public boolean collision(Agent b, boolean thump) {
        boolean result = false;

        if (b.wallCollision()) {
            result = true;
            if (thump)
                b.thump();
        }
        for (int i = 0; i < agents.length; i++) {
            if (agents[i] != null && agents[i].id != b.id &&
                agents[i].thingCollision(b)) {
                result = true;
                if (thump) {
                    b.thump();
                    agents[i].thump();
                }
            }
        }
        return result;
    }