hitTestInput method

@override DisplayObject? hitTestInput(num localX, num localY)

Evaluates this display object to see if the coordinates localX and localY are inside this display object.

If the coordinates are inside, this display object is returned; null otherwise.

localX and localY are relative to to the origin (0,0) of this display object (local coordinates).

Implementation

@override
DisplayObject? hitTestInput(num localX, num localY) {
  for (var i = 0; i < ixList.length - 2; i += 3) {
    final i1 = ixList[i + 0] << 2;
    final i2 = ixList[i + 1] << 2;
    final i3 = ixList[i + 2] << 2;

    final x1 = vxList[i1 + 0];
    final y1 = vxList[i1 + 1];
    final x2 = vxList[i2 + 0];
    final y2 = vxList[i2 + 1];
    final x3 = vxList[i3 + 0];
    final y3 = vxList[i3 + 1];

    if (localX < x1 && localX < x2 && localX < x3) continue;
    if (localX > x1 && localX > x2 && localX > x3) continue;
    if (localY < y1 && localY < y2 && localY < y3) continue;
    if (localY > y1 && localY > y2 && localY > y3) continue;

    final vx1 = x3 - x1;
    final vy1 = y3 - y1;
    final vx2 = x2 - x1;
    final vy2 = y2 - y1;
    final vx3 = localX - x1;
    final vy3 = localY - y1;

    final dot11 = vx1 * vx1 + vy1 * vy1;
    final dot12 = vx1 * vx2 + vy1 * vy2;
    final dot13 = vx1 * vx3 + vy1 * vy3;
    final dot22 = vx2 * vx2 + vy2 * vy2;
    final dot23 = vx2 * vx3 + vy2 * vy3;

    final u =
        (dot22 * dot13 - dot12 * dot23) / (dot11 * dot22 - dot12 * dot12);
    final v =
        (dot11 * dot23 - dot12 * dot13) / (dot11 * dot22 - dot12 * dot12);

    if ((u >= 0) && (v >= 0) && (u + v < 1)) return this;
  }

  return null;
}