clouds: reduce raymarch jitter and high-frequency boiling

vendor/clouds3d.js

@@ -186,16 +186,16 @@ var FRAG_SRC = [
         // The detail octave weighs at most 0.20 and fades to zero with
         // distance; past soft = 0.95 it contributes under 1 %, so the whole
         // 4-octave lookup is skipped for the (numerous) far samples.
-        'if (soft < 0.95) {',
+        'if (soft < 0.45) {',
-            'float d = fbm3(cp * 1.4 + vec3(uTime * 0.04, 7.3, uTime * 0.03));',
+            'float d = fbm3(cp * 1.15 + vec3(uTime * 0.04, 7.3, uTime * 0.03));',
-            'n = n + d * mix(0.20, 0.0, soft);',
+            'n = n + d * mix(0.12, 0.0, soft / 0.45);',
         '}',
         // Cloud layer between uCloudBot and uCloudTop, densest in the
         // middle (bell curve). The layer follows the Earth curvature.
         'float h = clamp((py - uCloudBot) / (uCloudTop - uCloudBot), 0.0, 1.0);',
         'float profile = 4.0 * h * (1.0 - h); // bell curve',
         'profile = max(profile, 0.0);',
-        'return smoothstep(baseThresh, baseThresh + 0.30 + soft * 0.25, n) * profile;',
+        'return smoothstep(baseThresh, baseThresh + 0.45 + soft * 0.35, n) * profile;',
     '}',
     // Star field: project ray onto a far sphere, hash-grid for
     // positions. Visible above the horizon at night with a small
@@ -498,13 +498,13 @@ var FRAG_SRC = [
         'float trans = 1.0;',
         'for (int i = 0; i < 24; i++) {',
             'vec3 p = ro + rd * t;',
-            'p.y += (ign(gl_FragCoord.xy + vec2(float(i) * 7.13, float(i) * 3.71)) - 0.5) * stepSize;',
+            'p.y += (ign(gl_FragCoord.xy + vec2(float(i) * 7.13, float(i) * 3.71)) - 0.5) * stepSize * 0.35;',
             'float py = p.y + earthDrop(p.xz);',
             'if (py > uCloudTop || py < uCloudBot - 0.1) break;',
             'if (tTerrain > 0.0 && t >= tTerrain) break;',
-            'float cSoft = smoothstep(7.0, 20.0, t);',
+            'float cSoft = smoothstep(3.0, 14.0, t);',
             'float d = cloudDensity(p, baseThresh, cSoft);',
-            'if (d > 0.005) {',
+            'if (d > 0.02) {',
                 'float lit = clamp((py - uCloudBot) / ((uCloudTop - uCloudBot) * 1.167), 0.0, 1.0);',
                 'vec3 cloudCol;',
                 'if (uPhysical > 0.5) {',
@@ -537,7 +537,7 @@ var FRAG_SRC = [
                     'cloudCol = mix(uCloudShadow, uCloud, lit);',
                     'cloudCol = mix(cloudCol, uLight, max(0.15, uDayProgress) * 0.35 * lit);',
                 '}',
-                'float alpha = clamp(d * stepSize * 0.9, 0.0, 1.0);',
+                'float alpha = clamp(d * stepSize * 1.15, 0.0, 1.0);',
                 'cloudSum += cloudCol * alpha * trans;',
                 'trans *= (1.0 - alpha);',
                 'if (trans < 0.04) break;',
@@ -702,14 +702,14 @@ var CLOUD_SAMPLER_GLSL = [
         // The detail octave weighs at most 0.20 and fades to zero with
         // distance; past soft = 0.95 it contributes under 1 %, so the whole
         // 4-octave lookup is skipped for the (numerous) far samples.
-        'if (soft < 0.95) {',
+        'if (soft < 0.45) {',
-            'float d = fbm3(cp * 1.4 + vec3(uTime * 0.04, 7.3, uTime * 0.03));',
+            'float d = fbm3(cp * 1.15 + vec3(uTime * 0.04, 7.3, uTime * 0.03));',
-            'n = n + d * mix(0.20, 0.0, soft);',
+            'n = n + d * mix(0.12, 0.0, soft / 0.45);',
         '}',
         'float h = clamp((py - uCloudBot) / (uCloudTop - uCloudBot), 0.0, 1.0);',
         'float profile = 4.0 * h * (1.0 - h);',
         'profile = max(profile, 0.0);',
-        'return smoothstep(baseThresh, baseThresh + 0.30 + soft * 0.25, n) * profile;',
+        'return smoothstep(baseThresh, baseThresh + 0.45 + soft * 0.35, n) * profile;',
     '}',
 ].join('\n');
 
@@ -808,7 +808,7 @@ var TERRAIN_FRAG_SRC = [
                     'float dens = 0.0;',
                     'for (int ci = 0; ci < 5; ci++) {',
                         'float tt = mix(tBot, tTop, (float(ci) + 0.5) / 5.0);',
-                        'dens += cloudDensity(vWorld + uSunDir * tt, baseTh, smoothstep(7.0, 20.0, tt));',
+                        'dens += cloudDensity(vWorld + uSunDir * tt, baseTh, smoothstep(3.0, 14.0, tt));',
                     '}',
                     'cShadow = mix(uCloudShadowFloor, 1.0,',
                         '    exp(-dens * uCloudShadowDensity));',