config: allow clouds in front of terrain

config.js

@@ -339,6 +339,11 @@ window.CONFIG = {
         // ready. This avoids clouds appearing over an unfinished ground model.
         waitForTerrain: true,     // false = draw clouds immediately
         // waitForTerrain: false
+        // Terrain occlusion for clouds. false draws clouds in front of the
+        // terrain mesh even when terrain is closer; true clips cloud rays
+        // against the terrain distance buffer.
+        terrainOcclusion: false,  // inverted occlusion: clouds stay in front
+        // terrainOcclusion: true
         // Coverage per weather level, 0 = clear, 1 = overcast. Only the
         // levels listed here override the built-in defaults
         // (sunny 0.20, cloudy 0.70, stormy 0.80, night 0.45). Live weather

vendor/clouds3d.js

@@ -1506,6 +1506,7 @@ var CLOUD_NEAR_FADE_START = (typeof CLOUD_NEAR_FADE_CFG.start === 'number') ? Ma
 var CLOUD_NEAR_FADE_END = Math.max(CLOUD_NEAR_FADE_START + 0.1, (typeof CLOUD_NEAR_FADE_CFG.end === 'number') ? CLOUD_NEAR_FADE_CFG.end : 2.5);
 var CLOUDS_ON = !(window.CONFIG && window.CONFIG.clouds && window.CONFIG.clouds.enabled === false);
 var CLOUDS_WAIT_FOR_TERRAIN = !(window.CONFIG && window.CONFIG.clouds && window.CONFIG.clouds.waitForTerrain === false);
+var CLOUD_TERRAIN_OCCLUSION = !(window.CONFIG && window.CONFIG.clouds && window.CONFIG.clouds.terrainOcclusion === false);
 function cloudsActive() {
     return CLOUDS_ON && (!CLOUDS_WAIT_FOR_TERRAIN || (elevTexture && terrainVbo));
 }
@@ -8030,7 +8031,7 @@ window.clouds3dRender = function(target) {
         gl.activeTexture(gl.TEXTURE7);
         gl.bindTexture(gl.TEXTURE_2D, terrainDistTex || null);
         gl.uniform1i(s.uTerrainDistTex, 7);
-        gl.uniform1f(s.uTerrainDistOk, (terrainDistOk && terrainDistTex) ? 1.0 : 0.0);
+        gl.uniform1f(s.uTerrainDistOk, (terrainDistOk && terrainDistTex && CLOUD_TERRAIN_OCCLUSION) ? 1.0 : 0.0);
         gl.disable(gl.DEPTH_TEST);
         gl.depthMask(false);
         gl.enable(gl.BLEND);