[change] src/rendering/world-background-renderer.ts

src/rendering/world-background-renderer.ts

@@ -354,11 +354,78 @@ float fbm2(vec2 point) {
   return value;
 }
 
-float auroraFilamentPattern(vec2 point, float timeShift) {
-  float broad = abs(sin(point.x * 18.0 + noise2(point * 0.45) * 4.0 + timeShift));
-  float fine = abs(sin(point.x * 54.0 - point.y * 7.0 + noise2(point * 1.35) * 5.5 + timeShift * 1.8));
+float auroraRayPattern(vec2 uv, float timeShift, float phase) {
+  float field = fbm2(
+    vec2(
+      uv.x * 1.35 + phase + timeShift * 0.035,
+      uv.y * 0.55 - timeShift * 0.018
+    )
+  );
+  float slowFold =
+    0.5 +
+    0.5 *
+    sin(uv.x * 10.5 + field * 8.0 + phase + timeShift * 0.45);
+  float ribbonFold =
+    0.5 +
+    0.5 *
+    sin(uv.x * 21.0 + field * 12.0 - uv.y * 2.1 + timeShift * 0.78);
+  float filament =
+    0.5 +
+    0.5 *
+    sin(uv.x * 68.0 + field * 18.0 - uv.y * 5.5 + phase * 1.7 + timeShift * 1.18);
+  float gaps = smoothstep(
+    0.18,
+    0.92,
+    fbm2(vec2(uv.x * 2.5 - timeShift * 0.035 + phase, uv.y * 0.72 + 6.0))
+  );
 
-  return mix(pow(broad, 3.4), pow(fine, 5.6), 0.58);
+  return gaps *
+    (pow(slowFold, 2.2) * 0.58 +
+      pow(ribbonFold, 3.8) * 0.62 +
+      pow(filament, 11.0) * 1.45);
+}
+
+float auroraCurtain(
+  vec2 uv,
+  float skyY,
+  float center,
+  float width,
+  float timeShift,
+  float phase
+) {
+  float wave = fbm2(
+    vec2(
+      uv.x * 1.2 + phase + timeShift * 0.026,
+      uv.y * 0.9 - timeShift * 0.014
+    )
+  );
+  float foldedCenter =
+    center +
+    (wave - 0.5) * width * 1.55 +
+    sin(uv.x * 2.6 + phase + timeShift * 0.16) * width * 0.4;
+  float distanceToCenter = abs(skyY - foldedCenter);
+  float core = 1.0 - smoothstep(width * 0.08, width * 0.72, distanceToCenter);
+  float velvetGlow =
+    1.0 -
+    smoothstep(width * 0.65, width * 4.4, distanceToCenter);
+  float lowerCurtain =
+    smoothstep(foldedCenter - width * 5.6, foldedCenter - width * 0.18, skyY);
+  float upperCurtain =
+    1.0 -
+    smoothstep(foldedCenter + width * 1.45, foldedCenter + width * 3.9, skyY);
+  float verticalVeil = lowerCurtain * upperCurtain;
+  float rayPattern = auroraRayPattern(uv, timeShift, phase);
+  float taper =
+    1.0 -
+    smoothstep(
+      foldedCenter + width * 0.2,
+      foldedCenter + width * 3.6,
+      skyY
+    );
+
+  return (core * 1.22 + verticalVeil * 0.48 + velvetGlow * 0.18) *
+    rayPattern *
+    mix(0.68, 1.0, taper);
 }
 
 mat3 rotationY(float radians) {