Author: markt
Date: Tue Mar 6 15:14:50 2012
New Revision: 1297520
URL: http://svn.apache.org/viewvc?rev=1297520&view=rev
Log:
Add a multi-player snake example for WebSocket.
Patch provide by Johno Crawford.
Added:
tomcat/trunk/webapps/examples/WEB-INF/classes/websocket/snake/
tomcat/trunk/webapps/examples/WEB-INF/classes/websocket/snake/Direction.java
tomcat/trunk/webapps/examples/WEB-INF/classes/websocket/snake/Location.java
tomcat/trunk/webapps/examples/WEB-INF/classes/websocket/snake/Snake.java
tomcat/trunk/webapps/examples/WEB-INF/classes/websocket/snake/SnakeWebSocketServlet.java
tomcat/trunk/webapps/examples/websocket/snake.html
Modified:
tomcat/trunk/webapps/examples/WEB-INF/web.xml
tomcat/trunk/webapps/examples/websocket/echo.html
tomcat/trunk/webapps/examples/websocket/index.html
Added:
tomcat/trunk/webapps/examples/WEB-INF/classes/websocket/snake/Direction.java
URL:
http://svn.apache.org/viewvc/tomcat/trunk/webapps/examples/WEB-INF/classes/websocket/snake/Direction.java?rev=1297520&view=auto
==============================================================================
---
tomcat/trunk/webapps/examples/WEB-INF/classes/websocket/snake/Direction.java
(added)
+++
tomcat/trunk/webapps/examples/WEB-INF/classes/websocket/snake/Direction.java
Tue Mar 6 15:14:50 2012
@@ -0,0 +1,21 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package websocket.snake;
+
+public enum Direction {
+ NONE, NORTH, SOUTH, EAST, WEST
+}
Added:
tomcat/trunk/webapps/examples/WEB-INF/classes/websocket/snake/Location.java
URL:
http://svn.apache.org/viewvc/tomcat/trunk/webapps/examples/WEB-INF/classes/websocket/snake/Location.java?rev=1297520&view=auto
==============================================================================
--- tomcat/trunk/webapps/examples/WEB-INF/classes/websocket/snake/Location.java
(added)
+++ tomcat/trunk/webapps/examples/WEB-INF/classes/websocket/snake/Location.java
Tue Mar 6 15:14:50 2012
@@ -0,0 +1,65 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package websocket.snake;
+
+public class Location {
+
+ public int x;
+ public int y;
+
+ public Location(int x, int y) {
+ this.x = x;
+ this.y = y;
+ }
+
+ public Location getAdjacentLocation(Direction direction) {
+ switch (direction) {
+ case NORTH:
+ return new Location(x, y - SnakeWebSocketServlet.GRID_SIZE);
+ case SOUTH:
+ return new Location(x, y + SnakeWebSocketServlet.GRID_SIZE);
+ case EAST:
+ return new Location(x + SnakeWebSocketServlet.GRID_SIZE, y);
+ case WEST:
+ return new Location(x - SnakeWebSocketServlet.GRID_SIZE, y);
+ case NONE:
+ // fall through
+ default:
+ return this;
+ }
+ }
+
+ @Override
+ public boolean equals(Object o) {
+ if (this == o) return true;
+ if (o == null || getClass() != o.getClass()) return false;
+
+ Location location = (Location) o;
+
+ if (x != location.x) return false;
+ if (y != location.y) return false;
+
+ return true;
+ }
+
+ @Override
+ public int hashCode() {
+ int result = x;
+ result = 31 * result + y;
+ return result;
+ }
+}
Added: tomcat/trunk/webapps/examples/WEB-INF/classes/websocket/snake/Snake.java
URL:
http://svn.apache.org/viewvc/tomcat/trunk/webapps/examples/WEB-INF/classes/websocket/snake/Snake.java?rev=1297520&view=auto
==============================================================================
--- tomcat/trunk/webapps/examples/WEB-INF/classes/websocket/snake/Snake.java
(added)
+++ tomcat/trunk/webapps/examples/WEB-INF/classes/websocket/snake/Snake.java
Tue Mar 6 15:14:50 2012
@@ -0,0 +1,142 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package websocket.snake;
+
+import java.io.IOException;
+import java.nio.CharBuffer;
+import java.util.ArrayDeque;
+import java.util.Collection;
+import java.util.Deque;
+import java.util.Iterator;
+
+import org.apache.catalina.websocket.WsOutbound;
+
+public class Snake {
+
+ private static final int DEFAULT_LENGTH = 6;
+
+ private final int id;
+ private final WsOutbound outbound;
+
+ private Direction direction;
