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authorEugenio Favalli <elvenprogrammer@gmail.com>2004-09-26 13:08:46 +0000
committerEugenio Favalli <elvenprogrammer@gmail.com>2004-09-26 13:08:46 +0000
commit92bbeab96bf61edf9b7caa125ed67e634258383e (patch)
treea95dd426590c8e6208445290fa8b9b47c1a57bcb /src/astar.cpp
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+#include "astar.h"
+#include "being.h"
+
+const int numberPeople = 1;
+ int onClosedList = 10;
+ const int notfinished = 0;// path-related constants
+
+ //Create needed arrays
+ //char get_path_walk [MAP_WIDTH][MAP_HEIGHT];
+ int openList[MAP_WIDTH*MAP_HEIGHT+2]; //1 dimensional array holding ID# of open list items
+ int whichList[MAP_WIDTH+1][MAP_HEIGHT+1]; //2 dimensional array used to record
+// whether a cell is on the open list or on the closed list.
+ int openX[MAP_WIDTH*MAP_HEIGHT+2]; //1d array stores the x location of an item on the open list
+ int openY[MAP_WIDTH*MAP_HEIGHT+2]; //1d array stores the y location of an item on the open list
+ int parentX[MAP_WIDTH+1][MAP_HEIGHT+1]; //2d array to store parent of each cell (x)
+ int parentY[MAP_WIDTH+1][MAP_HEIGHT+1]; //2d array to store parent of each cell (y)
+ int F_cost[MAP_WIDTH*MAP_HEIGHT+2]; //1d array to store F cost of a cell on the open list
+ int G_cost[MAP_WIDTH+1][MAP_HEIGHT+1]; //2d array to store G_cost cost for each cell.
+ int H_cost[MAP_WIDTH*MAP_HEIGHT+2]; //1d array to store H cost of a cell on the open list
+ int pathLength; //stores length of the FOUND path for critter
+ int pathLocation; //stores current position along the chosen path for critter
+ int* path_bank ;
+
+ //Path reading variables
+ int pathStatus;
+ int xPath;
+ int yPath;
+
+/** Initialize pathfinder */
+void pathfinder_init() {
+ path_bank = (int*)malloc(4);
+}
+
+/** Exit pathfinder */
+void pathfinder_exit() {
+ free(path_bank);
+}
+
+/** Find path */
+PATH_NODE *find_path(int pathfinderID, int s_x, int s_y, int e_x, int e_y) {
+ int onOpenList=0, parentXval=0, parentYval=0,
+ a=0, b=0, m=0, u=0, v=0, temp=0, corner=0, numberOfOpenListItems=0,
+ addedGCost=0, tempG = 0, path = 0, x=0, y=0,
+ tempx, pathX, pathY, cellPosition,
+ newOpenListItemID=0;
+
+ // If starting location and target are in the same location...
+ if (s_x==e_x && s_y==e_y && pathLocation>0)return NULL;
+ else if (s_x==e_x && s_y==e_y && pathLocation==0)return NULL;
+
+ // If dest tile is NOT_WALKABLE, return that it's a NOT_FOUND path.
+ if(get_path_walk(e_x, e_y)==NOT_WALKABLE) {
+ xPath = s_x;
+ yPath = s_y;
+ return NULL;
+ }
+
+ // Reset some variables that need to be cleared
+ for(x=0;x<MAP_WIDTH;x++) {
+ for(y=0;y<MAP_HEIGHT;y++)
+ whichList [x][y] = 0;
+ }
+ onClosedList = 2; //changing the values of onOpenList and onClosed list is faster than redimming whichList() array
+ onOpenList = 1;
+ pathLength = NOT_STARTED;
+ pathLocation = NOT_STARTED;
+ G_cost[s_x][s_y] = 0; //reset starting square's G_cost value to 0
+
+ // Add the starting location to the open list of tiles to be checked.
