// The MIT License (MIT)
// Copyright (c) 2012-2015 Bryce Neal
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
// Adapted for High Fidelity by James B. Pollack on 11/6/2015
loadEasyStar = function() {
var ezStar = eStar();
return new ezStar.js()
}
var eStar = function() {
var EasyStar = EasyStar || {};
/**
* A simple Node that represents a single tile on the grid.
* @param {Object} parent The parent node.
* @param {Number} x The x position on the grid.
* @param {Number} y The y position on the grid.
* @param {Number} costSoFar How far this node is in moves*cost from the start.
* @param {Number} simpleDistanceToTarget Manhatten distance to the end point.
**/
EasyStar.Node = function(parent, x, y, costSoFar, simpleDistanceToTarget) {
this.parent = parent;
this.x = x;
this.y = y;
this.costSoFar = costSoFar;
this.simpleDistanceToTarget = simpleDistanceToTarget;
/**
* @return {Number} Best guess distance of a cost using this node.
**/
this.bestGuessDistance = function() {
return this.costSoFar + this.simpleDistanceToTarget;
}
};
// Constants
EasyStar.Node.OPEN_LIST = 0;
EasyStar.Node.CLOSED_LIST = 1;
/**
* This is an improved Priority Queue data type implementation that can be used to sort any object type.
* It uses a technique called a binary heap.
*
* For more on binary heaps see: http://en.wikipedia.org/wiki/Binary_heap
*
* @param {String} criteria The criteria by which to sort the objects.
* This should be a property of the objects you're sorting.
*
* @param {Number} heapType either PriorityQueue.MAX_HEAP or PriorityQueue.MIN_HEAP.
**/
EasyStar.PriorityQueue = function(criteria, heapType) {
this.length = 0; //The current length of heap.
var queue = [];
var isMax = false;
//Constructor
if (heapType == EasyStar.PriorityQueue.MAX_HEAP) {
isMax = true;
} else if (heapType == EasyStar.PriorityQueue.MIN_HEAP) {
isMax = false;
} else {
throw heapType + " not supported.";
}
/**
* Inserts the value into the heap and sorts it.
*
* @param value The object to insert into the heap.
**/
this.insert = function(value) {
if (!value.hasOwnProperty(criteria)) {
throw "Cannot insert " + value + " because it does not have a property by the name of " + criteria + ".";
}
queue.push(value);
this.length++;
bubbleUp(this.length - 1);
}
/**
* Peeks at the highest priority element.
*
* @return the highest priority element
**/
this.getHighestPriorityElement = function() {
return queue[0];
}
/**
* Removes and returns the highest priority element from the queue.
*
* @return the highest priority element
**/
this.shiftHighestPriorityElement = function() {
if (this.length === 0) {
throw ("There are no more elements in your priority queue.");
} else if (this.length === 1) {
var onlyValue = queue[0];
queue = [];
this.length = 0;
return onlyValue;
}
var oldRoot = queue[0];
var newRoot = queue.pop();
this.length--;
queue[0] = newRoot;
swapUntilQueueIsCorrect(0);
return oldRoot;
}
var bubbleUp = function(index) {
if (index === 0) {
return;
}
var parent = getParentOf(index);
if (evaluate(index, parent)) {
swap(index, parent);
bubbleUp(parent);
} else {
return;
}
}
var swapUntilQueueIsCorrect = function(value) {
var left = getLeftOf(value);
var right = getRightOf(value);
if (evaluate(left, value)) {
swap(value, left);
swapUntilQueueIsCorrect(left);
} else if (evaluate(right, value)) {
swap(value, right);
swapUntilQueueIsCorrect(right);
} else if (value == 0) {
return;
} else {
swapUntilQueueIsCorrect(0);
}
}
var swap = function(self, target) {
var placeHolder = queue[self];
queue[self] = queue[target];
queue[target] = placeHolder;
}
var evaluate = function(self, target) {
if (queue[target] === undefined || queue[self] === undefined) {
return false;
}
var selfValue;
var targetValue;
// Check if the criteria should be the result of a function call.
