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JumpPointFinderBase.js
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JumpPointFinderBase.js
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var Heap = require('heap');
var Util = require('../core/Util');
var Heuristic = require('../core/Heuristic');
var DiagonalMovement = require('../core/DiagonalMovement');
/**
* Base class for the Jump Point Search algorithm
* @param {object} opt
* @param {function} opt.heuristic Heuristic function to estimate the distance
* (defaults to manhattan).
*/
function JumpPointFinderBase(opt) {
opt = opt || {};
this.heuristic = opt.heuristic || Heuristic.manhattan;
this.trackJumpRecursion = opt.trackJumpRecursion || false;
console.log("recursion",this.trackJumpRecursion)
}
/**
* Find and return the path.
* @return {Array<Array<number>>} The path, including both start and
* end positions.
*/
JumpPointFinderBase.prototype.findPath = function(startX, startY, endX, endY, grid) {
// console.log("JumpPoint1");
var openList = this.openList = new Heap(function(nodeA, nodeB) {
return nodeA.f - nodeB.f;
}),
startNode = this.startNode = grid.getNodeAt(startX, startY),
endNode = this.endNode = grid.getNodeAt(endX, endY), node;
this.grid = grid;
var operations = [];
// set the `g` and `f` value of the start node to be 0
startNode.g = 0;
startNode.f = 0;
// push the start node into the open list
openList.push(startNode);
startNode.opened = true;
operations.push({
x: startNode.x,
y: startNode.y,
attr: 'opened',
value: true
})
// while the open list is not empty
while (!openList.empty()) {
// pop the position of node which has the minimum `f` value.
node = openList.pop();
node.closed = true;
operations.push({
x: node.x,
y: node.y,
attr: 'closed',
value: true
})
if (node === endNode) {
res = {
path : Util.expandPath(Util.backtrace(endNode,operations)['path']),
operations : operations
}
// console.log(res)
return res
// return Util.expandPath(Util.backtrace(endNode,operations));
}
operations = this._identifySuccessors(node, operations);
}
// fail to find the path
res = {
path : [],
operations : operations
}
return res
};
/**
* Identify successors for the given node. Runs a jump point search in the
* direction of each available neighbor, adding any points found to the open
* list.
* @protected
*/
JumpPointFinderBase.prototype._identifySuccessors = function(node, operations) {
//var operations = []; // #1
// console.log("JumpPoint2");
var grid = this.grid,
heuristic = this.heuristic,
openList = this.openList,
endX = this.endNode.x,
endY = this.endNode.y,
neighbors, neighbor,
jumpPoint, i, l,
x = node.x, y = node.y,
jx, jy, dx, dy, d, ng, jumpNode,
abs = Math.abs, max = Math.max;
neighbors = this._findNeighbors(node);
for(i = 0, l = neighbors.length; i < l; ++i) {
neighbor = neighbors[i];
// console.log("a",operations)
res = this._jump(neighbor[0], neighbor[1], x, y, operations);
jumpPoint = res['jumppoint']
operations = res['operations']
// console.log("b",res)
if (jumpPoint) {
jx = jumpPoint[0];
jy = jumpPoint[1];
jumpNode = grid.getNodeAt(jx, jy);
if (jumpNode.closed) {
continue;
}
// include distance, as parent may not be immediately adjacent:
d = Heuristic.octile(abs(jx - x), abs(jy - y));
ng = node.g + d; // next `g` value
if (!jumpNode.opened || ng < jumpNode.g) {
jumpNode.g = ng;
jumpNode.h = jumpNode.h || heuristic(abs(jx - endX), abs(jy - endY));
jumpNode.f = jumpNode.g + jumpNode.h;
jumpNode.parent = node;
if (!jumpNode.opened) {
openList.push(jumpNode);
jumpNode.opened = true;
operations.push({ // #4
x: jumpNode.x,
y: jumpNode.y,
attr: 'opened',
value: true
});
} else {
openList.updateItem(jumpNode);
}
}
}
}
return operations;
};
module.exports = JumpPointFinderBase;