Method setWaveCountdown

src/Savegame/AlienMission.cpp:554–562

* The new time must be a multiple of 30 minutes, and more than 0. * Calling this on a finished mission has no effect. * @param minutes The minutes until the next UFO wave will spawn. */

 * @param minutes The minutes until the next UFO wave will spawn.
 */
void AlienMission::setWaveCountdown(size_t minutes)
{
	assert(minutes != 0 && minutes % 30 == 0);
	if (isOver())
	{
		return;
	}
	_spawnCountdown = minutes;
}

/**
 * Assigns a unique ID to this mission.