337 lines
7.8 KiB
C++
337 lines
7.8 KiB
C++
// ==============================================================
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// This file is part of Glest (www.glest.org)
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//
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// Copyright (C) 2001-2008 Martio Figueroa
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//
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// You can redistribute this code and/or modify it under
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// the terms of the GNU General Public License as published
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// by the Free Software Foundation; either version 2 of the
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// License, or (at your option) any later version
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// ==============================================================
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#include "path_finder.h"
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#include <algorithm>
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#include <cassert>
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#include "config.h"
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#include "map.h"
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#include "unit.h"
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#include "unit_type.h"
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#include "leak_dumper.h"
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using namespace std;
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using namespace Shared::Graphics;
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using namespace Shared::Util;
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namespace Glest{ namespace Game{
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// =====================================================
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// class PathFinder
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// =====================================================
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// ===================== PUBLIC ========================
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const int PathFinder::maxFreeSearchRadius= 10;
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const int PathFinder::pathFindNodesMax= 400;
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const int PathFinder::pathFindRefresh= 10;
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PathFinder::PathFinder(){
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nodePool= NULL;
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}
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PathFinder::PathFinder(const Map *map){
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init(map);
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nodePool= NULL;
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}
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void PathFinder::init(const Map *map){
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nodePool= new Node[pathFindNodesMax];
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this->map= map;
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}
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PathFinder::~PathFinder(){
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delete [] nodePool;
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}
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TravelState PathFinder::findPath(Unit *unit, const Vec2i &finalPos){
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//route cache
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UnitPathInterface *path= unit->getPath();
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if(finalPos==unit->getPos()) {
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//if arrived
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unit->setCurrSkill(scStop);
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return tsArrived;
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}
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else {
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if(dynamic_cast<UnitPathBasic *>(path) != NULL) {
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if(!path->isEmpty()) {
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//route cache
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Vec2i pos= path->pop();
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if(map->canMove(unit, unit->getPos(), pos)) {
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unit->setTargetPos(pos);
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return tsOnTheWay;
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}
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}
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}
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else if(dynamic_cast<UnitPath *>(path) != NULL) {
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UnitPath *advPath = dynamic_cast<UnitPath *>(path);
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if(advPath->isEmpty() == false) {
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//route cache
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Vec2i pos= advPath->peek();
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if(map->canMove(unit, unit->getPos(), pos)){
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path->pop();
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unit->setTargetPos(pos);
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return tsOnTheWay;
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}
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}
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}
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}
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//route cache miss
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TravelState ts= aStar(unit, finalPos);
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//post actions
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switch(ts){
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case tsBlocked:
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case tsArrived:
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unit->setCurrSkill(scStop);
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break;
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case tsOnTheWay:
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{
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if(dynamic_cast<UnitPathBasic *>(path) != NULL) {
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Vec2i pos= path->pop();
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if(map->canMove(unit, unit->getPos(), pos)) {
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unit->setTargetPos(pos);
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}
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else {
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unit->setCurrSkill(scStop);
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return tsBlocked;
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}
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}
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else if(dynamic_cast<UnitPath *>(path) != NULL) {
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UnitPath *advPath = dynamic_cast<UnitPath *>(path);
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Vec2i pos= advPath->peek();
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if(map->canMove(unit, unit->getPos(), pos)) {
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advPath->pop();
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unit->setTargetPos(pos);
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}
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else {
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unit->setCurrSkill(scStop);
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return tsBlocked;
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}
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}
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}
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break;
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}
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return ts;
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}
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// ==================== PRIVATE ====================
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//route a unit using A* algorithm
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TravelState PathFinder::aStar(Unit *unit, const Vec2i &targetPos){
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nodePoolCount= 0;
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const Vec2i finalPos= computeNearestFreePos(unit, targetPos);
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//if arrived
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if(finalPos==unit->getPos()){
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return tsArrived;
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}
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//path find algorithm
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//a) push starting pos into openNodes
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Node *firstNode= newNode();
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assert(firstNode!=NULL);;
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firstNode->next= NULL;
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firstNode->prev= NULL;
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firstNode->pos= unit->getPos();
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firstNode->heuristic= heuristic(unit->getPos(), finalPos);
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firstNode->exploredCell= true;
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openNodes.push_back(firstNode);
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//b) loop
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bool pathFound= true;
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bool nodeLimitReached= false;
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Node *node= NULL;
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while(!nodeLimitReached){
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//b1) is open nodes is empty => failed to find the path
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if(openNodes.empty()){
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pathFound= false;
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break;
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}
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//b2) get the minimum heuristic node
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Nodes::iterator it = minHeuristic();
