Ch 10. Buggy tick() by server when spawning enemies

[kyuhyunp]

Here is how the GameServer spawns enemies randomly.

        // Check if its time to attempt to spawn enemies
	if (now() >= mTimeForNextSpawn + mLastSpawnTime)
	{	
		// No more enemies are spawned near the end
		if (mBattleFieldRect.top > 600.f)
		{
			std::size_t enemyCount = 1u + randomInt(2);
			float spawnCenter = static_cast<float>(randomInt(500) - 250);

			// In case only one enemy is being spawned, it appears directly at the spawnCenter
			float planeDistance = 0.f;
			float nextSpawnPosition = spawnCenter;
			
			// In case there are two enemies being spawned together, each is spawned at each side of the spawnCenter, with a minimum distance
			if (enemyCount == 2)
			{
				planeDistance = static_cast<float>(150 + randomInt(250));
				nextSpawnPosition = spawnCenter - planeDistance / 2.f;
			}

			// Send the spawn orders to all clients
			for (std::size_t i = 0; i < enemyCount; ++i)
			{
				sf::Packet packet;
				packet << static_cast<sf::Int32>(Server::SpawnEnemy);
				packet << static_cast<sf::Int32>(1 + randomInt(Aircraft::TypeCount-1));
				packet << mWorldHeight - mBattleFieldRect.top + 500;
				packet << nextSpawnPosition;

				nextSpawnPosition += planeDistance / 2.f;

				sendToAll(packet);
			}

			mLastSpawnTime = now();
			mTimeForNextSpawn = sf::milliseconds(2000 + randomInt(6000));
		}
	

There a problem with planeDistance where nextSpawnPosition in the loop should be nextSpawnPosition += planeDistance; Otherwise, the plane Distance is halved.

Also, packet << mWorldHeight - mBattleFieldRect.top + 500; seems confusing but means 500.f above the mBattleFieldRect.top after addEnemy because mSpawnPositon.y is equal to mWorldHeight.

void World::addEnemy(Aircraft::Type type, float relX, float relY)
{
	SpawnPoint spawn(type, mSpawnPosition.x + relX, mSpawnPosition.y - relY);
	mEnemySpawnPoints.push_back(spawn);
}

void World::setCurrentBattleFieldPosition(float lineY)
{
	mWorldView.setCenter(mWorldView.getCenter().x, lineY - mWorldView.getSize().y/2);
	mSpawnPosition.y = mWorldBounds.height; 
}

It would be much safer if there was another method for addEnemy for multiplayer instead of destroying the meaning of mSpawnPosition.