+ numberOfOpenListItems = 1;
+ openList[1] = 1;//assign it as the top (and currently only) item in the open list, which is maintained as a binary heap (explained below)
+ openX[1] = s_x ; openY[1] = s_y;
+
+ // Do the following until a path is FOUND or deemed NOT_FOUND.
+ do {
+
+ // If the open list is not empty, take the first cell off of the list.
+ // This is the lowest F cost cell on the open list.
+ if (numberOfOpenListItems != 0) {
+
+ // Pop the first item off the open list.
+ parentXval = openX[openList[1]];
+ parentYval = openY[openList[1]]; //record cell coordinates of the item
+ whichList[parentXval][parentYval] = onClosedList;//add the item to the closed list
+
+ // Open List = Binary Heap: Delete this item from the open list, which
+ numberOfOpenListItems = numberOfOpenListItems - 1;//reduce number of open list items by 1
+
+ // Delete the top item in binary heap and reorder the heap, with the lowest F cost item rising to the top.
+ openList[1] = openList[numberOfOpenListItems+1];//move the last item in the heap up to slot #1
+ v = 1;
+
+ // Repeat the following until the new item in slot #1 sinks to its proper spot in the heap.
+ do {
+ u = v;
+ if (2*u+1 <= numberOfOpenListItems) { //if both children exist
+ //Check if the F cost of the parent is greater than each child.
+ //Select the lowest of the two children.
+ if(F_cost[openList[u]] >= F_cost[openList[2*u]])v = 2*u;
+ if(F_cost[openList[v]] >= F_cost[openList[2*u+1]])v = 2*u+1;
+ } else {
+ if (2*u <= numberOfOpenListItems) { //if only child #1 exists
+ //Check if the F cost of the parent is greater than child #1
+ if (F_cost[openList[u]] >= F_cost[openList[2*u]])v = 2*u;
+ }
+ }
+
+ if (u!=v) { // if parent's F is > one of its children, swap them
+ temp = openList[u];
+ openList[u] = openList[v];
+ openList[v] = temp;
+ } else break; //otherwise, exit loop
+ } while (u!=v); //reorder the binary heap
+
+
+// Check the adjacent squares. (Its "children" -- these path children
+// are similar, conceptually, to the binary heap children mentioned
+// above, but don't confuse them. They are different. Path children
+// are portrayed in Demo 1 with grey pointers pointing toward
+// their parents.) Add these adjacent child squares to the open list
+// for later consideration if appropriate (see various if statements
+// below).
+
+ for(b=parentYval-1;b<=parentYval+1;b++) {
+ for(a=parentXval-1;a<=parentXval+1;a++) {
+ // If not off the map (do this first to avoid array out-of-bounds errors)
+ if(a!=-1 && b!=-1 && a!=MAP_WIDTH && b!=MAP_HEIGHT) {
+ // If not already on the closed list (items on the closed list have
+ // already been considered and can now be ignored).
+ if(whichList[a][b]!=onClosedList) {
+ // If not a wall/obstacle square.
+ if (get_path_walk(a, b)!=NOT_WALKABLE) {
+ // Don't cut across corners
+ corner = WALKABLE;
+ if(a==parentXval-1) {
+ if(b==parentYval-1) {
+ if(get_path_walk(parentXval-1, parentYval)==NOT_WALKABLE || get_path_walk(parentXval, parentYval-1)==NOT_WALKABLE) // cera slash
+ corner = NOT_WALKABLE;
+ } else if (b==parentYval+1) {
+ if(get_path_walk(parentXval, parentYval+1)==NOT_WALKABLE || get_path_walk(parentXval-1, parentYval)==NOT_WALKABLE)
+ corner = NOT_WALKABLE;
+ }
+ } else if(a==parentXval+1) {
+ if(b==parentYval-1) {
+ if(get_path_walk(parentXval, parentYval-1)==NOT_WALKABLE || get_path_walk(parentXval+1, parentYval)==NOT_WALKABLE)
+ corner = NOT_WALKABLE;
+ } else if(b==parentYval+1) {
+ if(get_path_walk(parentXval+1, parentYval)==NOT_WALKABLE || get_path_walk(parentXval, parentYval+1)==NOT_WALKABLE)
+ corner = NOT_WALKABLE;
+ }
+ }
+
+ if(corner==WALKABLE) {
+ // If not already on the open list, add it to the open list.
