From 7f733b8efe68424abc6e9d5af296ff12325e6285 Mon Sep 17 00:00:00 2001
From: Richard Zink <Richard Zink>
Date: Mon, 12 Oct 2026 17:33:31 +0200
Subject: [PATCH] atmosphere: smooth front haze with 24-bit distance and dither

---
 vendor/clouds3d.js | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/vendor/clouds3d.js b/vendor/clouds3d.js
index fc961a3..f352136 100644
--- a/vendor/clouds3d.js
+++ b/vendor/clouds3d.js
@@ -460,15 +460,18 @@ var FRAG_SRC = [
         'if (uMode == 3) {',
             'if (uFrontHazeOn < 0.5) { gl_FragColor = vec4(0.0); return; }',
             'vec2 uv = gl_FragCoord.xy / uResolution;',
-            'float distNorm = texture2D(uTerrainDistTex, uv).a;',
+            'vec4 distTex = texture2D(uTerrainDistTex, uv);',
             'float column = 0.0;',
-            'if (distNorm > 0.0005 && distNorm < 0.999) {',
+            'if (distTex.a > 0.5) {',
+                'float distNorm = (distTex.r * 65536.0 + distTex.g * 256.0 + distTex.b) / 16777215.0;',
                 'column = hazeColumnToDistance(rd, distNorm * max(1.0, uFarPlane));',
             '} else {',
                 'column = airHazeColumn(rd);',
             '}',
             'float tau = uFrontHazeDensity * column;',
             'float alpha = clamp((1.0 - exp(-tau)) * uFrontHazeGain, 0.0, uFrontHazeMaxAlpha);',
+            'float dither = fract(sin(dot(gl_FragCoord.xy, vec2(12.9898, 78.233))) * 43758.5453);',
+            'alpha = clamp(alpha + (dither - 0.5) / 255.0, 0.0, uFrontHazeMaxAlpha);',
             'gl_FragColor = vec4(uFrontHazeColor, alpha);',
             'return;',
         '}',
@@ -818,7 +821,11 @@ var TERRAIN_FRAG_SRC = [
     'void main() {',
         'if (uDistancePassOn > 0.5) {',
             'float d = clamp(length(vViewPos) / max(1.0, uFarPlane), 0.0, 1.0);',
-            'gl_FragColor = vec4(0.0, 0.0, 0.0, d);',
+            'float v = d * 16777215.0;',
+            'float r = floor(v / 65536.0) / 255.0;',
+            'float g = floor(mod(v, 65536.0) / 256.0) / 255.0;',
+            'float b = floor(mod(v, 256.0)) / 255.0;',
+            'gl_FragColor = vec4(r, g, b, 1.0);',
             'return;',
         '}',
         'vec2 gUv = vUV;',
@@ -2274,8 +2281,8 @@ function ensureTerrainDistFbo(gl, w, h) {
     terrainDistTex = gl.createTexture();
     gl.bindTexture(gl.TEXTURE_2D, terrainDistTex);
     gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, w, h, 0, gl.RGBA, gl.UNSIGNED_BYTE, null);
-    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
-    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
+    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
+    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
     gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
     gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
     terrainDistDepth = gl.createRenderbuffer();