if (typeof queue[self][criteria] === 'function') {
selfValue = queue[self][criteria]();
targetValue = queue[target][criteria]();
} else {
selfValue = queue[self][criteria];
targetValue = queue[target][criteria];
}
if (isMax) {
if (selfValue > targetValue) {
return true;
} else {
return false;
}
} else {
if (selfValue < targetValue) {
return true;
} else {
return false;
}
}
}
var getParentOf = function(index) {
return Math.floor((index - 1) / 2);
}
var getLeftOf = function(index) {
return index * 2 + 1;
}
var getRightOf = function(index) {
return index * 2 + 2;
}
};
// Constants
EasyStar.PriorityQueue.MAX_HEAP = 0;
EasyStar.PriorityQueue.MIN_HEAP = 1;
/**
* Represents a single instance of EasyStar.
* A path that is in the queue to eventually be found.
*/
EasyStar.instance = function() {
this.isDoneCalculating = true;
this.pointsToAvoid = {};
this.startX;
this.callback;
this.startY;
this.endX;
this.endY;
this.nodeHash = {};
this.openList;
};
/**
* EasyStar.js
* github.com/prettymuchbryce/EasyStarJS
* Licensed under the MIT license.
*
* Implementation By Bryce Neal (@prettymuchbryce)
**/
EasyStar.js = function() {
var STRAIGHT_COST = 1.0;
var DIAGONAL_COST = 1.4;
var syncEnabled = false;
var pointsToAvoid = {};
var collisionGrid;
var costMap = {};
var pointsToCost = {};
var allowCornerCutting = true;
var iterationsSoFar;
var instances = [];
var iterationsPerCalculation = Number.MAX_VALUE;
var acceptableTiles;
var diagonalsEnabled = false;
/**
* Sets the collision grid that EasyStar uses.
*
* @param {Array|Number} tiles An array of numbers that represent
* which tiles in your grid should be considered
* acceptable, or "walkable".
**/
this.setAcceptableTiles = function(tiles) {
if (tiles instanceof Array) {
// Array
acceptableTiles = tiles;
} else if (!isNaN(parseFloat(tiles)) && isFinite(tiles)) {
// Number
acceptableTiles = [tiles];
}
};
/**
* Enables sync mode for this EasyStar instance..
* if you're into that sort of thing.
**/
this.enableSync = function() {
syncEnabled = true;
};
/**
* Disables sync mode for this EasyStar instance.
**/
this.disableSync = function() {
syncEnabled = false;
};
/**
* Enable diagonal pathfinding.
*/
this.enableDiagonals = function() {
diagonalsEnabled = true;
}
/**
* Disable diagonal pathfinding.
*/
this.disableDiagonals = function() {
diagonalsEnabled = false;
}
/**
* Sets the collision grid that EasyStar uses.
*
* @param {Array} grid The collision grid that this EasyStar instance will read from.
* This should be a 2D Array of Numbers.
**/
this.setGrid = function(grid) {
collisionGrid = grid;
//Setup cost map
for (var y = 0; y < collisionGrid.length; y++) {
for (var x = 0; x < collisionGrid[0].length; x++) {
if (!costMap[collisionGrid[y][x]]) {
costMap[collisionGrid[y][x]] = 1
}
}
}
};
/**
* Sets the tile cost for a particular tile type.
*
* @param {Number} The tile type to set the cost for.
* @param {Number} The multiplicative cost associated with the given tile.
**/
this.setTileCost = function(tileType, cost) {
costMap[tileType] = cost;
};
/**
* Sets the an additional cost for a particular point.
* Overrides the cost from setTileCost.
*
* @param {Number} x The x value of the point to cost.
* @param {Number} y The y value of the point to cost.
* @param {Number} The multiplicative cost associated with the given point.
**/
this.setAdditionalPointCost = function(x, y, cost) {
pointsToCost[x + '_' + y] = cost;
};
/**
* Remove the additional cost for a particular point.
*
* @param {Number} x The x value of the point to stop costing.
