/**
* Calculate the shortest path using a simple A-Star algorithm.
* The unit information and movement type must have already been set.
* The path information is set only if a valid path is found.
* @param startPosition The position to start from.
* @param endPosition The position we want to reach.
* @return True if a path exists, false otherwise.
*/
bool Pathfinding::aStarPath(const Position &startPosition, const Position &endPosition)
{
// reset every node, so we have to check them all
for (std::vector<PathfindingNode>::iterator it = _nodes.begin(); it != _nodes.end(); ++it)
it->reset();
// start position is the first one in our "open" list
PathfindingNode *start = getNode(startPosition);
start->connect(0, 0, 0, endPosition);
PathfindingOpenSet openList;
openList.push(start);
// if the open list is empty, we've reached the end
while(!openList.empty())
{
PathfindingNode *currentNode = openList.pop();
Position const ¤tPos = currentNode->getPosition();
currentNode->setChecked();
if (currentPos == endPosition) // We found our target.
{
_path.clear();
PathfindingNode *pf = currentNode;
while (pf->getPrevNode())
{
_path.push_back(pf->getPrevDir());
pf = pf->getPrevNode();
}
return true;
}
// Try all reachable neighbours.
for (int direction = 0; direction < 10; direction++)
{
Position nextPos;
int tuCost = getTUCost(currentPos, direction, &nextPos, _unit);
if (tuCost == 255) // Skip unreachable / blocked
continue;
PathfindingNode *nextNode = getNode(nextPos);
if (nextNode->isChecked()) // Our algorithm means this node is already at minimum cost.
continue;
int totalTuCost = currentNode->getTUCost() + tuCost;
// If this node is unvisited or visited from a better path.
if (!nextNode->inOpenSet() || nextNode->getTUCost() > totalTuCost)
{
nextNode->connect(totalTuCost, currentNode, direction, endPosition);
openList.push(nextNode);
}
}
}
// Unble to reach the target
return false;
}
void Pathfinding::calculate(BattleUnit *unit, Position &endPosition)
{
std::list<PathfindingNode*> openList;
Position currentPos, nextPos, startPosition = unit->getPosition();
int tuCost;
_movementType = MT_WALK; // should be parameter
_unit = unit;
Tile *destinationTile = _save->getTile(endPosition);
// check if destination is not blocked
if (isBlocked(destinationTile, MapData::O_FLOOR) || isBlocked(destinationTile, MapData::O_OBJECT)) return;
// the following check avoids that the unit walks behind the stairs if we click behind the stairs to make it go up the stairs.
// it only works if the unit is on one of the 2 tiles on the stairs, or on the tile right in front of the stairs.
if (isOnStairs(startPosition, endPosition))
{
endPosition.z++;
destinationTile = _save->getTile(endPosition);
}
// check if we have floor, else lower destination (for non flying units only, because otherwise they never reached this place)
while (canFallDown(destinationTile))
{
endPosition.z--;
destinationTile = _save->getTile(endPosition);
}
_path.clear();
// reset every node, so we have to check them all
for (int i = 0; i < _size; ++i)
_nodes[i]->reset();
// start position is the first one in our "open" list
openList.push_back(getNode(startPosition));
openList.front()->check(0, 0, 0, 0);
// if the open list is empty, we've reached the end
while(!openList.empty())
{
// this algorithm expands in all directions
for (int direction = 0; direction < 8; direction++)
{
currentPos = openList.front()->getPosition();
tuCost = getTUCost(currentPos, direction, &nextPos, unit);
if(tuCost < 255)
{
if( (!getNode(nextPos)->isChecked() ||
getNode(nextPos)->getTUCost() > getNode(currentPos)->getTUCost() + tuCost) &&
(!getNode(endPosition)->isChecked() ||
getNode(endPosition)->getTUCost() > getNode(currentPos)->getTUCost() + tuCost)
)
{
getNode(nextPos)->check(getNode(currentPos)->getTUCost() + tuCost,
getNode(currentPos)->getStepsNum() + 1,
getNode(currentPos),
direction);
openList.push_back(getNode(nextPos));
}
}
}
openList.pop_front();
}
if(!getNode(endPosition)->isChecked()) return;
//Backward tracking of the path
PathfindingNode* pf = getNode(endPosition);
for (int i = getNode(endPosition)->getStepsNum(); i > 0; i--)
{
_path.push_back(pf->getPrevDir());
pf=pf->getPrevNode();
}
}
void Pathfinding::calculate(BattleUnit *unit, Position endPosition)
{
std::list<PathfindingNode*> openList;
PathfindingNode *currentNode, *nextNode;
Position currentPos, nextPos, startPosition = unit->getPosition();
int tuCost, totalTuCost = 0;
_movementType = unit->getUnit()->getArmor()->getMovementType();
_unit = unit;
Tile *destinationTile = _save->getTile(endPosition);
// check if destination is not blocked
if (isBlocked(destinationTile, MapData::O_FLOOR) || isBlocked(destinationTile, MapData::O_OBJECT)) return;
// the following check avoids that the unit walks behind the stairs if we click behind the stairs to make it go up the stairs.
// it only works if the unit is on one of the 2 tiles on the stairs, or on the tile right in front of the stairs.
if (isOnStairs(startPosition, endPosition))
{
endPosition.z++;
destinationTile = _save->getTile(endPosition);
}
// check if we have floor, else lower destination (for non flying units only, because otherwise they never reached this place)
while (canFallDown(destinationTile) && _movementType != MT_FLY)
{
endPosition.z--;
destinationTile = _save->getTile(endPosition);
}
_path.clear();
if (startPosition.z == endPosition.z && bresenhamPath(startPosition, endPosition))
return;
_path.clear();
// reset every node, so we have to check them all
for (int i = 0; i < _size; ++i)
_nodes[i]->reset();
// start position is the first one in our "open" list
openList.push_back(getNode(startPosition));
openList.front()->check(0, 0, 0, 0);
// if the open list is empty, we've reached the end
while(!openList.empty())
{
currentPos = openList.front()->getPosition();
currentNode = getNode(currentPos);
// this algorithm expands in all directions
for (int direction = 0; direction < 10; direction++)
{
tuCost = getTUCost(currentPos, direction, &nextPos, unit);
if(tuCost < 255) // check if we can go to this node (ie is not blocked)
{
nextNode = getNode(nextPos);
totalTuCost = currentNode->getTUCost() + tuCost;
// if we haven't checked this node, or the current cost tu cost is lower than our previous path, push this node in the open list to visit later.
if( (!nextNode->isChecked() || nextNode->getTUCost() > totalTuCost)
&& // this will keep pushing back nodes, as long as we did not reach the end position or there are still possible shorter paths
(!getNode(endPosition)->isChecked() || getNode(endPosition)->getTUCost() > totalTuCost)
)
{
nextNode->check(totalTuCost,
currentNode->getStepsNum() + 1,
currentNode,
direction);
openList.push_back(nextNode);
}
}
}
openList.pop_front();
}
if(!getNode(endPosition)->isChecked()) return;
//Backward tracking of the path
PathfindingNode* pf = getNode(endPosition);
for (int i = getNode(endPosition)->getStepsNum(); i > 0; i--)
{
_path.push_back(pf->getPrevDir());
pf=pf->getPrevNode();
}
}
