clouds: clip only against curved horizon, not detailed terrain

vendor/clouds3d.js

@@ -446,16 +446,9 @@ var FRAG_SRC = [
         'float tTerrain = -1.0;',
         'if (terrRoots.x > 0.0) tTerrain = terrRoots.x;',
         'else if (terrRoots.y > 0.0) tTerrain = terrRoots.y;',
-        'if (tTerrain > 0.0 && uElevOn > 0.5 && rd.y < -0.01) {',
+        // Keep cloud occlusion on the curved Earth horizon only. Detailed
-            'for (int ti = 0; ti < 4; ti++) {',
+        // terrain-height clipping made the deck boil and cut holes.
-                'vec3 hp = ro + rd * tTerrain;',
+        'if (tTerrain < 0.1) tTerrain = -1.0;',
-                'float terrainY = terrElev(hp.xz) * uElevScale - earthDrop(hp.xz);',
-                'float dh = terrainY - hp.y;',
-                'if (abs(dh) < 0.02) break;',
-                'tTerrain -= dh / -rd.y;',
-                'if (tTerrain < 0.1 || tTerrain > 90.0) { tTerrain = -1.0; break; }',
-            '}',
-        '}',
         // Cloud march. The output is the cloud's effective colour and
         // coverage (alpha); the render pass uses alpha-blend so the
         // terrain mesh from the previous pass shows through transparent