contrails: add jagged edges and restore 5 minute lifetime

config.js

@@ -206,7 +206,7 @@ window.CONFIG = {
         // above contrailStartKm, visible for contrailLifeS seconds.
         contrailChance: 1.00,
         contrailStartKm: 4,
-        contrailLifeS: 600,
+        contrailLifeS: 300,
         contrailWidthM: 1400,     // full trail width
         contrailFadeKm: 300,      // fully faded at this distance (ramp starts at 35 %)
         // Night contrast: a physically scaled contrail is a faint grey thread

vendor/clouds3d.js

@@ -5435,11 +5435,23 @@ var CT2_FRAG_SRC = [
     'varying float vV;',
     'varying float vS;',
     'varying vec3 vWorld;',
+    'float hash1(float x) {',
+        'return fract(sin(x * 127.1) * 43758.5453);',
+    '}',
+    'float noise1(float x) {',
+        'float i = floor(x);',
+        'float f = fract(x);',
+        'return mix(hash1(i), hash1(i + 1.0), f);',
+    '}',
     'void main() {',
         'float side = abs(vV);',
-        'float edge = 1.0 - smoothstep(0.25, 1.0, side);',
+        'float wob = 0.48 + 0.42 * noise1(vU * 24.0);',
-        'float head = 0.35 + 0.65 * vU;',
+        'float jag = noise1(vU * 61.0 + vV * 17.0) - 0.5;',
-        'float a = clamp(vS * edge * head, 0.0, 0.85);',
+        'float edge = 1.0 - smoothstep(wob * 0.16, wob, side + jag * 0.18);',
+        'edge *= 0.42 + 0.58 * pow(vU, 0.65);',
+        'float dens = 0.58 + 0.42 * noise1(vU * 31.0);',
+        'float head = 0.32 + 0.68 * vU;',
+        'float a = clamp(vS * edge * head * dens, 0.0, 0.88);',
         'if (a <= 0.004) discard;',
         'vec3 dayCol = vec3(1.0, 1.0, 1.0);',
         'vec3 nightCol = vec3(0.45, 0.55, 0.75);',