Player movement restricted to map boundaries

This is an initial working concept; refactoring is certainly needed (in
particular, note the MapStae.movePlayer() 'bounds' argument).

index.html

@@ -130,6 +130,7 @@
     <script src="lib/MapSet.js"></script>
     <script src="lib/Map.js"></script>
     <script src="lib/MapState.js"></script>
+    <script src="lib/MapBounds.js"></script>
     <script src="lib/GameObjectFactory.js"></script>
     <script src="lib/ClassicGameObjectFactory.js"></script>
     <script src="lib/ClassicMap.js"></script>

lib/ClassicGame.js

@@ -115,9 +115,9 @@ ltjs.ClassicGame = Class( 'ClassicGame' )
             this._render.clearCanvas();
         }
 
-        var map = this._mapSet.getMapByNumber( 1 );
+        var map       = this._mapSet.getMapByNumber( 1 ),
-
+            map_state = ltjs.MapState( map, this._gameObjFactory ),
-        var map_state = ltjs.MapState( map, this._gameObjFactory );
+            bounds    = ltjs.MapBounds( map );
 
         // render the first map (hardcoded for now)
         this._render = ltjs.MapRender( ctx, this._tileSet )
@@ -141,7 +141,7 @@ ltjs.ClassicGame = Class( 'ClassicGame' )
                     return;
             }
 
-            map_state.movePlayer( dir );
+            map_state.movePlayer( dir, bounds );
         };
 
         return this;

lib/MapAction.js

@@ -29,15 +29,25 @@ ltjs.MapAction = Class( 'MapAction',
 
 
     'private _dir': 0,
+    'private _srcPos': 0,
+    'public srcPos': 0,
+
+    'private _bounds': null,
 
     'private _stateCallback': null,
     'private _moveCallback':  null,
 
 
-    __construct: function( state_callback, move_callback )
+    __construct: function( bounds, state_callback, move_callback )
     {
+        if ( !( Class.isA( ltjs.MapBounds, bounds ) ) )
+        {
+            throw TypeError( 'Invalid MapBounds provided' );
+        }
+
         this._dir = this.__self.$( 'D_UP' );
 
+        this._bounds        = bounds;
         this._stateCallback = state_callback;
         this._moveCallback  = move_callback;
     },
@@ -51,7 +61,16 @@ ltjs.MapAction = Class( 'MapAction',
 
     'public move': function()
     {
-        this._moveCallback( this._dir );
+        var method = [
+            'getLeftPos',
+            'getUpperPos',
+            'getRightPos',
+            'getLowerPos',
+        ][ this._dir ];
+
+        this._moveCallback(
+            this._bounds[ method ].call( this._bounds, this.srcPos )
+        );
     },
 
 

