atmosphere: make haze night-cycle aware

vendor/clouds3d.js

@@ -2777,6 +2777,16 @@ function airlightColor(altRad, moonAlt, moonFrac) {
 // (0 = pure physics, 1 = the theme colour), and gain / nightGain scale the
 // day and night exposure. Configured per theme in window.THEMES[theme].
 // .lighting; a theme without that block is pure physics.
+function hazeColorDynamic(base, air, amb, star, moonI) {
+    var target = 0.07 + 1.15 * Math.max(0, amb) + 0.55 * Math.max(0, star)
+        + 0.25 * Math.max(0, moonI);
+    target = Math.max(0.06, Math.min(0.72, target));
+    var col = mixRgb(base, air, 0.55);
+    var lum = 0.2126 * col[0] + 0.7152 * col[1] + 0.0722 * col[2];
+    var scale = target / Math.max(0.02, lum);
+    scale = Math.max(0.05, Math.min(2.5, scale));
+    return [col[0] * scale, col[1] * scale, col[2] * scale];
+}
 function themeColor(v, fallback) {
     if (typeof v === 'number') return hex(v);
     if (typeof v === 'string') {
@@ -5812,6 +5822,12 @@ window.clouds3dRender = function(target) {
         _moonI *= _exp;
         _amb *= _exp;
     }
+    var _terrainHazeColor = hazeColorDynamic(TERRAIN_HAZE_COLOR, _air, _amb, _star, _moonI);
+    var _frontHazeColor = hazeColorDynamic(FRONT_HAZE_COLOR, _air, _amb, _star, _moonI);
+    var _airHazeColor = hazeColorDynamic(AIR_HAZE_COLOR, _air, _amb, _star, _moonI);
+    var _hazeMaxScale = 0.35 + 1.1 * Math.max(0, _amb) + 0.45 * Math.max(0, _star)
+        + 0.25 * Math.max(0, _moonI);
+    _hazeMaxScale = Math.max(0.25, Math.min(1.0, _hazeMaxScale));
     gl.uniform3f(s.uAirColor, _air[0], _air[1], _air[2]);
     gl.uniform3f(s.uRayleighBeta, TAU_RAYLEIGH[0], TAU_RAYLEIGH[1], TAU_RAYLEIGH[2]);
     gl.uniform1f(s.uSunAirMass, airMass(Math.max(sunAlt, 0.0)));
@@ -5822,14 +5838,14 @@ window.clouds3dRender = function(target) {
     gl.uniform1f(s.uAirHazeScaleHeightUnits, AIR_HAZE_SCALE_HEIGHT_UNITS);
     gl.uniform1f(s.uAirHazeGain, AIR_HAZE_GAIN);
     gl.uniform1f(s.uAirHazeMaxAlpha, AIR_HAZE_MAX_ALPHA);
-    gl.uniform3f(s.uAirHazeColor, AIR_HAZE_COLOR[0], AIR_HAZE_COLOR[1], AIR_HAZE_COLOR[2]);
+    gl.uniform3f(s.uAirHazeColor, _airHazeColor[0], _airHazeColor[1], _airHazeColor[2]);
     gl.uniform1i(s.uTerrainDistTex, 7);
     gl.uniform1f(s.uFrontHazeOn, FRONT_HAZE_ON ? 1.0 : 0.0);
     gl.uniform1f(s.uFrontHazeDensity, FRONT_HAZE_DENSITY);
     gl.uniform1f(s.uFrontHazeScaleHeightUnits, FRONT_HAZE_SCALE_HEIGHT_UNITS);
     gl.uniform1f(s.uFrontHazeGain, FRONT_HAZE_GAIN);
-    gl.uniform1f(s.uFrontHazeMaxAlpha, FRONT_HAZE_MAX_ALPHA);
+    gl.uniform1f(s.uFrontHazeMaxAlpha, FRONT_HAZE_MAX_ALPHA * _hazeMaxScale);
-    gl.uniform3f(s.uFrontHazeColor, FRONT_HAZE_COLOR[0], FRONT_HAZE_COLOR[1], FRONT_HAZE_COLOR[2]);
+    gl.uniform3f(s.uFrontHazeColor, _frontHazeColor[0], _frontHazeColor[1], _frontHazeColor[2]);
     gl.uniform1f(s.uFarPlane, 100.0);
     gl.uniform3f(s.uSunColor, _beam[0], _beam[1], _beam[2]);
     gl.uniform1f(s.uSunInt, _beamL);
@@ -6125,8 +6141,8 @@ window.clouds3dRender = function(target) {
         gl.uniform1f(terr.uHazeDensity, TERRAIN_HAZE_DENSITY);
         gl.uniform1f(terr.uHazeScaleHeightUnits, TERRAIN_HAZE_SCALE_HEIGHT_UNITS);
         gl.uniform1f(terr.uHazeGain, TERRAIN_HAZE_GAIN);
-        gl.uniform1f(terr.uHazeMaxAlpha, TERRAIN_HAZE_MAX_ALPHA);
+        gl.uniform1f(terr.uHazeMaxAlpha, TERRAIN_HAZE_MAX_ALPHA * _hazeMaxScale);
-        gl.uniform3f(terr.uHazeColor, TERRAIN_HAZE_COLOR[0], TERRAIN_HAZE_COLOR[1], TERRAIN_HAZE_COLOR[2]);
+        gl.uniform3f(terr.uHazeColor, _terrainHazeColor[0], _terrainHazeColor[1], _terrainHazeColor[2]);
 
         gl.bindBuffer(gl.ARRAY_BUFFER, terr.vbo);
         var STRIDE = 11 * 4; // 11 floats per vertex