* @param {Number} y The y value of the point to stop costing.
**/
this.removeAdditionalPointCost = function(x, y) {
delete pointsToCost[x + '_' + y];
}
/**
* Remove all additional point costs.
**/
this.removeAllAdditionalPointCosts = function() {
pointsToCost = {};
}
/**
* Sets the number of search iterations per calculation.
* A lower number provides a slower result, but more practical if you
* have a large tile-map and don't want to block your thread while
* finding a path.
*
* @param {Number} iterations The number of searches to prefrom per calculate() call.
**/
this.setIterationsPerCalculation = function(iterations) {
iterationsPerCalculation = iterations;
};
/**
* Avoid a particular point on the grid,
* regardless of whether or not it is an acceptable tile.
*
* @param {Number} x The x value of the point to avoid.
* @param {Number} y The y value of the point to avoid.
**/
this.avoidAdditionalPoint = function(x, y) {
pointsToAvoid[x + "_" + y] = 1;
};
/**
* Stop avoiding a particular point on the grid.
*
* @param {Number} x The x value of the point to stop avoiding.
* @param {Number} y The y value of the point to stop avoiding.
**/
this.stopAvoidingAdditionalPoint = function(x, y) {
delete pointsToAvoid[x + "_" + y];
};
/**
* Enables corner cutting in diagonal movement.
**/
this.enableCornerCutting = function() {
allowCornerCutting = true;
};
/**
* Disables corner cutting in diagonal movement.
**/
this.disableCornerCutting = function() {
allowCornerCutting = false;
};
/**
* Stop avoiding all additional points on the grid.
**/
this.stopAvoidingAllAdditionalPoints = function() {
pointsToAvoid = {};
};
/**
* Find a path.
*
* @param {Number} startX The X position of the starting point.
* @param {Number} startY The Y position of the starting point.
* @param {Number} endX The X position of the ending point.
* @param {Number} endY The Y position of the ending point.
* @param {Function} callback A function that is called when your path
* is found, or no path is found.
*
**/
this.findPath = function(startX, startY, endX, endY, callback) {
// Wraps the callback for sync vs async logic
var callbackWrapper = function(result) {
if (syncEnabled) {
callback(result);
} else {
Script.setTimeout(function() {
callback(result);
}, 1);
}
}
// No acceptable tiles were set
if (acceptableTiles === undefined) {
throw new Error("You can't set a path without first calling setAcceptableTiles() on EasyStar.");
}
// No grid was set
if (collisionGrid === undefined) {
throw new Error("You can't set a path without first calling setGrid() on EasyStar.");
}
// Start or endpoint outside of scope.
if (startX < 0 || startY < 0 || endX < 0 || endX < 0 ||
startX > collisionGrid[0].length - 1 || startY > collisionGrid.length - 1 ||
endX > collisionGrid[0].length - 1 || endY > collisionGrid.length - 1) {
throw new Error("Your start or end point is outside the scope of your grid.");
}
// Start and end are the same tile.
if (startX === endX && startY === endY) {
callbackWrapper([]);
return;
}
// End point is not an acceptable tile.
var endTile = collisionGrid[endY][endX];
var isAcceptable = false;
for (var i = 0; i < acceptableTiles.length; i++) {
if (endTile === acceptableTiles[i]) {
isAcceptable = true;
break;
}
}
if (isAcceptable === false) {
callbackWrapper(null);
return;
}
// Create the instance
var instance = new EasyStar.instance();
instance.openList = new EasyStar.PriorityQueue("bestGuessDistance", EasyStar.PriorityQueue.MIN_HEAP);
instance.isDoneCalculating = false;
instance.nodeHash = {};
instance.startX = startX;
instance.startY = startY;
instance.endX = endX;
instance.endY = endY;
instance.callback = callbackWrapper;
instance.openList.insert(coordinateToNode(instance, instance.startX,
instance.startY, null, STRAIGHT_COST));
instances.push(instance);
};
/**
* This method steps through the A* Algorithm in an attempt to
* find your path(s). It will search 4-8 tiles (depending on diagonals) for every calculation.
