More clouds + finer structure, switch default back to clouds3d

- WEATHER_DENSITY bumped: sunny 0.20->0.55, cloudy 0.70->0.85,
  night 0.45->0.65. Stormy stays at 1.0 (already maxed).
  Even 'sunny' now has visible cloud structure, not just clear sky.
- clouds3d: add a second fBm layer at 4x frequency for fine detail,
  blended at 18% into the base. Combined with the tighter smoothstep
  (0.24 -> 0.18) the cloud silhouettes have more interesting edges
  instead of soft blob shapes.
- Same density bump applied to clouds2d so swapping renderers
  doesn't change the visual weather.
- config.renderer: clouds2d -> clouds3d (user request)

config.js

@@ -46,7 +46,7 @@ window.CONFIG = {
     units: {
         temperature: 'C'
     },
-    renderer: 'clouds2d',  // 'vanta', 'clouds2d', or 'clouds3d'
+    renderer: 'clouds3d',  // 'vanta', 'clouds2d', or 'clouds3d'
     location: {
         // Latitude and longitude for sun/moon calculations
         // Default: Passau, Germany

vendor/clouds2d.js

@@ -122,10 +122,10 @@ function hex(rgb) {
 }
 
 var WEATHER_DENSITY = {
-    sunny: 0.20,
-    cloudy: 0.70,
+    sunny: 0.55,
+    cloudy: 0.85,
     stormy: 1.00,
-    night: 0.45
+    night: 0.65
 };
 
 // Load the noise image and upload it as a REPEAT-wrapped texture.

vendor/clouds3d.js

@@ -97,15 +97,21 @@ var FRAG_SRC = [
         '}',
         'return v;',
     '}',
-    // Density at a point in the cloud layer.
+    // 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.
     '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;',
         // 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);',
-        'return smoothstep(baseThresh, baseThresh + 0.24, n) * profile;',
+        // Tighter smoothstep so the cloud edges have more detail.
+        'return smoothstep(baseThresh, baseThresh + 0.18, n) * profile;',
     '}',
     // Star field: project ray onto a far sphere, hash-grid for
     // positions. Visible above the horizon at night with a small
@@ -229,13 +235,13 @@ function hex(rgb) {
             (rgb & 255) / 255];
 }
 
-// Same density mapping as clouds2d so swapping renderers doesn't
-// change the visual weather.
+// Higher density across the board so even 'sunny' shows some cloud
+// structure, not just clear sky. Same mapping as clouds2d.
 var WEATHER_DENSITY = {
-    sunny: 0.20,
-    cloudy: 0.70,
+    sunny: 0.55,
+    cloudy: 0.85,
     stormy: 1.00,
-    night: 0.45
+    night: 0.65
 };
 
 window.clouds3dRender = function(target) {