implement tile movement

js/game_manager.js

@@ -1,9 +1,12 @@
-function GameManager(size, actuator) {
-  this.size       = size; // Grid size
-  this.actuator   = actuator;
+function GameManager(size, InputManager, Actuator) {
+  this.size         = size; // Size of the grid
+  this.inputManager = new InputManager;
+  this.actuator     = new Actuator;
 
-  this.startTiles = 2;
-  this.grid       = new Grid(this.size);
+  this.startTiles   = 2;
+  this.grid         = new Grid(this.size);
+
+  this.inputManager.on("move", this.move.bind(this));
 
   this.setup();
 }
@@ -25,10 +28,12 @@ GameManager.prototype.addStartTiles = function () {
 
 // Adds a tile in a random position
 GameManager.prototype.addRandomTile = function () {
-  var value = Math.random() < 0.9 ? 2 : 4;
-  var tile = new Tile(this.grid.randomAvailableCell(), value);
-  
-  this.grid.insertTile(tile);
+  if (this.grid.cellsAvailable()) {
+    var value = Math.random() < 0.9 ? 2 : 4;
+    var tile = new Tile(this.grid.randomAvailableCell(), value);
+
+    this.grid.insertTile(tile);
+  }
 };
 
 // Sends the updated grid to the actuator
@@ -36,9 +41,94 @@ GameManager.prototype.actuate = function () {
   this.actuator.actuate(this.grid);
 };
 
-// Move the grid in the specified direction
+// Saves all the current tile positions
+GameManager.prototype.saveTilePositions = function () {
+  this.grid.eachCell(function (x, y, tile) {
+    if (tile) {
+      tile.savePosition();
+    }
+  });
+};
+
+// Move a tile and its representation
+GameManager.prototype.moveTile = function (tile, cell) {
+  this.grid.cells[tile.x][tile.y] = null;
+  this.grid.cells[cell.x][cell.y] = tile;
+  tile.x = cell.x;
+  tile.y = cell.y;
+};
+
+// Move tiles on the grid in the specified direction
 GameManager.prototype.move = function (direction) {
   // 0: up, 1: right, 2:down, 3: left
+  var self = this;
 
+  var cell, tile;
+
+  var vector     = this.getVector(direction);
+  var traversals = this.buildTraversals(vector);
+
+  // Save the current tile positions (for actuator awareness)
+  this.saveTilePositions();
+
+  // Traverse the grid in the right direction and move tiles
+  traversals.x.forEach(function (x) {
+    traversals.y.forEach(function (y) {
+      cell = { x: x, y: y };
+      tile = self.grid.cellContent(cell);
+
+      if (tile) {
+        var pos = self.findFarthestPosition(cell, vector);
+        console.log(pos);
+        self.moveTile(tile, pos);
+      }
+    });
+  });
+
+  this.addRandomTile();
+  console.log(16 - this.grid.availableCells().length);
   this.actuate();
 };
+
+// Get the vector representing the chosen direction
+GameManager.prototype.getVector = function (direction) {
+  // Vectors representing tile movement
+  var map = {
+    0: { x: 0,  y: -1 }, // up
+    1: { x: 1,  y: 0 },  // right
+    2: { x: 0,  y: 1 },  // down
+    3: { x: -1, y: 0 }   // left
+  };
+
+  return map[direction];
+};
+
+// Build a list of positions to traverse in the right order
+GameManager.prototype.buildTraversals = function (vector) {
+  var traversals = { x: [], y: [] };
+
+  for (var pos = 0; pos < this.size; pos++) {
+    traversals.x.push(pos);
+    traversals.y.push(pos);
+  }
+
+  // Always traverse from the farthest cell in the chosen direction
+  if (vector.x === 1) traversals.x = traversals.x.reverse();
+  if (vector.y === 1) traversals.y = traversals.y.reverse();
+
+  return traversals;
+};
+
+GameManager.prototype.findFarthestPosition = function (cell, vector) {
+  var previous;
+
+  // Progress towards the vector direction until an obstacle is found
+  do {
+    previous = cell;
+    cell     = { x: previous.x + vector.x, y: previous.y + vector.y };
+  } while (cell.x >= 0 && cell.x < this.size &&
+           cell.y >= 0 && cell.y < this.size &&
+           this.grid.cellAvailable(cell));
+
+  return previous;
+};