From d6de63d3445ab10072609db2e695d67560c68692 Mon Sep 17 00:00:00 2001
From: Andrea Manzi <manzolo@libero.it>
Date: Sun, 25 Oct 2026 00:33:14 +0200
Subject: [PATCH] =?UTF-8?q?Le=20nuvole=20che=20scorrono=20non=20spariscono?=
 =?UTF-8?q?=20pi=C3=B9=20passando=20sopra=20quelle=20dipinte=20nello=20sfo?=
 =?UTF-8?q?ndo?=
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Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ApqNBvNbNCwXqR2RLo8QJh
---
 src/engine/render.js | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/src/engine/render.js b/src/engine/render.js
index 0636e24..18c5fa1 100644
--- a/src/engine/render.js
+++ b/src/engine/render.js
@@ -210,11 +210,20 @@ function skyMask(bg) {
         c.width = WIDTH; c.height = HEIGHT;
         const x = c.getContext('2d');
         x.drawImage(bg, 0, 0, WIDTH, HEIGHT);
-        const img = x.getImageData(0, 0, WIDTH, HEIGHT), d = img.data;
-        for (let p = 0; p < d.length; p += 4) {
-            const sky = d[p + 2] > 150 && d[p + 2] - d[p] > 60 && d[p + 2] - d[p + 1] > 15;
-            d[p + 3] = sky ? 255 : 0;
+        const img = x.getImageData(0, 0, WIDTH, HEIGHT), d = img.data, W = WIDTH, H = HEIGHT;
+        const sky = new Uint8Array(W * H);
+        for (let i = 0; i < W * H; i++) sky[i] = d[i * 4 + 2] > 150 && d[i * 4 + 2] - d[i * 4] > 60 && d[i * 4 + 2] - d[i * 4 + 1] > 15 ? 1 : 0;
+        // Le nuvole dipinte nello sfondo sono cielo anche loro (sennò le nuvole nuove ci spariscono dietro): pixel chiari
+        // con del cielo azzurro vicino a sinistra, a destra, sopra e sotto. Un muro chiaro sotto non ha cielo: resta fuori.
+        const near = (i, step, n) => { for (let k = 1, j = i; k <= n; k++) { j += step; if (j < 0 || j >= W * H) return false; if (sky[j]) return true; } return false; };
+        const out = sky.slice();
+        for (let i = 0; i < W * H; i++) {
+            if (sky[i]) continue;
+            const r = d[i * 4], g = d[i * 4 + 1], bl = d[i * 4 + 2], col = i % W;
+            if (r + g + bl < 540 || bl < 140) continue;
+            if (near(i, -1, Math.min(40, col)) && near(i, 1, Math.min(40, W - 1 - col)) && near(i, -W, 24) && near(i, W, 24)) out[i] = 1;
         }
+        for (let i = 0; i < W * H; i++) d[i * 4 + 3] = out[i] ? 255 : 0;
         x.putImageData(img, 0, 0);
         mask = c;
     } catch { /* senza canvas (test) niente nuvole */ }