CCArray* PathPlanner::Calculate_A_Star(CCPoint source, CCPoint dest)
{
// bool isPathFound = false;
bool forceStop = false;
// 1. Insert the intial position in openList
ShortestPathStep* tmp = new ShortestPathStep(source);
tmp->autorelease();
this->InsertInOpenSteps(tmp);
do
{
// 1. get the Lowest F cost in the open list
//because the list is ordered, the lowest is the first
ShortestPathStep* currentStep = dynamic_cast<ShortestPathStep*>(mOpenSteps->objectAtIndex(0));
//2. Add the current in the closed list
mClosedSteps->addObject(currentStep);
//3. remove from the open list
mOpenSteps->removeObjectAtIndex(0);
//check if is the current = destination, we have DONE!
if(currentStep->GetTilePosition().equals(dest) )
{
// create the path and start the move action and animation
mOpenSteps->release();
this->mOpenSteps = NULL;
mClosedSteps->release();
this->mClosedSteps = NULL;
return this->constructPathAndStartAnimationFromStep(currentStep);
}
//4. Get adj tile coord of the current step
std::vector<CCPoint> tmpAdjArray = m_pLevelMap->GetWalkableAdjacentTiles(currentStep->GetTilePosition());
std::vector<CCPoint>::iterator iter;
for(iter = tmpAdjArray.begin(); iter < tmpAdjArray.end(); iter++)
{
CCPoint p = *iter;
ShortestPathStep* step = new ShortestPathStep(p);
// 4.1 // Check if the step isn't already in the closed set
CCObject* iterSteps;
CCARRAY_FOREACH(mClosedSteps, iterSteps)
{
ShortestPathStep *tmpStep = dynamic_cast<ShortestPathStep*>(iterSteps);
if(step->isEqualTile(tmpStep))
{
step->release();
forceStop = true;
break;
}
}
if(forceStop)
{
forceStop = false;
continue;
}
//4.2 //Compute the cost from the current to the step
int moveCost = CostToMoveFromStep(currentStep, step);
//4.3 //check if the step is already in the open list
//int indexStep = mOpenSteps->indexOfObject(step);
int indexStep = -1;
bool isPresent = false;
iterSteps = NULL;
CCARRAY_FOREACH(mOpenSteps, iterSteps)
{
indexStep++;
ShortestPathStep *tmpStep = dynamic_cast<ShortestPathStep*>(iterSteps);
if(step->isEqualTile(tmpStep))
{
isPresent = true;
break;
}
}
if(!isPresent)
{
//4.4 // Add it, set parent
step->SetParent(currentStep);
//4.5 // set the G score
step->SetGScore(currentStep->GetGScore() + moveCost);
//4.6 // compute the H score, with manhattan
step->SetHScore(this->ComputeH_Score(step->GetTilePosition(), dest));
//4.7 //now add in Open list, in correct position
this->InsertInOpenSteps(step);
//done, release the step
step->release();
}
else //already in the open list, recalculate the Fscore
{
step->release();
step = NULL;
//get the old step
step = dynamic_cast<ShortestPathStep*>(mOpenSteps->objectAtIndex(indexStep));
//5. Check if the old G score is lower than that step
if( (currentStep->GetGScore() + moveCost) < step->GetGScore())
{
//so we change the G score
step->SetGScore(currentStep->GetGScore() + moveCost);
// Because the G Score has changed, the F score may have changed too
// So to keep the open list ordered we have to remove the step, and re-insert it with
// the insert function which is preserving the list ordered by F score
// We have to retain it before removing it from the list
step->retain();
// Now we can removing it from the list without be afraid that it can be released
mOpenSteps->removeObjectAtIndex(indexStep);
// Re-insert it with the function which is preserving the list ordered by F score
this->InsertInOpenSteps(step);
step->release();
}
}
}