+ private Deque<Location> locations = new ArrayDeque<Location>();
+ private String hexColor;
+
+ public Snake(int id, WsOutbound outbound) {
+ this.id = id;
+ this.outbound = outbound;
+ this.hexColor = SnakeWebSocketServlet.getRandomHexColor();
+ resetState();
+ }
+
+ private void resetState() {
+ this.direction = Direction.NONE;
+ this.locations.clear();
+ Location startLocation = SnakeWebSocketServlet.getRandomLocation();
+ for (int i = 0; i < DEFAULT_LENGTH; i++) {
+ locations.add(startLocation);
+ }
+ }
+
+ private void kill() {
+ resetState();
+ try {
+ CharBuffer response = CharBuffer.wrap("{'type': 'dead'}");
+ outbound.writeTextMessage(response);
+ } catch (IOException ioe) {
+ // Ignore
+ }
+ }
+
+ private void reward() {
+ grow();
+ try {
+ CharBuffer response = CharBuffer.wrap("{'type': 'kill'}");
+ outbound.writeTextMessage(response);
+ } catch (IOException ioe) {
+ // Ignore
+ }
+ }
+
+ public synchronized void update(Collection<Snake> snakes) {
+ Location firstLocation = locations.getFirst();
+ Location nextLocation = firstLocation.getAdjacentLocation(direction);
+ if (nextLocation.x >= SnakeWebSocketServlet.PLAYFIELD_WIDTH) {
+ nextLocation.x = 0;
+ }
+ if (nextLocation.y >= SnakeWebSocketServlet.PLAYFIELD_HEIGHT) {
+ nextLocation.y = 0;
+ }
+ if (nextLocation.x < 0) {
+ nextLocation.x = SnakeWebSocketServlet.PLAYFIELD_WIDTH;
+ }
+ if (nextLocation.y < 0) {
+ nextLocation.y = SnakeWebSocketServlet.PLAYFIELD_HEIGHT;
+ }
+ locations.addFirst(nextLocation);
+ locations.removeLast();
+
+ for (Snake snake : snakes) {
+ if (snake.getId() != getId() &&
+ colliding(snake.getHeadLocation())) {
+ snake.kill();
+ reward();
+ }
+ }
+ }
+
+ private void grow() {
+ Location lastLocation = locations.getLast();
+ Location newLocation = new Location(lastLocation.x, lastLocation.y);
+ locations.add(newLocation);
+ }
+
+ private boolean colliding(Location location) {
+ return direction != Direction.NONE && locations.contains(location);
+ }
+
+ public void setDirection(Direction direction) {
+ this.direction = direction;
+ }
+
+ public synchronized String getLocationsJson() {
+ StringBuilder sb = new StringBuilder();
+ for (Iterator<Location> iterator = locations.iterator();
+ iterator.hasNext();) {
+ Location location = iterator.next();
+ sb.append(String.format("{x: %d, y: %d}",
+ Integer.valueOf(location.x), Integer.valueOf(location.y)));
+ if (iterator.hasNext()) {
+ sb.append(',');
+ }
+ }
+ return String.format("{'id':%d,'body':[%s]}",
+ Integer.valueOf(id), sb.toString());
+ }
+
+ public int getId() {
+ return id;
+ }
+
+ public String getHexColor() {
+ return hexColor;
+ }
+
+ public synchronized Location getHeadLocation() {
+ return locations.getFirst();
+ }
+}
Added:
tomcat/trunk/webapps/examples/WEB-INF/classes/websocket/snake/SnakeWebSocketServlet.java
URL:
http://svn.apache.org/viewvc/tomcat/trunk/webapps/examples/WEB-INF/classes/websocket/snake/SnakeWebSocketServlet.java?rev=1297520&view=auto
==============================================================================
---
tomcat/trunk/webapps/examples/WEB-INF/classes/websocket/snake/SnakeWebSocketServlet.java
(added)
+++
tomcat/trunk/webapps/examples/WEB-INF/classes/websocket/snake/SnakeWebSocketServlet.java
Tue Mar 6 15:14:50 2012
@@ -0,0 +1,210 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package websocket.snake;
+
+import java.awt.Color;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.CharBuffer;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.Random;
+import java.util.Timer;
+import java.util.TimerTask;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import javax.servlet.ServletException;
+
+import org.apache.catalina.websocket.MessageInbound;
+import org.apache.catalina.websocket.StreamInbound;
+import org.apache.catalina.websocket.WebSocketServlet;
+import org.apache.catalina.websocket.WsOutbound;
+import org.apache.juli.logging.Log;
+import org.apache.juli.logging.LogFactory;
+
+/**
+ * Example web socket servlet for simple multiplayer snake.
