优化线条

public/js/app.js

@@ -976,18 +976,26 @@
           const pts = [start, end].slice().sort((a, b) => a[0] - b[0] || a[1] - b[1]);
           const isForward = (start === pts[0]);
 
-          // Simplified calculation to reduce crossings
+          // Normalization and special routing rules
-          // Maintaining a consistent direction for single lines ensures that parallel paths stay parallel
+          const lowS = (route.source || '').toLowerCase().trim();
+          const lowD = (route.dest || '').toLowerCase().trim();
+          const isSeattleJapan = ( (lowS === 'seattle' || lowS === 'us seattle') && lowD === 'japan' ) ||
+                                 ( (lowD === 'seattle' || lowD === 'us seattle') && lowS === 'japan' );
+
           let finalCurve = 0;
-          if (count === 1) {
+          if (isSeattleJapan) {
-            // Subtle consistent curve for single routes
+            // Special rule: Seattle ↔ Japan route curves upward (North)
+            // For Seattle -> Japan (Westbound): Right is North (+).
+            // For Japan -> Seattle (Eastbound): Right is South (+), so North is (-).
+            const isWestbound = (lowS === 'seattle' || lowS === 'us seattle');
+            finalCurve = isWestbound ? 0.3 : -0.3;
+          } else if (count === 1) {
+            // Subtle consistent curve for single routes to maintain parallelism
             finalCurve = 0.12;
           } else {
             // Symmetrical fan-out for multiple lines between the same points
-            // This spreads them cleanly into "eye" shapes without biased clustering
             const magnitude = 0.12 + Math.floor(i / 2) * 0.12;
             const spread = (i % 2 === 0) ? magnitude : -magnitude;
-            // Ensure visual consistency regardless of the data direction (A->B or B->A)
             finalCurve = isForward ? spread : -spread;
           }