Add custom condition

README.md

@@ -68,6 +68,11 @@ easystar.enableSync();
 ```javascript
 easystar.setDirectionalCondition(x, y, [EasyStar.TOP, EasyStar.BOTTOM]); // only accessible from the top and left
 ```
+```javascript
+easystar.setCustomCondition(x, y, function(sourceNode, thisNode, grid) {
+    return grid[sourceNode.y][sourceNode.x] === 2 // only allow '2' nodes to access the node a [x, y]
+}) 
+```
 
 ## Usage
 

index.d.ts

@@ -8,9 +8,9 @@ export const LEFT: 'LEFT'
 export const TOP_LEFT: 'TOP_LEFT'
 
 type Direction = 'TOP' | 'TOP_RIGHT' | 'RIGHT' | 'BOTTOM_RIGHT' | 'BOTTOM' | 'BOTTOM_LEFT' | 'LEFT' | 'TOP_LEFT'
+type CustomCheck = (source?: { x: number, y: number }, thisNode?: { x: number, y: number}, grid?: number[][]) => boolean
 
 export class js {
-
   /**
    * Sets the collision grid that EasyStar uses.
    *
@@ -158,4 +158,26 @@ export class js {
    * Remove all directional conditions
    */
   removeAllDirectionalConditions(): void
+
+  /**
+   * Sets a custom condition on a tile
+   *
+   * @param {Number} x The x value of the point.
+   * @param {Number} y The y value of the point.
+   * @param {Function} customCheck Function to check whether a movement onto a tile is valid
+   */
+  setCustomCondition(x: number, y: number, customCheck: CustomCheck): void
+
+  /**
+   * Remove all custom conditions
+   */
+  removeAllCustomConditions(): void
 }
+
+/**
+ * Calculate the direction to a node
+ *
+ * @param {Object} sourceNode The source node
+ * @param {Object} destinationNode The destination node
+ */
+export function calculateDirection(sourceNode: { x: number, y: number }, destinationNode: { x: number, y: number }): Direction

src/easystar.js

@@ -25,6 +25,7 @@ EasyStar.js = function() {
     var costMap = {};
     var pointsToCost = {};
     var directionalConditions = {};
+    var customConditions = {};
     var allowCornerCutting = true;
     var iterationsSoFar;
     var instances = [];
@@ -155,6 +156,25 @@ EasyStar.js = function() {
         directionalConditions = {};
     };
 
+    /**
+    * Sets a custom condition on a tile
+    *
+    * @param {Number} x The x value of the point.
+    * @param {Number} y The y value of the point.
+    * @param {Function} customCheck Function that takes the sourceNode and the grid as an argument
+    * and returns a boolean.
+    **/
+    this.setCustomCondition = function(x, y, customCheck) {
+        customConditions[x + '_' + y] = customCheck;
+    };
+
+    /**
+    * Remove all custom conditions
+    **/
+    this.removeAllCustomConditions = function () {
+        customConditions = {}
+    };
+
     /**
     * Sets the number of search iterations per calculation.
     * A lower number provides a slower result, but more practical if you
@@ -443,7 +463,7 @@ EasyStar.js = function() {
     // Helpers
     var isTileWalkable = function(collisionGrid, acceptableTiles, x, y, sourceNode) {
         if (directionalConditions[x + "_" + y]) {
-            var direction = calculateDirection(sourceNode.x - x, sourceNode.y - y)
+            var direction = EasyStar.calculateDirection(sourceNode, { x: x, y: y })
             var directionIncluded = function () {
                 for (var i = 0; i < directionalConditions[x + "_" + y].length; i++) {
                     if (directionalConditions[x + "_" + y][i] === direction) return true
@@ -452,6 +472,12 @@ EasyStar.js = function() {
             }
             if (!directionIncluded()) return false
         }
+
+        if (customConditions[x + "_" + y] &&
+            !customConditions[x + "_" + y](sourceNode, { x: x, y: y}, collisionGrid)) {
+            return false
+        }
+
         for (var i = 0; i < acceptableTiles.length; i++) {
             if (collisionGrid[y][x] === acceptableTiles[i]) {
                 return true;
@@ -461,23 +487,6 @@ EasyStar.js = function() {
         return false;
     };
 