* You can change the number of calculations done in a call by using
* easystar.setIteratonsPerCalculation().
**/
this.calculate = function() {
if (instances.length === 0 || collisionGrid === undefined || acceptableTiles === undefined) {
return;
}
for (iterationsSoFar = 0; iterationsSoFar < iterationsPerCalculation; iterationsSoFar++) {
if (instances.length === 0) {
return;
}
if (syncEnabled) {
// If this is a sync instance, we want to make sure that it calculates synchronously.
iterationsSoFar = 0;
}
// Couldn't find a path.
if (instances[0].openList.length === 0) {
var ic = instances[0];
ic.callback(null);
instances.shift();
continue;
}
var searchNode = instances[0].openList.shiftHighestPriorityElement();
var tilesToSearch = [];
searchNode.list = EasyStar.Node.CLOSED_LIST;
if (searchNode.y > 0) {
tilesToSearch.push({
instance: instances[0],
searchNode: searchNode,
x: 0,
y: -1,
cost: STRAIGHT_COST * getTileCost(searchNode.x, searchNode.y - 1)
});
}
if (searchNode.x < collisionGrid[0].length - 1) {
tilesToSearch.push({
instance: instances[0],
searchNode: searchNode,
x: 1,
y: 0,
cost: STRAIGHT_COST * getTileCost(searchNode.x + 1, searchNode.y)
});
}
if (searchNode.y < collisionGrid.length - 1) {
tilesToSearch.push({
instance: instances[0],
searchNode: searchNode,
x: 0,
y: 1,
cost: STRAIGHT_COST * getTileCost(searchNode.x, searchNode.y + 1)
});
}
if (searchNode.x > 0) {
tilesToSearch.push({
instance: instances[0],
searchNode: searchNode,
x: -1,
y: 0,
cost: STRAIGHT_COST * getTileCost(searchNode.x - 1, searchNode.y)
});
}
if (diagonalsEnabled) {
if (searchNode.x > 0 && searchNode.y > 0) {
if (allowCornerCutting ||
(isTileWalkable(collisionGrid, acceptableTiles, searchNode.x, searchNode.y - 1) &&
isTileWalkable(collisionGrid, acceptableTiles, searchNode.x - 1, searchNode.y))) {
tilesToSearch.push({
instance: instances[0],
searchNode: searchNode,
x: -1,
y: -1,
cost: DIAGONAL_COST * getTileCost(searchNode.x - 1, searchNode.y - 1)
});
}
}
if (searchNode.x < collisionGrid[0].length - 1 && searchNode.y < collisionGrid.length - 1) {
if (allowCornerCutting ||
(isTileWalkable(collisionGrid, acceptableTiles, searchNode.x, searchNode.y + 1) &&
isTileWalkable(collisionGrid, acceptableTiles, searchNode.x + 1, searchNode.y))) {
tilesToSearch.push({
instance: instances[0],
searchNode: searchNode,
x: 1,
y: 1,
cost: DIAGONAL_COST * getTileCost(searchNode.x + 1, searchNode.y + 1)
});
}
}
if (searchNode.x < collisionGrid[0].length - 1 && searchNode.y > 0) {
if (allowCornerCutting ||
(isTileWalkable(collisionGrid, acceptableTiles, searchNode.x, searchNode.y - 1) &&
isTileWalkable(collisionGrid, acceptableTiles, searchNode.x + 1, searchNode.y))) {
tilesToSearch.push({
instance: instances[0],
searchNode: searchNode,
x: 1,
y: -1,
cost: DIAGONAL_COST * getTileCost(searchNode.x + 1, searchNode.y - 1)
});
}
}
if (searchNode.x > 0 && searchNode.y < collisionGrid.length - 1) {
if (allowCornerCutting ||
(isTileWalkable(collisionGrid, acceptableTiles, searchNode.x, searchNode.y + 1) &&
isTileWalkable(collisionGrid, acceptableTiles, searchNode.x - 1, searchNode.y))) {
tilesToSearch.push({
instance: instances[0],
searchNode: searchNode,
x: -1,
y: 1,
cost: DIAGONAL_COST * getTileCost(searchNode.x - 1, searchNode.y + 1)
});
}
}
}
// First sort all of the potential nodes we could search by their cost + heuristic distance.
