Wolfenstein 3D browser version

This is the code for the browser version of Wolfenstein 3D which is
playable on http://www.wolfenstein.com/game_NA.php

js/pushwall.js

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+/*
+* ===========================================================================
+* 
+* Wolf3D Browser Version GPL Source Code
+* Copyright (C) 2012 id Software LLC, a ZeniMax Media company. 
+* 
+* This file is part of the Wolf3D Browser Version GPL Source Code ("Wolf3D Browser Source Code").  
+* 
+* Wolf3D Browser Source Code is free software: you can redistribute it and/or modify
+* it under the terms of the GNU General Public License as published by
+* the Free Software Foundation, either version 2 of the License, or
+* (at your option) any later version.
+* 
+* Wolf3D Browser Source Code 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 General Public License for more details.
+* 
+* You should have received a copy of the GNU General Public License version 2
+* along with Wolf3D Browser Source Code.  If not, see <http://www.gnu.org/licenses/>.
+* 
+* If you have questions concerning this license, you may contact in writing id Software LLC, c/o ZeniMax Media Inc., Suite 120, Rockville, Maryland 20850 USA.
+* 
+* ===========================================================================
+*/
+
+/** 
+ * @namespace 
+ * @description Push wall management
+ */
+Wolf.PushWall = (function() {
+
+    var PWall = {};
+    reset();
+
+    function reset() {
+        PWall.active = false;
+        PWall.tilesMoved = 0;
+        PWall.pointsMoved = 0;
+        PWall.dir = 0;
+        PWall.x = 0;
+        PWall.y = 0;
+        PWall.dx = 0; 
+        PWall.dy = 0;
+        PWall.texX = 0;
+        PWall.texY = 0;
+    }
+
+    
+    function push(level, x, y, dir) {
+        var dx, dy;
+
+        if (PWall.active) {
+            return false; // another PWall is moving [only one at a time!]
+        }
+
+        dx = Wolf.Math.dx4dir[dir];
+        dy = Wolf.Math.dy4dir[dir];
+
+        if (level.tileMap[x + dx][y + dy] & (Wolf.SOLID_TILE | Wolf.DOOR_TILE)) {
+            // noway (smth is blocking)
+            return true;
+        }
+
+        // remove secret flag & make everything needed when pushwall used!
+        level.tileMap[x][y] &= (~Wolf.SECRET_TILE);
+        level.tileMap[x][y] &= (~Wolf.WALL_TILE);
+        level.tileMap[x][y] |= Wolf.PUSHWALL_TILE;
+
+        if (++level.state.foundSecrets == level.state.totalSecrets) {
+            Wolf.Game.notify("You found the last secret!");
+        } else {
+            Wolf.Game.notify("You found a secret!");
+        }
+
+        Wolf.Sound.startSound(null, null, 1, Wolf.CHAN_AUTO, "sfx/034.wav", 1, Wolf.ATTN_STATIC, 0);
+
+        // good way to avoid stuckness; [un]comment one more down!
+        // it makes a tile behind pushwall unpassable
+        level.tileMap[x + dx][y + dy] |= Wolf.PUSHWALL_TILE;
+        level.wallTexX[x + dx][y + dy] = level.wallTexX[x][y];
+        level.wallTexY[x + dx][y + dy] = level.wallTexY[x][y];
+
+        // write down PWall info
+        PWall.active = true;
+        PWall.tilesMoved = PWall.pointsMoved = 0;
+        PWall.dir = dir;
+        PWall.x = x;
+        PWall.y = y;
+        PWall.dx = dx;
+        PWall.dy = dy;
+        PWall.texX = level.wallTexX[x][y];
+        PWall.texY = level.wallTexY[x][y];
+
+        return true;
+    }
+
+
+    function process(level, tics) {
+        if (!PWall.active) {
+            return; // no active PWall to work with
+        }
+
+        PWall.pointsMoved += tics;
+        
+        if (PWall.pointsMoved < 128) {
+            return;
+        }
+
+        PWall.pointsMoved -= 128;
+        PWall.tilesMoved++;
+        // Free tile
+        level.tileMap[PWall.x][PWall.y] &= (~Wolf.PUSHWALL_TILE);
+        // Occupy new tile
+        PWall.x += PWall.dx;
+        PWall.y += PWall.dy;
+
+        // Shall we move further?
+        if (level.tileMap[PWall.x + PWall.dx][PWall.y + PWall.dy] & (Wolf.SOLID_TILE | Wolf.DOOR_TILE | Wolf.ACTOR_TILE | Wolf.POWERUP_TILE) || PWall.tilesMoved == 3) {
+            level.tileMap[PWall.x][PWall.y] &= (~Wolf.PUSHWALL_TILE); // wall now
+            level.tileMap[PWall.x][PWall.y] |= Wolf.WALL_TILE; // wall now
+            level.wallTexX[PWall.x][PWall.y] = PWall.texX;
+            level.wallTexY[PWall.x][PWall.y] = PWall.texY;
+            PWall.active = false; // Free Push Wall
+        } else {
+            level.tileMap[PWall.x + PWall.dx][PWall.y + PWall.dy] |= Wolf.PUSHWALL_TILE;
+            
+            // Not sure if this is right but it fixed an issue with the pushwall texture changing mid-slide.
+            level.wallTexX[PWall.x + PWall.dx][PWall.y + PWall.dy] = PWall.texX;
+            level.wallTexY[PWall.x + PWall.dx][PWall.y + PWall.dy] = PWall.texY;
+        }
+    }
+    
+    function get() {
+        return PWall;
+    }
+
+    return {
+        reset : reset,
+        process : process,
+        push : push,
+        get : get
+    };
+
+})();