-    /**
-     * -1, -1 | 0, -1  | 1, -1
-     * -1,  0 | SOURCE | 1,  0
-     * -1,  1 | 0,  1  | 1,  1
-     */
-    var calculateDirection = function (diffX, diffY) {
-        if (diffX === 0, diffY === -1) return EasyStar.BOTTOM
-        else if (diffX === 1, diffY === -1) return EasyStar.BOTTOM_LEFT
-        else if (diffX === 1, diffY === 0) return EasyStar.LEFT
-        else if (diffX === 1, diffY === 1) return EasyStar.TOP_LEFT
-        else if (diffX === 0, diffY === 1) return EasyStar.TOP
-        else if (diffX === -1, diffY === 1) return EasyStar.TOP_RIGHT
-        else if (diffX === -1, diffY === 0) return EasyStar.RIGHT
-        else if (diffX === -1, diffY === -1) return EasyStar.BOTTOM_RIGHT
-        throw new Error('These differences are not valid: ' + diffX + ', ' + diffY)
-    };
-
     var getTileCost = function(x, y) {
         return pointsToCost[x + '_' + y] || costMap[collisionGrid[y][x]]
     };
@@ -516,6 +525,26 @@ EasyStar.js = function() {
     };
 }
 
+
+/**
+ * -1, -1 | 0, -1  | 1, -1
+ * -1,  0 | SOURCE | 1,  0
+ * -1,  1 | 0,  1  | 1,  1
+ */
+EasyStar.calculateDirection = function (sourceNode, destinationNode) {
+    var diffX = sourceNode.x - destinationNode.x
+    var diffY = sourceNode.y - destinationNode.y
+    if (diffX === 0, diffY === -1) return EasyStar.BOTTOM
+    else if (diffX === 1, diffY === -1) return EasyStar.BOTTOM_LEFT
+    else if (diffX === 1, diffY === 0) return EasyStar.LEFT
+    else if (diffX === 1, diffY === 1) return EasyStar.TOP_LEFT
+    else if (diffX === 0, diffY === 1) return EasyStar.TOP
+    else if (diffX === -1, diffY === 1) return EasyStar.TOP_RIGHT
+    else if (diffX === -1, diffY === 0) return EasyStar.RIGHT
+    else if (diffX === -1, diffY === -1) return EasyStar.BOTTOM_RIGHT
+    throw new Error('These differences are not valid: ' + diffX + ', ' + diffY)
+};
+
 EasyStar.TOP = 'TOP'
 EasyStar.TOP_RIGHT = 'TOP_RIGHT'
 EasyStar.RIGHT = 'RIGHT'

test/easystartest.js

@@ -266,6 +266,31 @@ describe("EasyStar.js", function() {
           done();
       });
 
+      easyStar.calculate();
+  })
+  it("It should handle tiles with a custom condition", function (done) {
+      var easyStar = new EasyStar.js();
+      var grid = [
+          [0, 1, 0],
+          [0, 0, 4],
+          [4, 0, 0],
+      ];
+      easyStar.setGrid(grid);
+      easyStar.setAcceptableTiles([0, 4, 5]);
+      easyStar.setCustomCondition(1, 1, function(source, thisNode, grid) {
+          return grid[source.y][source.x] === 4
+      })
+      easyStar.setCustomCondition(1, 2, function (source, thisNode, grid) {
+          return EasyStar.calculateDirection(source, thisNode) === 'LEFT' && grid[source.y][source.x] === 4
+      })
+
+      easyStar.findPath(0, 0, 2, 0, function (path) {
+          expect(path).not.toBeNull();
+          expect(path[3]).toEqual({ x: 1, y: 2 })
+          expect(path.length).toEqual(7);
+          done();
+      });
+
       easyStar.calculate();
   })
 });