tilesToSearch.sort(function(a, b) {
var aCost = a.cost + getDistance(searchNode.x + a.x, searchNode.y + a.y, instances[0].endX, instances[0].endY)
var bCost = b.cost + getDistance(searchNode.x + b.x, searchNode.y + b.y, instances[0].endX, instances[0].endY)
if (aCost < bCost) {
return -1;
} else if (aCost === bCost) {
return 0;
} else {
return 1;
}
});
var isDoneCalculating = false;
// Search all of the surrounding nodes
for (var i = 0; i < tilesToSearch.length; i++) {
checkAdjacentNode(tilesToSearch[i].instance, tilesToSearch[i].searchNode,
tilesToSearch[i].x, tilesToSearch[i].y, tilesToSearch[i].cost);
if (tilesToSearch[i].instance.isDoneCalculating === true) {
isDoneCalculating = true;
break;
}
}
if (isDoneCalculating) {
instances.shift();
continue;
}
}
};
// Private methods follow
var checkAdjacentNode = function(instance, searchNode, x, y, cost) {
var adjacentCoordinateX = searchNode.x + x;
var adjacentCoordinateY = searchNode.y + y;
if (pointsToAvoid[adjacentCoordinateX + "_" + adjacentCoordinateY] === undefined) {
// Handles the case where we have found the destination
if (instance.endX === adjacentCoordinateX && instance.endY === adjacentCoordinateY) {
instance.isDoneCalculating = true;
var path = [];
var pathLen = 0;
path[pathLen] = {
x: adjacentCoordinateX,
y: adjacentCoordinateY
};
pathLen++;
path[pathLen] = {
x: searchNode.x,
y: searchNode.y
};
pathLen++;
var parent = searchNode.parent;
while (parent != null) {
path[pathLen] = {
x: parent.x,
y: parent.y
};
pathLen++;
parent = parent.parent;
}
path.reverse();
var ic = instance;
var ip = path;
ic.callback(ip);
return
}
if (isTileWalkable(collisionGrid, acceptableTiles, adjacentCoordinateX, adjacentCoordinateY)) {
var node = coordinateToNode(instance, adjacentCoordinateX,
adjacentCoordinateY, searchNode, cost);
if (node.list === undefined) {
node.list = EasyStar.Node.OPEN_LIST;
instance.openList.insert(node);
} else if (node.list === EasyStar.Node.OPEN_LIST) {
if (searchNode.costSoFar + cost < node.costSoFar) {
node.costSoFar = searchNode.costSoFar + cost;
node.parent = searchNode;
}
}
}
}
};
// Helpers
var isTileWalkable = function(collisionGrid, acceptableTiles, x, y) {
for (var i = 0; i < acceptableTiles.length; i++) {
if (collisionGrid[y][x] === acceptableTiles[i]) {
return true;
}
}
return false;
};
var getTileCost = function(x, y) {
return pointsToCost[x + '_' + y] || costMap[collisionGrid[y][x]]
};
var coordinateToNode = function(instance, x, y, parent, cost) {
if (instance.nodeHash[x + "_" + y] !== undefined) {
return instance.nodeHash[x + "_" + y];
}
var simpleDistanceToTarget = getDistance(x, y, instance.endX, instance.endY);
if (parent !== null) {
var costSoFar = parent.costSoFar + cost;
} else {
costSoFar = simpleDistanceToTarget;
}
var node = new EasyStar.Node(parent, x, y, costSoFar, simpleDistanceToTarget);
instance.nodeHash[x + "_" + y] = node;
return node;
};
var getDistance = function(x1, y1, x2, y2) {
return Math.sqrt((x2 -= x1) * x2 + (y2 -= y1) * y2);
};
}
return EasyStar
}