Particle[] particles = this.particles;
boolean[] active = this.active;
BoundingBox bounds = this.bounds;
bounds.inf();
for (int i = 0, n = active.length; i < n; i++)
if (active[i]) {
Rectangle r = particles[i].getBoundingRectangle();
bounds.ext(r.x, r.y, 0);
bounds.ext(r.x + r.width, r.y + r.height, 0);