Permanent above-clouds cruise + more structure

- Remove dive component from camY. Was mix(2.0, 1.2, diveT)
  (occasional dips into cloud top); now fixed at 2.2, always above
  the y=1.5 cloud ceiling. Cloud deck always visible below.
- WEATHER_DENSITY bumped again: sunny 0.55->0.65, cloudy 0.85->0.90,
  night 0.65->0.75. Even 'sunny' is now a partly-cloudy sky.
- clouds3d: third fBm detail layer at 3.2x frequency (was 2 layers).
  Contributions: base 1.0, mid 0.30, fine 0.12. Combined with the
  tighter smoothstep (0.18 -> 0.16) the silhouettes have wispier,
  more interesting edges instead of soft blobs.
- Same density bump in clouds2d for consistency.

vendor/clouds2d.js

@@ -122,10 +122,10 @@ function hex(rgb) {
 }
 
 var WEATHER_DENSITY = {
-    sunny: 0.55,
-    cloudy: 0.85,
+    sunny: 0.65,
+    cloudy: 0.90,
     stormy: 1.00,
-    night: 0.65
+    night: 0.75
 };
 
 // Load the noise image and upload it as a REPEAT-wrapped texture.

vendor/clouds3d.js

@@ -97,21 +97,23 @@ var FRAG_SRC = [
         '}',
         'return v;',
     '}',
-    // Density at a point in the cloud layer. Two fBm layers: the
-    // base one at low frequency gives the large puffs, the detail
-    // layer at higher frequency breaks up the silhouette so clouds
-    // don't look like soft blobs.
+    // Density at a point in the cloud layer. Three fBm layers: the
+    // base one at low frequency gives the large puffs, the mid
+    // detail layer breaks up the silhouette, the fine layer adds
+    // wispy edges. Combined the result has more visual interest than
+    // a single fBm.
     'float cloudDensity(vec3 p, float baseThresh) {',
         'float n = fbm3(p * 0.35 + vec3(0.0, 0.0, uTime * 0.06));',
         'float d = fbm3(p * 1.4 + vec3(uTime * 0.04, 7.3, uTime * 0.03));',
-        'n = n + d * 0.18;',
+        'float f = fbm3(p * 3.2 + vec3(2.1, uTime * 0.02, 5.7));',
+        'n = n + d * 0.30 + f * 0.12;',
         // Cloud layer thickness: between y=-0.3 (deck bottom)
         // and y=1.5 (top), densest in the middle.
         'float h = clamp((p.y + 0.3) / 1.8, 0.0, 1.0);',
         'float profile = 4.0 * h * (1.0 - h); // bell curve',
         'profile = max(profile, 0.0);',
         // Tighter smoothstep so the cloud edges have more detail.
-        'return smoothstep(baseThresh, baseThresh + 0.18, n) * profile;',
+        'return smoothstep(baseThresh, baseThresh + 0.16, n) * profile;',
     '}',
     // Star field: project ray onto a far sphere, hash-grid for
     // positions. Visible above the horizon at night with a small
@@ -129,16 +131,12 @@ var FRAG_SRC = [
     'void main() {',
         'vec2 uv = (gl_FragCoord.xy / uResolution.xy) * 2.0 - 1.0;',
         'uv.x *= uResolution.x / uResolution.y;',
-        // Camera path: slow drift in X, mostly cruising just above the
-        // cloud deck like an airliner cockpit. pow(...,n) shapes the
-        // sin into short dips so we occasionally skim the cloud top.
+        // Camera path: slow drift in X, cruising just above the cloud deck
+        // like an airliner cockpit. No dives — we stay above so the
+        // deck is always visible below us.
         'float drift = uTime * uSpeed * 0.45;',
-        // pow(...,8) keeps dives rare: most of the time diveT≈0,
-        // and only spikes briefly to 1.
-        'float diveT = pow(0.5 + 0.5 * sin(uTime * 0.10), 8.0);',
-        // Cruise at y=2.0 (just above cloud ceiling y=1.5), dive to
-        // y=1.2 — close enough to skim the cloud top, never deep inside.
-        'float camY = mix(2.0, 1.2, diveT);',
+        // Fixed altitude well above the cloud ceiling (y=1.5).
+        'float camY = 2.2;',
         'vec3 ro = vec3(drift, camY, drift * 0.7);',
         // Ray direction: nearly level, like looking out a cockpit
         // window. Horizon sits around the middle of the frame.
@@ -238,10 +236,10 @@ function hex(rgb) {
 // Higher density across the board so even 'sunny' shows some cloud
 // structure, not just clear sky. Same mapping as clouds2d.
 var WEATHER_DENSITY = {
-    sunny: 0.55,
-    cloudy: 0.85,
+    sunny: 0.65,
+    cloudy: 0.90,
     stormy: 1.00,
-    night: 0.65
+    night: 0.75
 };
 
 window.clouds3dRender = function(target) {