private PointQuadtree tree;
public void draw() {
background(255);
Circle c = new Circle(new Vec2D(mouseX, mouseY), 100);
Rect r = new Rect(200, 200, 300, 100);
stroke(r.intersectsCircle(c, c.getRadius()) ? 0xffff0000 : 0xff000000);
noFill();
gfx.ellipse(c);
gfx.rect(r);
List<Vec2D> sel = tree.itemsWithinRadius(c, c.getRadius(), null);
// List<Vec2D> sel = tree.itemsWithinRect(new Rect(mouseX, mouseY, 200,
// 100), null);
noStroke();
fill(0);
if (sel != null) {