+ */
+public class SnakeWebSocketServlet extends WebSocketServlet {
+
+ private static final long serialVersionUID = 1L;
+
+ private static final Log log =
+ LogFactory.getLog(SnakeWebSocketServlet.class);
+
+ public static final int PLAYFIELD_WIDTH = 640;
+ public static final int PLAYFIELD_HEIGHT = 480;
+ public static final int GRID_SIZE = 10;
+
+ private static final long TICK_DELAY = 100;
+
+ private static final Random random = new Random();
+
+ private final Timer gameTimer =
+ new Timer(SnakeWebSocketServlet.class.getSimpleName() + " Timer");
+
+ private final AtomicInteger connectionIds = new AtomicInteger(0);
+ private final ConcurrentHashMap<Integer, Snake> snakes =
+ new ConcurrentHashMap<Integer, Snake>();
+ private final ConcurrentHashMap<Integer, SnakeMessageInbound> connections =
+ new ConcurrentHashMap<Integer, SnakeMessageInbound>();
+
+ @Override
+ public void init() throws ServletException {
+ super.init();
+ gameTimer.scheduleAtFixedRate(new TimerTask() {
+ @Override
+ public void run() {
+ try {
+ tick();
+ } catch (RuntimeException e) {
+ log.error("Caught to prevent timer from shutting down", e);
+ }
+ }
+ }, TICK_DELAY, TICK_DELAY);
+ }
+
+ private void tick() {
+ StringBuilder sb = new StringBuilder();
+ for (Iterator<Snake> iterator = getSnakes().iterator();
+ iterator.hasNext();) {
+ Snake snake = iterator.next();
+ snake.update(getSnakes());
+ sb.append(snake.getLocationsJson());
+ if (iterator.hasNext()) {
+ sb.append(',');
+ }
+ }
+ broadcast(String.format("{'type': 'update', 'data' : [%s]}",
+ sb.toString()));
+ }
+
+ private void broadcast(String message) {
+ for (SnakeMessageInbound connection : getConnections()) {
+ try {
+ CharBuffer response = CharBuffer.wrap(message);
+ connection.getWsOutbound().writeTextMessage(response);
+ } catch (IOException ignore) {
+ }
+ }
+ }
+
+ private Collection<SnakeMessageInbound> getConnections() {
+ return Collections.unmodifiableCollection(connections.values());
+ }
+
+ private Collection<Snake> getSnakes() {
+ return Collections.unmodifiableCollection(snakes.values());
+ }
+
+ public static String getRandomHexColor() {
+ float hue = random.nextFloat();
+ // sat between 0.1 and 0.3
+ float saturation = (random.nextInt(2000) + 1000) / 10000f;
+ float luminance = 0.9f;
+ Color color = Color.getHSBColor(hue, saturation, luminance);
+ return '#' + Integer.toHexString(
+ (color.getRGB() & 0xffffff) | 0x1000000).substring(1);
+ }
+
+ public static Location getRandomLocation() {
+ int x = roundByGridSize(
+ random.nextInt(SnakeWebSocketServlet.PLAYFIELD_WIDTH));
+ int y = roundByGridSize(
+ random.nextInt(SnakeWebSocketServlet.PLAYFIELD_HEIGHT));
+ return new Location(x, y);
+ }
+
+ private static int roundByGridSize(int value) {
+ value = value + (SnakeWebSocketServlet.GRID_SIZE / 2);
+ value = value / SnakeWebSocketServlet.GRID_SIZE;
+ value = value * SnakeWebSocketServlet.GRID_SIZE;
+ return value;
+ }
+
+ @Override
+ public void destroy() {
+ super.destroy();
+ if (gameTimer != null) {
+ gameTimer.cancel();
+ }
+ }
+
+ @Override
+ protected StreamInbound createWebSocketInbound(String subProtocol) {
+ return new SnakeMessageInbound(connectionIds.incrementAndGet());
+ }
+
+ private final class SnakeMessageInbound extends MessageInbound {
+
