From 5fedaa299ba01ac032f4b4ff4215cbde41f5f58b Mon Sep 17 00:00:00 2001
From: CN-JS-HuiBai <huyang@littlediary.cn>
Date: Mon, 6 Apr 2026 01:23:00 +0800
Subject: [PATCH] =?UTF-8?q?=E4=BC=98=E5=8C=96=E7=BA=BF=E8=B7=AF=E5=9B=BE?=
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---
 public/js/app.js | 37 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/public/js/app.js b/public/js/app.js
index f8ba033..53374e7 100644
--- a/public/js/app.js
+++ b/public/js/app.js
@@ -782,6 +782,41 @@
             const endCoords = getShiftedCoords(route.dest);
 
             if (startCoords && endCoords) {
+                // Calculate direction and distance
+                const dx = endCoords[0] - startCoords[0];
+                const dy = endCoords[1] - startCoords[1];
+                
+                // Identify major regions
+                const src = (route.source || '').toLowerCase();
+                const dst = (route.dest || '').toLowerCase();
+                
+                const isUS = (n) => n.includes('united states') || n.includes('us ') || n.includes('seattle') || n.includes('san francisco') || n.includes('los angeles') || n.includes('new york') || n.includes('chicago');
+                const isJapan = (n) => n.includes('japan') || n.includes('tokyo');
+                const isAsia = (n) => n.includes('china') || n.includes('hong kong') || n.includes('singapore') || n.includes('korea') || n.includes('seoul') || n.includes('japan') || n.includes('tokyo') || n.includes('shanghai') || n.includes('beijing');
+                const isEurope = (n) => n.includes('germany') || n.includes('uk') || n.includes('france') || n.includes('london') || n.includes('frankfurt') || n.includes('paris') || n.includes('united kingdom');
+
+                // Determine base curveness to always bend North (Upward) for major East-West routes
+                // In this map: dx < 0 (Westward) -> negative curveness bends North
+                //              dx > 0 (Eastward) -> positive curveness bends North
+                let baseCurve = 0.2;
+                if (dx < 0) baseCurve = -0.2;
+
+                // Special case: Trans-Pacific (US <-> Japan/Asia) - usually deeper curve
+                if ((isUS(src) && isAsia(dst)) || (isAsia(src) && isUS(dst))) {
+                    baseCurve = (dx < 0 ? -0.35 : 0.35);
+                } 
+                // Trans-Atlantic (US <-> Europe) - use coordinates to detect
+                else if ((isUS(src) && isEurope(dst)) || (isEurope(src) && isUS(dst))) {
+                    baseCurve = (dx < 0 ? -0.25 : 0.25);
+                }
+                // Intra-Asia or shorter routes - flatter curve
+                else if (Math.abs(dx) < 50) {
+                    baseCurve = (dx < 0 ? -0.15 : 0.15);
+                }
+
+                // Add variation for multiple lines to same destination
+                const finalCurve = baseCurve + (index * 0.04 * (baseCurve > 0 ? 1 : -1));
+
                 finalSeries.push({
                     type: 'lines',
                     coordinateSystem: 'geo',
@@ -798,7 +833,7 @@
                     lineStyle: {
                         color: 'rgba(99, 102, 241, 0.3)',
                         width: 2,
-                        curveness: 0.2 + (index * 0.1) // Slightly different curves for clarity
+                        curveness: finalCurve
                     },
                     tooltip: {
                         formatter: () => {