+ if (whichList[a][b]!=onOpenList) {
+ // Create a new open list item in the binary heap.
+ newOpenListItemID = newOpenListItemID + 1; //each new item has a unique ID #
+ m = numberOfOpenListItems+1;
+ openList[m] = newOpenListItemID;//place the new open list item (actually, its ID#) at the bottom of the heap
+ openX[newOpenListItemID] = a;
+ openY[newOpenListItemID] = b;//record the x and y coordinates of the new item
+
+ //Figure out its G_cost cost
+ if (abs(a-parentXval) == 1 && abs(b-parentYval) == 1)addedGCost = 14;//cost of going to diagonal squares
+ else addedGCost = 10;//cost of going to non-diagonal squares
+ G_cost[a][b] = G_cost[parentXval][parentYval] + addedGCost;
+
+ //Figure out its H and F costs and parent
+ H_cost[openList[m]] = 10*(abs(a - e_x) + abs(b - e_y));
+ F_cost[openList[m]] = G_cost[a][b] + H_cost[openList[m]];
+ parentX[a][b] = parentXval ; parentY[a][b] = parentYval;
+
+ //Move the new open list item to the proper place in the binary heap.
+ //Starting at the bottom, successively compare to parent items,
+ //swapping as needed until the item finds its place in the heap
+ //or bubbles all the way to the top (if it has the lowest F cost).
+ while(m!=1) { // While item hasn't bubbled to the top (m=1)
+ //Check if child's F cost is < parent's F cost. If so, swap them.
+ if(F_cost[openList[m]]<=F_cost[openList[m/2]]) {
+ temp = openList[m/2];
+ openList[m/2] = openList[m];
+ openList[m] = temp;
+ m = m/2;
+ } else break;
+ }
+
+ numberOfOpenListItems = numberOfOpenListItems+1;//add one to the number of items in the heap
+ //Change whichList to show that the new item is on the open list.
+ whichList[a][b] = onOpenList;
+ } else { // If whichList(a,b) = onOpenList
+ // If adjacent cell is already on the open list, check to see if this
+ // path to that cell from the starting location is a better one.
+ // If so, change the parent of the cell and its G_cost and F costs.
+ //Figure out the G_cost cost of this possible new path
+ if(abs(a-parentXval)==1 && abs(b-parentYval)==1)addedGCost = 14;//cost of going to diagonal tiles
+ else addedGCost = 10;//cost of going to non-diagonal tiles
+
+ tempG = G_cost[parentXval][parentYval] + addedGCost;
+
+ // If this path is shorter (G_cost cost is lower) then change
+ // the parent cell, G_cost cost and F cost.
+ if(tempG<G_cost[a][b]) { //if G_cost cost is less,
+ parentX[a][b] = parentXval; //change the square's parent
+ parentY[a][b] = parentYval;
+ G_cost[a][b] = tempG;//change the G_cost cost
+
+ // Because changing the G_cost cost also changes the F cost, if
+ // the item is on the open list we need to change the item's
+ // recorded F cost and its position on the open list to make
+ // sure that we maintain a properly ordered open list.
+
+ for(int x=1;x<=numberOfOpenListItems;x++) { //look for the item in the heap
+ if(openX[openList[x]]==a && openY[openList[x]]==b) { //item FOUND
+ F_cost[openList[x]] = G_cost[a][b] + H_cost[openList[x]];//change the F cost
+ //See if changing the F score bubbles the item up from it's current location in the heap
+ m = x;
+ while(m!=1) { //While item hasn't bubbled to the top (m=1)
+ //Check if child is < parent. If so, swap them.