+ private final int id;
+ private Snake snake;
+
+ private SnakeMessageInbound(int id) {
+ this.id = id;
+ }
+
+ @Override
+ protected void onOpen(WsOutbound outbound) {
+ this.snake = new Snake(id, outbound);
+ snakes.put(Integer.valueOf(id), snake);
+ connections.put(Integer.valueOf(id), this);
+ StringBuilder sb = new StringBuilder();
+ for (Iterator<Snake> iterator = getSnakes().iterator();
+ iterator.hasNext();) {
+ Snake snake = iterator.next();
+ sb.append(String.format("{id: %d, color: '%s'}",
+ Integer.valueOf(snake.getId()), snake.getHexColor()));
+ if (iterator.hasNext()) {
+ sb.append(',');
+ }
+ }
+ broadcast(String.format("{'type': 'join','data':[%s]}",
+ sb.toString()));
+ }
+
+ @Override
+ protected void onClose(int status) {
+ connections.remove(Integer.valueOf(id));
+ snakes.remove(Integer.valueOf(id));
+ broadcast(String.format("{'type': 'leave', 'id': %d}",
+ Integer.valueOf(id)));
+ }
+
+ @Override
+ protected void onBinaryMessage(ByteBuffer message) throws IOException {
+ throw new UnsupportedOperationException(
+ "Binary message not supported.");
+ }
+
+ @Override
+ protected void onTextMessage(CharBuffer charBuffer) throws IOException
{
+ String message = charBuffer.toString();
+ if ("left".equals(message)) {
+ snake.setDirection(Direction.WEST);
+ } else if ("up".equals(message)) {
+ snake.setDirection(Direction.NORTH);
+ } else if ("right".equals(message)) {
+ snake.setDirection(Direction.EAST);
+ } else if ("down".equals(message)) {
+ snake.setDirection(Direction.SOUTH);
+ }
+ }
+ }
+}
Modified: tomcat/trunk/webapps/examples/WEB-INF/web.xml
URL:
http://svn.apache.org/viewvc/tomcat/trunk/webapps/examples/WEB-INF/web.xml?rev=1297520&r1=1297519&r2=1297520&view=diff
==============================================================================
--- tomcat/trunk/webapps/examples/WEB-INF/web.xml (original)
+++ tomcat/trunk/webapps/examples/WEB-INF/web.xml Tue Mar 6 15:14:50 2012
@@ -377,5 +377,13 @@
<servlet-name>wsEchoMessage</servlet-name>
<url-pattern>/websocket/echoMessage</url-pattern>
</servlet-mapping>
+ <servlet>
+ <servlet-name>wsSnake</servlet-name>
+ <servlet-class>websocket.snake.SnakeWebSocketServlet</servlet-class>
+ </servlet>
+ <servlet-mapping>
+ <servlet-name>wsSnake</servlet-name>
+ <url-pattern>/websocket/snake</url-pattern>
+ </servlet-mapping>
</web-app>
Modified: tomcat/trunk/webapps/examples/websocket/echo.html
URL:
http://svn.apache.org/viewvc/tomcat/trunk/webapps/examples/websocket/echo.html?rev=1297520&r1=1297519&r2=1297520&view=diff
==============================================================================
--- tomcat/trunk/webapps/examples/websocket/echo.html (original)
+++ tomcat/trunk/webapps/examples/websocket/echo.html Tue Mar 6 15:14:50 2012
@@ -30,7 +30,6 @@
#console-container {
float: left;
- margin-left: 20px;
padding-left: 20px;
width: 400px;
}
Modified: tomcat/trunk/webapps/examples/websocket/index.html
URL:
http://svn.apache.org/viewvc/tomcat/trunk/webapps/examples/websocket/index.html?rev=1297520&r1=1297519&r2=1297520&view=diff
==============================================================================
--- tomcat/trunk/webapps/examples/websocket/index.html (original)
+++ tomcat/trunk/webapps/examples/websocket/index.html Tue Mar 6 15:14:50 2012
