private function cannonRect()
{
$result = new QRect(0, 0, 50, 50);
$result->moveBottomLeft($this->rect()->bottomLeft());
return $result;
}
private function shotRect()
{
$gravity = 4.0;
$time = $this->timerCount / 20.0;
$velocity = $this->shootForce;
$radians = $this->shootAngle * 3.14159265 / 180;
$velx = $velocity * cos($radians);
$vely = $velocity * sin($radians);
$x0 = ($this->barrelRect->right() + 5) * cos($radians);
$y0 = ($this->barrelRect->right() + 5) * sin($radians);
$x = $x0 + $velx * $time;
$y = $y0 + $vely * $time - 0.5 * $gravity * $time * $time;
$result = new QRect(0, 0, 6, 6);
$result->moveCenter(new QPoint(qRound($x), $this->height() - 1 - qRound($y)));
return $result;
}