clouds: lower deck and fade near-camera cloud clipping

config.js

@@ -321,8 +321,12 @@ window.CONFIG = {
     // altitude so aircraft fly above the deck.
     clouds: {
         enabled: true,            // false removes the volumetric cloud deck
-        top: 1.0,                 // ~12.9 km
+        top: 0.78,                // ~10.1 km, lower deck keeps camera clearance
         bottom: -0.2,             // ~-2.6 km (deck base slightly below terrain)
+        nearFade: {
+            start: 0.35,          // world units: clouds fade out very close to camera
+            end: 2.5              // full density from this distance onward
+        },
         // Coverage per weather level, 0 = clear, 1 = overcast. Only the
         // levels listed here override the built-in defaults
         // (sunny 0.20, cloudy 0.70, stormy 0.80, night 0.45). Live weather
@@ -344,6 +348,7 @@ window.CONFIG = {
             // wind: { speedScale: 140, maxSpeed: 0.12 } // very visible motion
         }
         // density: { sunny: 0.05, cloudy: 0.9, rain: 0.95, snow: 0.85, stormy: 1.0 }
+        // top: 0.65, nearFade: { start: 0.5, end: 3.5 }
     },
 
     // ------------------------------------------------------------------

vendor/clouds3d.js

@@ -77,6 +77,8 @@ var FRAG_SRC = [
     'uniform float uSunAlt;',
     'uniform float uCloudTop;',    // cloud deck upper edge (world Y)
     'uniform float uCloudBot;',    // cloud deck lower edge (world Y)
+    'uniform float uCloudNearFadeStart;',
+    'uniform float uCloudNearFadeEnd;',
     'uniform sampler2D uElev;',    // terrarium RGB height grid, same UV as uGround
     'uniform float uElevOn;',      // terrain enabled (0/1)
     'uniform float uElevScale;',   // metres -> world units (incl. exaggeration)
@@ -722,7 +724,8 @@ var FRAG_SRC = [
                     'vec3 ambC = albC * max(vec3(uSkyAmb), uStarAmb * vec3(0.7, 0.85, 1.0)) * 1.7;',
                     'vec3 moonC = albC * uMoonColor * (0.35 + 0.65 * max(0.0, dot(rd, uMoonDir))) * uMoonInt * 3.0;',
                     'vec3 cloudCol = direct + ambC + moonC;',
-                    'float alpha = clamp(d * stepSize * 3.50 * densityGain, 0.0, 1.0);',
+                    'float nearFade = smoothstep(uCloudNearFadeStart, uCloudNearFadeEnd, t);',
+                    'float alpha = clamp(d * stepSize * 3.50 * densityGain * nearFade, 0.0, 1.0);',
                     'cloudSum += cloudCol * alpha * trans;',
                     'trans *= (1.0 - alpha);',
                     'if (trans < 0.04) break;',
@@ -1296,6 +1299,8 @@ function init(canvas) {
         uSpeed: uSpeed, uDensity: uDensity, uDayProgress: uDayProgress,
         uSunAlt: uSunAlt,
         uCloudTop: uCloudTop, uCloudBot: uCloudBot,
+        uCloudNearFadeStart: gl.getUniformLocation(prog, 'uCloudNearFadeStart'),
+        uCloudNearFadeEnd: gl.getUniformLocation(prog, 'uCloudNearFadeEnd'),
         uElev: uElev, uElevOn: uElevOn, uElevScale: uElevScale, uTerrainExag: uTerrainExag,
         uSunDir: uSunDir, uMoonDir: uMoonDir, uMode: uMode,
         uAtmoModelOn: uAtmoModelOn, uAtmoHeightUnits: uAtmoHeightUnits,
@@ -1487,6 +1492,9 @@ if (window.CONFIG && window.CONFIG.clouds) {
 }
 CLOUD_TOP = Math.max(0.2, Math.min(CLOUD_TOP, 2.0));
 CLOUD_BOT = Math.min(CLOUD_BOT, CLOUD_TOP - 0.4);
+var CLOUD_NEAR_FADE_CFG = (window.CONFIG && window.CONFIG.clouds && window.CONFIG.clouds.nearFade) || {};
+var CLOUD_NEAR_FADE_START = (typeof CLOUD_NEAR_FADE_CFG.start === 'number') ? Math.max(0, CLOUD_NEAR_FADE_CFG.start) : 0.35;
+var CLOUD_NEAR_FADE_END = Math.max(CLOUD_NEAR_FADE_START + 0.1, (typeof CLOUD_NEAR_FADE_CFG.end === 'number') ? CLOUD_NEAR_FADE_CFG.end : 2.5);
 var CLOUDS_ON = !(window.CONFIG && window.CONFIG.clouds && window.CONFIG.clouds.enabled === false);
 var CLOUD_WIND_CFG = (window.CONFIG && window.CONFIG.clouds && window.CONFIG.clouds.wind) || {};
 var CLOUD_WIND_SCALE = (typeof CLOUD_WIND_CFG.speedScale === 'number') ? Math.max(0, CLOUD_WIND_CFG.speedScale) : 80;
@@ -7355,6 +7363,8 @@ window.clouds3dRender = function(target) {
     gl.uniform1f(s.uSpeed, speed);
     gl.uniform1f(s.uCloudTop, CLOUD_TOP);
     gl.uniform1f(s.uCloudBot, CLOUD_BOT);
+    gl.uniform1f(s.uCloudNearFadeStart, CLOUD_NEAR_FADE_START);
+    gl.uniform1f(s.uCloudNearFadeEnd, CLOUD_NEAR_FADE_END);
 
     // Ground mosaic uniforms + periodic re-fetch trigger.
     // uGroundCenter is the world position (X, Z) of the centre tile's