lib/MapBounds.js

@@ -0,0 +1,190 @@
+/**
+ * Handles map boundaries for collision detection and movement
+ *
+ *  Copyright (C) 2012  Mike Gerwitz
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+/**
+ * Calculates map bounding box
+ *
+ * This simply encapsulates the process of determining whether a given position
+ * is against an edge of the map.
+ */
+ltjs.MapBounds = Class( 'MapBounds',
+{
+    /**
+     * Map width (number of tiles)
+     * @type {number}
+     */
+    'private _mw': 0,
+
+    /**
+     * Map height (number of tiles)
+     * @type {number}
+     */
+    'private _mh': 0,
+
+
+    /**
+     * Initialize bounding box for a given map
+     *
+     * @param  {Map}  map  map for which bounds should be calculated
+     */
+    __construct: function( map )
+    {
+        if ( !( Class.isA( ltjs.Map, map ) ) )
+        {
+            throw TypeError( 'Invalid Map provided' );
+        }
+
+        // we are only interested in the dimensions of the map
+        var dimen = map.getDimensions();
+        this._mw = dimen[ 0 ];
+        this._mh = dimen[ 1 ];
+    },
+
+
+    /**
+     * Retrieve the tile position above the given position
+     *
+     * If the given tile position is at the top of the map, then the given
+     * position will be returned.
+     *
+     * @param  {number}  pos  original tile position
+     *
+     * @return  {number}  tile position above given position or current position
+     */
+    'public getUpperPos': function( pos )
+    {
+        return ( this.isAtTop( pos ) )
+            ? pos
+            : pos - 1;
+    },
+
+
+    /**
+     * Retrieve the tile position below the given position
+     *
+     * If the given tile position is at the bottom of the map, then the given
+     * position will be returned.
+     *
+     * @param  {number}  pos  original tile position
+     *
+     * @return  {number}  tile position below given position or current position
+     */
+    'public getLowerPos': function( pos )
+    {
+        return ( this.isAtBottom( pos ) )
+            ? pos
+            : pos + 1;
+    },
+
+
+    /**
+     * Retrieve the tile position to the left of the given position
+     *
+     * If the given tile position is at the leftmost column of the map, then the
+     * given position will be returned.
+     *
+     * @param  {number}  pos  original tile position
+     *
+     * @return  {number}  tile position left of given position or current
+     *                    position
+     */
+    'public getLeftPos': function( pos )
+    {
+        return ( this.isAtLeft( pos ) )
+            ? pos
+            : pos - this._mh;
+    },
+
+
+    /**
+     * Retrieve the tile position to the right of the given position
+     *
+     * If the given tile position is at the rightmost column of the map, then
+     * the given position will be returned.
+     *
+     * @param  {number}  pos  original tile position
+     *
+     * @return  {number}  tile position right of given position or current
+     *                    position
+     */
+    'public getRightPos': function( pos )
+    {
+        return ( this.isAtRight( pos ) )
+            ? pos
+            : pos + this._mh;
+    },
+
+
+    /**
+     * Determines if the given position is in the topmost row of the map
+     *
+     * @param  {number}  pos  tile position
+     *
+     * @return  {boolean}  true if within topmost row, otherwise false
+     */
+    'public isAtTop': function( pos )
+    {
+        // since tile positions are zero-indexed, we know that we're at the top
+        // if the map height divides the position
+        return ( pos % this._mh === 0 );
+    },
+
+
+    /**
+     * Determines if the given position is in the bottom row of the map
+     *
+     * @param  {number}  pos  tile position
+     *
+     * @return  {boolean}  true if within bottom row, otherwise false
+     */
+    'public isAtBottom': function( pos )
+    {
+        // this "works" because tile positions are vertically indexed
+        return this.isAtTop( pos + 1 );
+    },
+
+
+    /**
+     * Determines if the given position is in the leftmost column of the map
+     *
+     * @param  {number}  pos  tile position
+     *
+     * @return  {boolean}  true if within leftmost column, otherwise false
+     */
+    'public isAtLeft': function( pos )
+    {
+        // check if index is within the left-most column
+        return ( pos <= this._mh );
+    },
+
+
+    /**
+     * Determines if the given position is in the rightmost column of the map
+     *
+     * @param  {number}  pos  tile position
+     *
+     * @return  {boolean}  true if within rightmost column, otherwise false
+     */
+    'public isAtRight': function( pos )
+    {
+        // check if index is within the right-most column
+        return ( pos >= ( this._mh * ( this._mw - 1 ) ) );
+    },
+} );

lib/MapState.js

@@ -437,13 +437,6 @@ ltjs.MapState = Class( 'MapState',
     },
 
 
-    // TODO
-    'private _calcPos': function( pos, dir )
-    {
-        return pos - 1;
-    },
-
-
     /**
      * Creates a callback to alter the state of an object
      *
@@ -497,15 +490,14 @@ ltjs.MapState = Class( 'MapState',
     {
         var _self = this;
 
-        return function( dir )
+        return function( dest )
         {
-            var newpos = _self._calcPos( pos, dir );
+            _self._moveObj( obj, pos, dest );
-            _self._moveObj( obj, pos, newpos );
 
             // call continuation with new position, if requested
             if ( typeof c === 'function' )
             {
-                c( newpos );
+                c( dest );
             }
         };
     },
@@ -517,17 +509,21 @@ ltjs.MapState = Class( 'MapState',
      * The directions, as defined in MapAction, are: 0:left, 1:up, 2:right,
      * 3:down.
      *
+     * XXX: the bounds argument is temporary
+     *
      * @param  {number}     direction  direction code
+     * @param  {MapBounds}  bounds     map boundaries
      *
      * @return  {undefined}
      */
-    'public movePlayer': function( direction )
+    'public movePlayer': function( direction, bounds )
     {
         var _self  = this,
             player = this._player;
 
         // XXX: tightly coupled
         var action = ltjs.MapAction(
+            bounds,
             this._createStateCallback( player, this._playerPos, function( o )
             {
                 _self._player = o;
@@ -540,6 +536,7 @@ ltjs.MapState = Class( 'MapState',
         );
 
         action.direction = direction;
+        action.srcPos    = this._playerPos;
         player.move( action );
     }
 } );