@@ -24,5 +24,6 @@
<P></P>
<ul>
<li><a href="echo.html">Echo example</a></li>
+<li><a href="snake.html">Multiplayer snake example</a></li>
</ul>
</BODY></HTML>
\ No newline at end of file
Added: tomcat/trunk/webapps/examples/websocket/snake.html
URL:
http://svn.apache.org/viewvc/tomcat/trunk/webapps/examples/websocket/snake.html?rev=1297520&view=auto
==============================================================================
--- tomcat/trunk/webapps/examples/websocket/snake.html (added)
+++ tomcat/trunk/webapps/examples/websocket/snake.html Tue Mar 6 15:14:50 2012
@@ -0,0 +1,244 @@
+<!--
+ Licensed to the Apache Software Foundation (ASF) under one or more
+ contributor license agreements. See the NOTICE file distributed with
+ this work for additional information regarding copyright ownership.
+ The ASF licenses this file to You under the Apache License, Version 2.0
+ (the "License"); you may not use this file except in compliance with
+ the License. You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+-->
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
+ "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd";>
+<html xmlns="http://www.w3.org/1999/xhtml"; lang="en" xml:lang="en">
+<head>
+ <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
+ <title>Apache Tomcat WebSocket Examples: Multiplayer Snake</title>
+ <style type="text/css">
+ #playground {
+ width: 640px;
+ height: 480px;
+ background-color: #000;
+ }
+
+ #console-container {
+ float: left;
+ margin-left: 15px;
+ width: 300px;
+ }
+
+ #console {
+ border: 1px solid #CCCCCC;
+ border-right-color: #999999;
+ border-bottom-color: #999999;
+ height: 480px;
+ overflow-y: scroll;
+ padding-left: 5px;
+ padding-right: 5px;
+ width: 100%;
+ }
+
+ #console p {
+ padding: 0;
+ margin: 0;
+ }
+ </style>
+</head>
+<body>
+ <noscript><h1>Seems your browser doesn't support Javascript! Websockets
rely on Javascript being enabled. Please enable
+ Javascript and reload this page!</h1></noscript>
+ <div style="float: left">
+ <canvas id="playground" width="640" height="480"></canvas>
+ </div>
+ <div id="console-container">
+ <div id="console"></div>
+ </div>
+ <script type="text/javascript">
+
+ var Game = {};
+
+ Game.fps = 30;
+ Game.socket = null;
+ Game.nextFrame = null;
+ Game.interval = null;
+ Game.gridSize = 10;
+
+ function Snake() {
+ this.snakeBody = [];
+ this.color = null;
+ }
+
+ Snake.prototype.draw = function(context) {
+ for (var id in this.snakeBody) {
+ context.fillStyle = this.color;
+ context.fillRect(this.snakeBody[id].x, this.snakeBody[id].y,
Game.gridSize, Game.gridSize);
+ }
+ };
+
+ Game.initialize = function() {
+ this.entities = [];
+ canvas = document.getElementById('playground');
+ if (!canvas.getContext) {
+ Console.log('Error: 2d canvas not supported by this browser.');
+ return;
+ }
+ this.context = canvas.getContext('2d');
+ window.addEventListener('keydown', function (e) {
+ var code = e.keyCode;
+ if (code > 36 && code < 41) {
+ switch (code) {
+ case 37:
+ Game.socket.send('left');
+ break;
+ case 38:
+ Game.socket.send('up');
+ break;
+ case 39:
+ Game.socket.send('right');
+ break;
+ case 40:
+ Game.socket.send('down');
+ break;
+ }
+ Console.log('Sent: keyCode ' + code);
+ }
+ }, false);
+ Game.connect('ws://' + window.location.host +
