Code:
#include <iostream>
#include <iomanip>
#include <queue>
#include <string>
#include <math.h>
#include <ctime>
#include <stdio.h>
#include <stdlib.h>
using namespace std;
const int n=60; // horizontal size of the map
const int m=60; // vertical size size of the map
const int rot=8;
const double translationalIncrement = 0.1; // *meter
const double rotationalIncrement = 0.785; //*radian
const double rot2transConstant = 0.471; // meter/radian
static int map[n][m][rot];
static int closed_nodes_map[n][m][rot]; // map of closed (tried-out) nodes
static int open_nodes_map[n][m][rot]; // map of open (not-yet-tried) nodes
static int dir_map[n][m][rot]; // map of directions
const int dir=26; // number of possible directions to go at any position
// if dir==4
//static int dx[dir]={1, 0, -1, 0};
//static int dy[dir]={0, 1, 0, -1};
// if dir==8
static int dx[dir]={1, 1, 0, -1, -1, -1, 0, 1, 0, 1, 1, 0, -1, -1, -1, 0, 1, 0, 1, 1, 0, -1, -1, -1, 0, 1};
static int dy[dir]={0, 1, 1, 1, 0, -1, -1, -1, 0, 0, 1, 1, 1, 0, -1, -1, -1, 0, 0, 1, 1, 1, 0, -1, -1, -1};
static int aphi[dir]={0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1, -1};
class node
{
// current position
int xPos;
int yPos;
int phiAngle;
// total distance already travelled to reach the node
int level;
// priority=level+remaining distance estimate
int priority; // smaller: higher priority
public:
node(int xp, int yp, int phia, int d, int p)
{xPos=xp; yPos=yp; phiAngle=phia; level=d; priority=p;}
int getxPos() const {return xPos;}
int getyPos() const {return yPos;}
int getphiAngle() const {return phiAngle;}
int getLevel() const {return level;}
int getPriority() const {return priority;}
void updatePriority(const int & xDest, const int & yDest, const int & phiDest)
{
priority=level+estimate(xDest, yDest, phiDest)*10; //A*
}
// give better priority to going strait instead of diagonally
void nextLevel(const int & i) // i: direction
{
level += (int) sqrt( pow(dx[i]*translationalIncrement, 2.0) + pow(dy[i]*translationalIncrement, 2.0) + pow(aphi[i]*rotationalIncrement * rot2transConstant, 2.0));
}
// Estimation function for the remaining distance to the goal.
const int & estimate(const int & xDest, const int & yDest, const int & phiDest) const
{
static int xd, yd, phid, d;
xd=xDest-xPos;
yd=yDest-yPos;
phid=phiDest-phiAngle;
// Euclidian Distance
d=static_cast<int>(sqrt(xd*xd+yd*yd+phid*phid));
// Manhattan distance
//d=abs(xd)+abs(yd);
// Chebyshev distance
//d=max(abs(xd), abs(yd));
return(d);
}
};
// Determine priority (in the priority queue)
bool operator<(const node & a, const node & b)
{
return a.getPriority() > b.getPriority();
}
// A-star algorithm.
// The route returned is a string of direction digits.
string pathFind( const int & xStart, const int & yStart, const int & phiStart,
const int & xFinish, const int & yFinish, const int & phiFinish )
{
static priority_queue<node> pq[2]; // list of open (not-yet-tried) nodes
static int pqi; // pq index
static node* n0;
static node* m0;
static int i, j, x, y, phi, xdx, ydy, phidphi;
static char c;
pqi=0;
// reset the node maps
for(phi=0;phi<rot;phi++)
{
for(y=0;y<m;y++)
{
for(x=0;x<n;x++)
{
closed_nodes_map[x][y][phi]=0;
open_nodes_map[x][y][phi]=0;
}
}
}
// create the start node and push into list of open nodes
n0=new node(xStart, yStart, phiStart, 0, 0);
n0->updatePriority(xFinish, yFinish, phiFinish);
pq[pqi].push(*n0);
open_nodes_map[x][y][phi]=n0->getPriority(); // mark it on the open nodes map
// A* search
while(!pq[pqi].empty())
{
// get the current node w/ the highest priority
// from the list of open nodes
n0=new node( pq[pqi].top().getxPos(), pq[pqi].top().getyPos(), pq[pqi].top().getphiAngle(),
pq[pqi].top().getLevel(), pq[pqi].top().getPriority());
x=n0->getxPos();
y=n0->getyPos();
phi=n0->getphiAngle();
pq[pqi].pop(); // remove the node from the open list
open_nodes_map[x][y][phi]=0;
// mark it on the closed nodes map
closed_nodes_map[x][y][phi]=1;
// quit searching when the goal state is reached
//if((*n0).estimate(xFinish, yFinish) == 0)