+ if(F_cost[openList[m]]<F_cost[openList[m/2]]) {
+ temp = openList[m/2];
+ openList[m/2] = openList[m];
+ openList[m] = temp;
+ m = m/2;
+ } else break;
+ }
+ break; //exit for x = loop
+ } // If openX(openList(x)) = a
+ } // For x = 1 To numberOfOpenListItems
+ } // If tempG < G_cost(a,b)
+ } // else If whichList(a,b) = onOpenList
+ } // If not cutting a corner
+ } // If not a wall/obstacle square.
+ } // If not already on the closed list
+ } // If not off the map
+ } // for (a = parentXval-1; a <= parentXval+1; a++){
+ } // for (b = parentYval-1; b <= parentYval+1; b++){
+ } else {// if (numberOfOpenListItems != 0)
+ // If open list is empty then there is no path.
+ path = NOT_FOUND;
+ break;
+ }
+ //If target is added to open list then path has been FOUND.
+ if (whichList[e_x][e_y]==onOpenList) {
+ path = FOUND;
+ break;
+ }
+
+ } while (path!=FOUND && path!=NOT_FOUND);//Do until path is FOUND or deemed NOT_FOUND
+
+ // Save the path if it exists.
+ if (path == FOUND) {
+
+ // Working backwards from the target to the starting location by checking
+ // each cell's parent, figure out the length of the path.
+ pathX = e_x; pathY = e_y;
+ do {
+ //Look up the parent of the current cell.
+ tempx = parentX[pathX][pathY];
+ pathY = parentY[pathX][pathY];
+ pathX = tempx;
+
+ //Figure out the path length
+ pathLength = pathLength + 1;
+ } while (pathX != s_x || pathY != s_y);
+
+ // Resize the data bank to the right size in bytes
+ path_bank = (int*) realloc (path_bank, pathLength*8);
+
+ // Now copy the path information over to the databank. Since we are
+ // working backwards from the target to the start location, we copy
+ // the information to the data bank in reverse order. The result is
+ // a properly ordered set of path data, from the first step to the last.
+ pathX = e_x ; pathY = e_y;
+ cellPosition = pathLength*2;//start at the end
+ do {
+ cellPosition = cellPosition - 2;//work backwards 2 integers
+ path_bank [cellPosition] = pathX;
+ path_bank [cellPosition+1] = pathY;
+ // Look up the parent of the current cell.
+ tempx = parentX[pathX][pathY];
+ pathY = parentY[pathX][pathY];
+ pathX = tempx;
+ // If we have reached the starting square, exit the loop.
+ } while(pathX!=s_x || pathY!=s_y);
+
+ char stringa[80];
+ sprintf(stringa,"%i %i",s_x,s_y);
+
+ PATH_NODE *ret = NULL, *temp = NULL;
+ pathLocation = 1;
+ ret = create_path_node(s_x,s_y);
+ temp = ret;
+ //alert(stringa,"","","","",0,0);
+ while(pathLocation<pathLength) {
+ sprintf(stringa,"%i %i",path_bank[pathLocation*2-2], path_bank[pathLocation*2-1]);
+ //alert(stringa,"","","","",0,0);
+ temp->next = create_path_node(path_bank[pathLocation*2-2], path_bank[pathLocation*2-1]);
+ if(temp->next==NULL)ok("Error", "Unable to create path node");
+ temp = temp->next;
+ pathLocation++;
+ }
+ if(temp!=NULL)temp->next = create_path_node(e_x, e_y);
+ else ok("Error", "Null reference");
+ return ret;
+
+ }
+ return NULL; // Path not found
+}
+
+
+
+/** Read the path data */
+void ReadPath(int pathfinderID) {
+ //If a path exists, read the path data
+ // from the pathbank.
+ pathLocation = 1; //set pathLocation to 1st step
+ while (pathLocation<pathLength) {
+ int a = path_bank [pathLocation*2-2];
+ int b = path_bank [pathLocation*2-1];
+ pathLocation = pathLocation + 1;
+ whichList[a][b] = 3;//draw dotted path
+ }
+}
+
+
+