80 lines
1.7 KiB
TypeScript
80 lines
1.7 KiB
TypeScript
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/**
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* A星尋路
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* @author BrightLi
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* @since 2020/4/18
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*/
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import Grid from "./Grid"
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import Node from "./Node"
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import BinaryHeap from "./BinaryHeap"
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export default class AStar
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{
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private _path:Array<Node>;
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private _clear:Array<Node>;
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constructor(){
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}
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// 開始導路
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public findPath(grid:Grid):Array<Node>{
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let endNode=grid.endNode;
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if(!grid.isWallableAt(endNode.x,endNode.y)){
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return [];
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}
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var startNode=grid.startNode;
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startNode.g=0;
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startNode.f=0;
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var endX=grid.endNode.x;
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var endY=grid.endNode.y;
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var openList=new BinaryHeap(function(node){
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return node.f;
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});
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openList.push(startNode);
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var closeList:Array<Node>=[];
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while(!openList.isEmpty){
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var node=openList.pop();
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closeList.push(node);
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if(node.x == endNode.x && node.y == endNode.y){
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var result=this.backtrace(node);
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// 清理節點
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for(node of closeList){
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node.clear();
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}
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return result;
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}
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var neighbors=grid.getNeighbors(node,1);
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for(var neighbor of neighbors){
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var closed=(closeList.indexOf(neighbor) != -1);
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if(closed){
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continue;
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}
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var x=neighbor.x;
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var y=neighbor.y;
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var ng=node.g+((x-node.x==0 || y-node.y==0) ?1:1.414);
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var opened=openList.contain(neighbor);
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if(!opened || ng<neighbor.g){
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neighbor.g=ng;
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neighbor.h=neighbor.h || Math.abs(x-endX)+Math.abs(y-endY);
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neighbor.f=neighbor.g+neighbor.h;
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neighbor.parent=node
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if(!opened){
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openList.push(neighbor);
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}else{
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openList.update(neighbor);
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}
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}
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}
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}
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return [];
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}
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// 生成導航路徑
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private backtrace(node:Node):Array<Node>{
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var path=[node];
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while(node.parent){
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node=node.parent;
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path.push(node);
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}
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return path.reverse();
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}
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}
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