Newsletter addition: WeightedRandomize

Author: mikewesthad

v3/src/gameobjects/tilemap/Tilemap.js

@@ -1205,6 +1205,23 @@ var Tilemap = new Class({
         return TilemapComponents.TileToWorldXY(tileX, tileY, point, camera, layer);
     },
 
+    /**
+     * See component documentation. If no layer specified, the map's current layer is used. This
+     * cannot be applied to StaticTilemapLayers.
+     *
+     * @return {this|null} Returns this, or null if the layer given was invalid.
+     */
+    weightedRandomize: function (tileX, tileY, width, height, weightedIndexes, layer)
+    {
+        layer = this.getLayer(layer);
+        if (this._isStaticCall(layer, 'randomize')) { return this; }
+        if (layer !== null)
+        {
+            TilemapComponents.WeightedRandomize(tileX, tileY, width, height, weightedIndexes, layer);
+        }
+        return this;
+    },
+
     /**
      * See component documentation. If no layer specified, the map's current layer is used.
      *

v3/src/gameobjects/tilemap/components/WeightedRandomize.js

@@ -0,0 +1,60 @@
+var GetTilesWithin = require('./GetTilesWithin');
+
+/**
+ * Randomizes the indexes of a rectangular region of tiles (in tile coordinates) within the
+ * specified layer. Each tile will recieve a new index. New indexes are drawn from the given
+ * weightedIndexes array. An example weighted array:
+ *
+ * [
+ *  { index: 6, weight: 4 },    // Probability of index 6 is 4 / 8
+ *  { index: 7, weight: 2 },    // Probability of index 7 would be 2 / 8
+ *  { index: 8, weight: 1.5 },  // Probability of index 8 would be 1.5 / 8
+ *  { index: 26, weight: 0.5 }  // Probability of index 27 would be 0.5 / 8
+ * ]
+ *
+ * The probability of any index being choose is (the index's weight) / (sum of all weights). This
+ * method only modifies tile indexes and does not change collisioninformation.
+ *
+ * @param {integer} [tileX=0] - [description]
+ * @param {integer} [tileY=0] - [description]
+ * @param {integer} [width=max width based on tileX] - [description]
+ * @param {integer} [height=max height based on tileY] - [description]
+ * @param {object[]} [weightedIndexes] - An array of objects to randomly draw from during
+ * randomization. They should be in the form: { index: 0, weight: 4 }.
+ * @param {LayerData} layer - [description]
+ */
+var WeightedRandomize = function (tileX, tileY, width, height, weightedIndexes, layer)
+{
+    if (weightedIndexes === undefined) { return; }
+
+    var i;
+    var tiles = GetTilesWithin(tileX, tileY, width, height, null, layer);
+
+    var weightTotal = 0;
+    for (i = 0; i < weightedIndexes.length; i++)
+    {
+        weightTotal += weightedIndexes[i].weight;
+    }
+
+    if (weightTotal <= 0) { return; }
+
+    for (i = 0; i < tiles.length; i++)
+    {
+        var rand = Math.random() * weightTotal;
+        var sum = 0;
+        var randomIndex = -1;
+        for (var j = 0; j < weightedIndexes.length; j++)
+        {
+            sum += weightedIndexes[j].weight;
+            if (rand <= sum)
+            {
+                randomIndex = weightedIndexes[j].index;
+                break;
+            }
+        }
+
+        tiles[i].index = randomIndex;
+    }
+};
+
+module.exports = WeightedRandomize;

v3/src/gameobjects/tilemap/components/index.js

@@ -35,6 +35,7 @@ module.exports = {
     TileToWorldX: require('./TileToWorldX'),
     TileToWorldXY: require('./TileToWorldXY'),
     TileToWorldY: require('./TileToWorldY'),
+    WeightedRandomize: require('./WeightedRandomize'),
     WorldToTileX: require('./WorldToTileX'),
     WorldToTileXY: require('./WorldToTileXY'),
     WorldToTileY: require('./WorldToTileY')

v3/src/gameobjects/tilemap/dynamiclayer/DynamicTilemapLayer.js

@@ -463,6 +463,17 @@ var DynamicTilemapLayer = new Class({
         return TilemapComponents.TileToWorldXY(tileX, tileY, point, camera, this.layer);
     },
 
+    /**
+     * See component documentation.
+     *
+     * @return {this}
+     */
+    weightedRandomize: function (tileX, tileY, width, height, weightedIndexes)
+    {
+        TilemapComponents.WeightedRandomize(tileX, tileY, width, height, weightedIndexes, this.layer);
+        return this;
+    },
+
     /**
      * See component documentation.
      *