var upgradeInterval = 500;
var currentUpgrade = false;

function updateUpgrade() {
	if (currentUpgrade) {
		currentUpgrade.move();
		if (currentUpgrade.isIndsideObj(playerShip.obj)) {
			playerShip.weapon++;
			currentUpgrade=false;
		} else if (!currentUpgrade.isIndsideObj(canvas)) {
			currentUpgrade=false;
		}
	} else if (gameCounter % upgradeInterval == 0) {
		currentUpgrade = new FlyingObj();
		currentUpgrade.img.src = "data/graphics/shotupgrade.png";
		currentUpgrade.posRandomNewItem();
		currentUpgrade.dirX = -2;
		currentUpgrade.init();
	}
}