#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 = new 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 = new 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 = new 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 } }