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node= *it;
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//b3) if minHeuristic is the finalNode, or the path is no more explored => path was found
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if(node->pos==finalPos || !node->exploredCell){
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pathFound= true;
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break;
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}
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//b4) move this node from closedNodes to openNodes
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//add all succesors that are not in closedNodes or openNodes to openNodes
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closedNodes.push_back(node);
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openNodes.erase(it);
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for(int i=-1; i<=1 && !nodeLimitReached; ++i){
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for(int j=-1; j<=1 && !nodeLimitReached; ++j){
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Vec2i sucPos= node->pos + Vec2i(i, j);
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if(!openPos(sucPos) && map->aproxCanMove(unit, node->pos, sucPos)){
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//if node is not open and canMove then generate another node
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Node *sucNode= newNode();
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if(sucNode!=NULL){
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sucNode->pos= sucPos;
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sucNode->heuristic= heuristic(sucNode->pos, finalPos);
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sucNode->prev= node;
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sucNode->next= NULL;
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sucNode->exploredCell= map->getSurfaceCell(Map::toSurfCoords(sucPos))->isExplored(unit->getTeam());
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openNodes.push_back(sucNode);
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}
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else{
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nodeLimitReached= true;
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}
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}
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}
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}
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}//while
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Node *lastNode= node;
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//if consumed all nodes find best node (to avoid strage behaviour)
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if(nodeLimitReached){
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for(Nodes::iterator it= closedNodes.begin(); it!=closedNodes.end(); ++it){
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if((*it)->heuristic < lastNode->heuristic){
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lastNode= *it;
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}
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}
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}
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//check results of path finding
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TravelState ts;
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UnitPathInterface *path= unit->getPath();
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if(pathFound==false || lastNode==firstNode){
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//blocked
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ts= tsBlocked;
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path->incBlockCount();
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}
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else {
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//on the way
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ts= tsOnTheWay;
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//build next pointers
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Node *currNode= lastNode;
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while(currNode->prev!=NULL){
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currNode->prev->next= currNode;
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currNode= currNode->prev;
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}
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//store path
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path->clear();
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currNode= firstNode;
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for(int i=0; currNode->next!=NULL && i<pathFindRefresh; currNode= currNode->next, i++){
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path->push(currNode->next->pos);
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}
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}
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//clean nodes
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openNodes.clear();
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closedNodes.clear();
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return ts;
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}
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PathFinder::Node *PathFinder::newNode(){
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if(nodePoolCount<pathFindNodesMax){
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Node *node= &nodePool[nodePoolCount];
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nodePoolCount++;
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return node;
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}
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return NULL;
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}
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Vec2i PathFinder::computeNearestFreePos(const Unit *unit, const Vec2i &finalPos){
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//unit data
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Vec2i unitPos= unit->getPos();
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int size= unit->getType()->getSize();
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Field field= unit->getCurrField();
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int teamIndex= unit->getTeam();
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//if finalPos is free return it
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if(map->isAproxFreeCells(finalPos, size, field, teamIndex)){
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return finalPos;
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}
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//find nearest pos
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Vec2i nearestPos= unitPos;
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float nearestDist= unitPos.dist(finalPos);
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for(int i= -maxFreeSearchRadius; i<=maxFreeSearchRadius; ++i){
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for(int j= -maxFreeSearchRadius; j<=maxFreeSearchRadius; ++j){
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Vec2i currPos= finalPos + Vec2i(i, j);
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if(map->isAproxFreeCells(currPos, size, field, teamIndex)){
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float dist= currPos.dist(finalPos);
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//if nearer from finalPos
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if(dist<nearestDist){
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nearestPos= currPos;
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nearestDist= dist;
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}
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//if the distance is the same compare distance to unit
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else if(dist==nearestDist){
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if(currPos.dist(unitPos)<nearestPos.dist(unitPos)){
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nearestPos= currPos;
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}
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}
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}
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}
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}
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return nearestPos;
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}
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float PathFinder::heuristic(const Vec2i &pos, const Vec2i &finalPos){
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return pos.dist(finalPos);
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}
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//returns an iterator to the lowest heuristic node
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PathFinder::Nodes::iterator PathFinder::minHeuristic(){
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Nodes::iterator minNodeIt= openNodes.begin();
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assert(!openNodes.empty());
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for(Nodes::iterator it= openNodes.begin(); it!=openNodes.end(); ++it){
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if((*it)->heuristic < (*minNodeIt)->heuristic){
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minNodeIt= it;
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}
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}
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return minNodeIt;
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}
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bool PathFinder::openPos(const Vec2i &sucPos){
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for(Nodes::reverse_iterator it= closedNodes.rbegin(); it!=closedNodes.rend(); ++it){
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if(sucPos==(*it)->pos){
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return true;
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}
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}
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//use reverse iterator to find a node faster
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for(Nodes::reverse_iterator it= openNodes.rbegin(); it!=openNodes.rend(); ++it){
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if(sucPos==(*it)->pos){
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return true;
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}
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}
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return false;
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}
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}} //end namespace
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