if(x==xFinish && y==yFinish && phi==phiFinish)
{
// generate the path from finish to start
// by following the directions
string path="";
while(!(x==xStart && y==yStart && phi==phiStart))
{
j=dir_map[x][y][phi];
c='0'+(j+dir/2)%dir;
path=c+path;
x+=dx[j];
y+=dy[j];
phi+=aphi[j];
}
// garbage collection
delete n0;
// empty the leftover nodes
while(!pq[pqi].empty()) pq[pqi].pop();
return path;
}
// generate moves (child nodes) in all possible directions
for(i=0;i<dir;i++)
{
xdx=x+dx[i];
ydy=y+dy[i];
phidphi=phi+aphi[i];
if(!(xdx<0 || xdx>n-1 || ydy<0 || ydy>m-1 || phidphi<0 || phidphi>rot-1 || map[xdx][ydy][phidphi]==1
|| closed_nodes_map[xdx][ydy][phidphi]==1))
{
// generate a child node
m0=new node( xdx, ydy, phidphi, n0->getLevel(),
n0->getPriority());
m0->nextLevel(i);
m0->updatePriority(xFinish, yFinish, phiFinish);
// if it is not in the open list then add into that
if(open_nodes_map[xdx][ydy][phidphi]==0)
{
open_nodes_map[xdx][ydy][phidphi]=m0->getPriority();
pq[pqi].push(*m0);
// mark its parent node direction
dir_map[xdx][ydy][phidphi]=(i+dir/2)%dir;
}
else if(open_nodes_map[xdx][ydy][phidphi]>m0->getPriority())
{
// update the priority info
open_nodes_map[xdx][ydy][phidphi]=m0->getPriority();
// update the parent direction info
dir_map[xdx][ydy][phidphi]=(i+dir/2)%dir;
// replace the node
// by emptying one pq to the other one
// except the node to be replaced will be ignored
// and the new node will be pushed in instead
while(!(pq[pqi].top().getxPos()==xdx &&
pq[pqi].top().getyPos()==ydy && pq[pqi].top().getphiAngle()==phidphi))
{
pq[1-pqi].push(pq[pqi].top());
pq[pqi].pop();
}
pq[pqi].pop(); // remove the wanted node
// empty the larger size pq to the smaller one
if(pq[pqi].size()>pq[1-pqi].size()) pqi=1-pqi;
while(!pq[pqi].empty())
{
pq[1-pqi].push(pq[pqi].top());
pq[pqi].pop();
}
pqi=1-pqi;
pq[pqi].push(*m0); // add the better node instead
}
else delete m0; // garbage collection
}
}
delete n0; // garbage collection
}
return ""; // no route found
}
int main()
{
srand(time(NULL));
// create empty map
for(int phi=0;phi<rot;phi++)
{
for(int y=0;y<m;y++)
{
for(int x=0;x<n;x++)
map[x][y][phi]=0;
}
}
// fillout the map matrix with a '+' pattern
for(int phi=0;phi<rot;phi++)
{
for(int x=n/8;x<n*7/8;x++)
{
map[x][m/2][phi]=1;
}
for(int y=m/8;y<m*7/8;y++)
{
map[n/2][y][phi]=1;
}
}
// randomly select start and finish locations
int xA, yA, phiA, xB, yB, phiB;
switch(rand()%2)
{
case 0: xA=0;yA=0;phiA=0;xB=n-1;yB=m-1;phiB=rot-1; break;
case 1: xA=0;yA=m-1;xB=n-1;yB=0;phiA=0;phiB=rot-1; break;
/* case 2: xA=n/2-1;yA=m/2-1;xB=n/2+1;yB=m/2+1; break;
case 3: xA=n/2-1;yA=m/2+1;xB=n/2+1;yB=m/2-1; break;
case 4: xA=n/2-1;yA=0;xB=n/2+1;yB=m-1; break;
case 5: xA=n/2+1;yA=m-1;xB=n/2-1;yB=0; break;
case 6: xA=0;yA=m/2-1;xB=n-1;yB=m/2+1; break;
case 7: xA=n-1;yA=m/2+1;xB=0;yB=m/2-1; break; */
}
cout<<"Map Size (X,Y,Phi): "<<n<<","<<m<<","<<rot<<endl;
cout<<"Start: "<<xA<<","<<yA<<","<<phiA<<endl;
cout<<"Finish: "<<xB<<","<<yB<<","<<phiB<<endl;
// get the route
clock_t start = clock();
string route=pathFind(xA, yA, phiA, xB, yB, phiB);
if(route=="") cout<<"An empty route generated!"<<endl;
clock_t end = clock();
double time_elapsed = double(end - start);
cout<<"Time to calculate the route (ms): "<<time_elapsed<<endl;
cout<<"Route:"<<endl;
cout<<route<<endl<<endl;
// follow the route on the map and display it
if(route.length()>0)
{
int j; char c;
int x=xA;
int y=yA;
int phi=phiA;
map[x][y][phi]=2;
for(int i=0;i<route.length();i++)
{
c =route.at(i);
j=atoi(&c);
x=x+dx[j];
y=y+dy[j];
phi=phi+aphi[j];
map[x][y][phi]=3;
}
map[x][y][phi]=4;
// display the map with the route
for(phi=0;phi<rot;phi++)
{
for(int y=0;y<m;y++)
{
for(int x=0;x<n;x++)
if(map[x][y][phi]==0)
cout<<".";
else if(map[x][y][phi]==1)
cout<<"O"; //obstacle
else if(map[x][y][phi]==2)
cout<<"S"; //start
else if(map[x][y][phi]==3)
cout<<"R"; //route
else if(map[x][y][phi]==4)
cout<<"F"; //finish
cout<<endl;
}
}
}
getchar(); // wait for a (Enter) keypress
return(0);
}
