Method setupEscape

src/Battlescape/AlienBAIState.cpp:757–950

* Attempts to find cover, and move toward it. * The idea is to check within a 11x11 tile square for a tile which is not seen by our aggroTarget. * If there is no such tile, we run away from the target. * Fills out the _escapeAction with useful data. */

 * Fills out the _escapeAction with useful data.
 */
void AlienBAIState::setupEscape()
{
	int unitsSpottingMe = getSpottingUnits(_unit->getPosition());
	int currentTilePreference = 15;
	int tries = -1;
	bool coverFound = false;
	selectNearestTarget();
	_escapeTUs = 0;

	int dist = _aggroTarget ? _save->getTileEngine()->distance(_unit->getPosition(), _aggroTarget->getPosition()) : 0;

	int bestTileScore = -100000;
	int score = -100000;
	Position bestTile(0, 0, 0);

	Tile *tile = 0;

	// weights of various factors in choosing a tile to which to withdraw
	const int EXPOSURE_PENALTY = 10;
	const int FIRE_PENALTY = 40;
	const int BASE_SYSTEMATIC_SUCCESS = 100;
	const int BASE_DESPERATE_SUCCESS = 110;
	const int FAST_PASS_THRESHOLD = 100; // a score that's good engouh to quit the while loop early; it's subjective, hand-tuned and may need tweaking

	std::vector<Position> randomTileSearch = _save->getTileSearch();
	RNG::shuffle(randomTileSearch);
	
	while (tries < 150 && !coverFound)
	{
		_escapeAction->target = _unit->getPosition(); // start looking in a direction away from the enemy
					
		if (!_save->getTile(_escapeAction->target))
		{
			_escapeAction->target = _unit->getPosition(); // cornered at the edge of the map perhaps? 
		}
		
		score = 0;

		if (tries == -1)
		{
			// you know, maybe we should just stay where we are and not risk reaction fire... 
			// or maybe continue to wherever we were running to and not risk looking stupid
			if (_save->getTile(_unit->lastCover) != 0)
			{
				_escapeAction->target = _unit->lastCover;
			} 
		}
		else if (tries < 121) 
		{
			// looking for cover
			_escapeAction->target.x += randomTileSearch[tries].x;
			_escapeAction->target.y += randomTileSearch[tries].y;
			score = BASE_SYSTEMATIC_SUCCESS;
			if (_escapeAction->target == _unit->getPosition()) 
			{
				if (unitsSpottingMe > 0)
				{
					// maybe don't stay in the same spot? move or something if there's any point to it?