task(B3): offset respects click side (fixes BUG-3)

2026-08-26 13:51:02 +02:00
parent 95b14cf86b
commit d8f29e42e3
3 changed files with 61 additions and 7 deletions
@@ -761,7 +761,23 @@ export class InteractionEngine {
      if (this.modifySelected.length === 1) {
        const first = this.state.points[0];
        const dist = distance(first, pt);
-        const offsetted = offsetElement(this.modifySelected[0], dist);
+        const base = this.modifySelected[0];
+        // Seitigkeit bestimmen: Kreuzprodukt der Linienrichtung mit Klickvektor.
+        // cross > 0 → Klick links der Laufrichtung (p1→p2) → side=+1, sonst -1.
+        let side: 1 | -1 = 1;
+        if (base.type === 'line' && base.properties.x1 !== undefined && base.properties.y1 !== undefined) {
+          const p1x = base.properties.x1 as number;
+          const p1y = base.properties.y1 as number;
+          const p2x = base.properties.x2 as number;
+          const p2y = base.properties.y2 as number;
+          const cross = (p2x - p1x) * (pt.y - p1y) - (p2y - p1y) * (pt.x - p1x);
+          side = cross >= 0 ? 1 : -1;
+        } else if ((base.type === 'circle' || base.type === 'arc') && base.properties.radius !== undefined) {
+          // Kreis/Bogen: Klick außerhalb → vergrößern (+1), innerhalb → verkleinern (-1)
+          const clickDist = Math.hypot(pt.x - base.x, pt.y - base.y);
+          side = clickDist >= base.properties.radius ? 1 : -1;
+        }
+        const offsetted = offsetElement(base, dist, side);
        // Create as new element (copy)
        this.onElementCreated?.({ ...offsetted, id: this.generateId() });
        this.resetModify();