'/examples/websocket/snake');
+ };
+
+ Game.startGameLoop = function() {
+ if (window.webkitRequestAnimationFrame) {
+ Game.nextFrame = function () {
+ webkitRequestAnimationFrame(Game.run);
+ };
+ } else if (window.mozRequestAnimationFrame) {
+ Game.nextFrame = function () {
+ mozRequestAnimationFrame(Game.run);
+ };
+ } else {
+ Game.interval = setInterval(Game.run, 1000 / Game.fps);
+ }
+ if (Game.nextFrame != null) {
+ Game.nextFrame();
+ }
+ };
+
+ Game.stopGameLoop = function () {
+ Game.nextFrame = null;
+ if (Game.interval != null) {
+ clearInterval(Game.interval);
+ }
+ };
+
+ Game.draw = function() {
+ this.context.clearRect(0, 0, 640, 480);
+ for (var id in this.entities) {
+ this.entities[id].draw(this.context);
+ }
+ };
+
+ Game.addSnake = function(id, color) {
+ Game.entities[id] = new Snake();
+ Game.entities[id].color = color;
+ };
+
+ Game.updateSnake = function(id, snakeBody) {
+ if (typeof Game.entities[id] != "undefined") {
+ Game.entities[id].snakeBody = snakeBody;
+ }
+ };
+
+ Game.removeSnake = function(id) {
+ Game.entities[id] = null;
+ delete Game.entities[id]; // force GC
+ };
+
+ Game.run = (function() {
+ var skipTicks = 1000 / Game.fps, nextGameTick = (new
Date).getTime();
+
+ return function() {
+ while ((new Date).getTime() > nextGameTick) {
+ nextGameTick += skipTicks;
+ }
+ Game.draw();
+ if (Game.nextFrame != null) {
+ Game.nextFrame();
+ }
+ };
+ })();
+
+ Game.connect = (function(host) {
+ if ('WebSocket' in window) {
+ Game.socket = new WebSocket(host);
+ } else if ('MozWebSocket' in window) {
+ Game.socket = new MozWebSocket(host);
+ } else {
+ Console.log('Error: WebSocket is not supported by this
browser.');
+ return;
+ }
+
+ Game.socket.onopen = function () {
+ // Socket initialised.. start the game loop
+ Console.log('Info: WebSocket connection opened.');
+ Console.log('Info: Press an arrow key to begin.');
+ Game.startGameLoop();
+ setInterval(function() {
+ Game.socket.send('ping'); // prevent server read timeout
+ }, 5000);
+ };
+
+ Game.socket.onclose = function () {
+ Console.log('Info: WebSocket closed.');
+ Game.stopGameLoop();
+ };
+
+ Game.socket.onmessage = function (message) {
+ var packet = eval('(' + message.data + ')'); // Consider using
json lib to parse data.
+ switch (packet.type) {
+ case 'update':
+ for (var i = 0; i < packet.data.length; i++) {
+ Game.updateSnake(packet.data[i].id,
packet.data[i].body);
+ }
+ break;
+ case 'join':
+ for (var j = 0; j < packet.data.length; j++) {
+ Game.addSnake(packet.data[j].id,
packet.data[j].color);
+ }
+ break;
+ case 'leave':
+ Game.removeSnake(packet.id);
+ break;
+ case 'dead':
+ Console.log('Info: Your snake is dead, bad luck!');
+ break;
+ case 'kill':
+ Console.log('Info: Head shot!');
+ break;
+ }
+ };
+ });
+
+ var Console = {};
+
+ Console.log = (function(message) {
+ var console = document.getElementById('console');
+ var p = document.createElement('p');
+ p.style.wordWrap = 'break-word';
+ p.innerHTML = message;
+ console.appendChild(p);
+ while (console.childNodes.length > 25) {
+ console.removeChild(console.firstChild);
+ }
+ console.scrollTop = console.scrollHeight;
+ });
+
+ Game.initialize();
+ </script>
+</body>
+</html>
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