Method findEdgeAt

ui/src/components/pixi/PixiRenderer.ts:2165–2222

* Find the nearest edge to (worldX, worldY) within maxDistance. * Uses point-to-segment (or point-to-quadratic-curve) distance testing.

(worldX: number, worldY: number, maxDistance = 8)

   * Uses point-to-segment (or point-to-quadratic-curve) distance testing.
   */
  findEdgeAt(worldX: number, worldY: number, maxDistance = 8): PixiEdge | null {
    if (this.edges.length === 0) return null;

    let bestEdge: PixiEdge | null = null;
    let bestDist = maxDistance;

    for (let i = 0; i < this.edges.length; i++) {
      const e = this.edges[i];
      if (this.hiddenLinkTypes.has(e.label)) continue;
      const s = this.nodes.get(e.sourceId);
      const t = this.nodes.get(e.targetId);
      if (!s?.visible || !t?.visible) continue;

      const sx = this.mode3d ? s.sprite.position.x : s.x;
      const sy = this.mode3d ? s.sprite.position.y : s.y;
      const tx = this.mode3d ? t.sprite.position.x : t.x;
      const ty = this.mode3d ? t.sprite.position.y : t.y;

      // Early bounding-box pruning
      const dx = tx - sx;
      const dy = ty - sy;
      const lenSq = dx * dx + dy * dy;
      const isCurve = this.bp.edgeStyle === 'curve';
      const padding =
        maxDistance + (isCurve ? Math.sqrt(lenSq) * this.curvature : 0);

      if (
        worldX < Math.min(sx, tx) - padding ||
        worldX > Math.max(sx, tx) + padding ||
        worldY < Math.min(sy, ty) - padding ||
        worldY > Math.max(sy, ty) + padding
      ) {
        continue;
      }

      let dist: number;
      if (isCurve) {
        dist = pointToQuadraticDist(
          worldX,
          worldY,
          sx,
          sy,
          tx,
          ty,
          this.curvature,
        );
      } else {
        dist = pointToSegmentDist(worldX, worldY, sx, sy, tx, ty);
      }

      if (dist < bestDist) {
        bestDist = dist;
        bestEdge = e;
      }
    }

    return bestEdge;
  }