From 26bd5bbc5978279b7fa537afbbd11f5ced81b8b5 Mon Sep 17 00:00:00 2001
From: Richard Zink <Richard Zink>
Date: Sat, 10 Oct 2026 11:50:07 +0200
Subject: [PATCH] contrails: keep visible at night as dimmed moonlit streaks
 (42% of night ramp); city debug counter + pending-terrain log

---
 vendor/clouds3d.js | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/vendor/clouds3d.js b/vendor/clouds3d.js
index 16b3c09..8ba3549 100644
--- a/vendor/clouds3d.js
+++ b/vendor/clouds3d.js
@@ -2163,7 +2163,8 @@ function fetchSettlements() {
         if (!fresh && cityGeo) return;   // fully cached cycle - nothing changed
         cityGeo = list.slice();
         buildCityVBO(elevGl || (clouds3dState && clouds3dState.gl));
-        console.log('[clouds3d] settlements: ' + list.length + ' places -> ' + cityCount + ' lights');
+        console.log('[clouds3d] settlements: ' + list.length + ' places -> ' + cityCount + ' lights' +
+            (cityCount ? '' : ' (terrain pending)'));
     });
 }
 
@@ -2508,6 +2509,8 @@ function buildCityVBO(gl) {
     gl.bindBuffer(gl.ARRAY_BUFFER, vbo);
     gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(verts), gl.STATIC_DRAW);
     cityVbo = vbo; cityCount = verts.length / 5;
+    // debug counter (also used by headless smoke tests)
+    window.__cityDbg = { places: cityGeo ? cityGeo.length : 0, lights: cityCount };
     sanitizeCityAttribSlots(gl);
     if (!cityProg) {
         cityProg = makeProgram(gl, CITY_VERT_SRC, CITY_FRAG_SRC);
@@ -2850,8 +2853,9 @@ var planeV = null, planeVbo = null, planeProg = null, planeU = null, planeA = nu
 // ground distance in 8 curve segments and swept into a ribbon
 // (contrailWidthM wide). The fragment shader dissolves it into a cloud
 // stripe: density patches along the length, wavy eroded edges (per-trail
-// noise phase), alpha ramping up toward the head. Fades out with dayf
-// (dark exhaust is invisible anyway).
+// noise phase), alpha ramping up toward the head. By day the stripes are
+// sun-lit white; by night they stay visible as dimmed moonlit streaks
+// (reusing the car-lights night ramp), around 40 % strength.
 var ctBuf = null, ctVbo = null, ctVerts = 0;
 var ctProg = null, ctA = null, ctU = null;
 
@@ -3752,8 +3756,10 @@ window.clouds3dRender = function(target) {
         // Only CONFIG.flights.contrailChance of the aircraft leave a
         // persistent stripe (the ice-humidity window is not everywhere),
         // and the stripe follows the curved leg: walked backwards from
-        // the aircraft in fixed steps.
-        if (dayf > 0.02) {
+        // the aircraft in fixed steps. Visible by day (sun-lit) AND by
+        // night as dimmed moonlit streaks.
+        var tvis = Math.max(dayf, carNight * 0.42);
+        if (tvis > 0.02) {
             if (!ctBuf) ctBuf = new Float32Array(CT_MAX * CT_SEG * 6 * 7);
             ctVerts = 0;
             var _cs = { x: 0, z: 0, tx: 1, tz: 0 };