config.maxFps: scene frame-rate cap (default 30, 0 = free; motion stays time-based)

README.md

@@ -83,6 +83,7 @@ window.CONFIG = {
     units: { temperature: 'C' },       // 'C' | 'F'
     credits: true,                     // data-attribution block in info box
     renderScale: 1,                    // 0.3..1 internal 3D resolution
+    maxFps: 30,                        // WebGL scene frame cap (0 = free)
 
     location: {                        // drives scene anchor, sun/moon, weather
         lat: 51.5074,                  //   -90..+90, north positive

background.html

@@ -569,17 +569,28 @@ window.__flightDir = _pickDir('flight');
 window.__fetchDir  = _pickDir('fetch');
 
 // ---- WebGL scene (clouds3d.js) ------------------------------------------
+// CONFIG.maxFps caps the scene frame rate (default 30; 0 = free-running).
+// All scene animation is time-based (cloud drift, traffic, bobbing), so a
+// lower cap changes smoothness, never motion speed. The UI clock/theme
+// loop is untouched.
 var sceneEl = document.getElementById('scene');
 function sceneRender() {
     if (sceneEl && typeof window.clouds3dRender === 'function') {
         window.clouds3dRender(sceneEl);
     }
 }
+var _maxFps = (window.CONFIG && typeof window.CONFIG.maxFps === 'number')
+    ? window.CONFIG.maxFps : 30;
+var _frameGap = _maxFps > 0 ? 1000 / _maxFps : 0;
+var _lastDraw = 0;
 sceneRender();
 window.addEventListener('resize', sceneRender);
 (function sceneLoop() {
-    sceneRender();
     window._sceneRaf = requestAnimationFrame(sceneLoop);
+    var t = performance.now();
+    if (_frameGap && t - _lastDraw < _frameGap - 1) return;
+    _lastDraw = t;
+    sceneRender();
 })();
 
         function hexToRgb(h) {

config.js

@@ -87,6 +87,9 @@ window.CONFIG = {
     // render the clouds/map shader at reduced resolution and upscale
     // via CSS - use it if fps is low (GPU-bound) despite a quiet CPU.
     renderScale: 1,
+    // WebGL scene frame cap (default 30; 0 = free-running/vsync). All
+    // scene motion is time-based, so the cap only changes smoothness.
+    maxFps: 30,
     location: {
         // Latitude and longitude for sun/moon calculations
         // Passau (vorher: Muenchen 48.1374/11.5755, Innsbruck 47.2692/11.4041)