JavaScript異步編程之Jscex制作憤怒的小鳥
作者：趙磊
Jscex真的能制作憤怒的小鳥?在我沒有接觸Jscex之前，我也不相信!但是只要解決了重力場運動和碰撞的兩大物理問題，Jscex版的憤怒小鳥，那就是囊中之物。
Jscex真的能制作憤怒的小鳥?在我沒有接觸Jscex之前，我也不相信!但是只要解決了重力場運動和碰撞的兩大物理問題，Jscex版的憤怒小鳥，那就是囊中之物。
51CTO推薦專題：JavaScript異步編程
如果關注這個系列的話，在javascript異步編程之Jscex模擬重力場與google蘋果logo的比較中，模擬了蘋果在重力場下的自由落體運動。
那么我們可以輕松的幫它擴展一個水平方向上的速度.
- <script type="text/javascript">
- function Bird(startPos, speed_X, speed_Y, element) {
- this.speed_X = speed_X;
- this.speed_Y = speed_Y;
- this.startPos = startPos;
- this.fly = function () {
- flyAsync(element, startPos, speed_X, speed_Y).start();
- }
- }
- var flyAsync = eval(Jscex.compile("async", function (e, startPos, speed_X, speed_Y) {
- e.style.left = startPos.x;
- e.style.top = startPos.y;
- //vt=v0+at
- //重力加速度
- var a_y = 40;
- var speed_Yspeed_YTemp = speed_Y;
- var time = 0;
- while (Math.abs(speed_Y) <= speed_YTemp) {
- $await(Jscex.Async.sleep(50));
- timetime = time + 50;
- speed_Yspeed_Y = speed_Y - a_y;
- startPos.y -= (speed_Y * 0.05);
- e.style.top = startPos.y;
- startPos.x += speed_X * 0.05;
- e.style.left = startPos.x;
- }
- }));
- function Button1_onclick() {
- var bird = new Bird({ x: 0, y: 300 }, 400, 700, document.getElementById("birdDiv"));
- bird.fly();
- }
- </script>
- <input id="Button1" type="button" value="發￠射?" onclick="return Button1_onclick()" />
- <div id="birdDiv" style="left: 0px; top: 300px; position: absolute;">
- <img id="bird" src="bird.jpg" alt="" />
- </div>
可以看得出來，有點生硬，而且位移有點偏差，比如啟始的top:1000,終止的top:1100!主要原因是在結束while (Math.abs(speed_Y) <= speed_YTemp)的之前那最后一次
循環帶來的誤差!那么就完善一下while里面的條件，讓它不執行最后一次循環。
- var flyAsync = eval(Jscex.compile("async", function (e, startPos, speed_X, speed_Y) {
- e.style.left = startPos.x;
- e.style.top = startPos.y;
- //vt=v0+at
- //重力加速度
- var a_y = 40;
- var speed_Yspeed_YTemp = speed_Y;
- var time = 0;
- var maxY = startPos.y
- while (speed_Y > 0 ? (Math.abs(speed_Y) <= speed_YTemp) : (e.offsetTop - (speed_Y - a_y) * 0.05 <= maxY)) {
- $await(Jscex.Async.sleep(50));
- timetime = time + 50;
- speed_Yspeed_Y = speed_Y - a_y;
- startPos.y -= (speed_Y * 0.05);
- e.style.top = startPos.y;
- startPos.x += speed_X * 0.05;
- e.style.left = startPos.x;
- }
- }));
最后讓小鳥撞擊地面彈起，然后又撞擊地面彈起···一直循環下去···
- var flyAsync = eval(Jscex.compile("async", function (e, startPos, speed_X, speed_Y) {
- e.style.left = startPos.x;
- e.style.top = startPos.y;
- var maxY = startPos.y;
- //所用公式?:vt=v0+at
- //重力加速度
- var a_y = 40;
- var speed_Yspeed_YTemp = speed_Y;
- var time = 0;
- while (true) {
- $await(Jscex.Async.sleep(1));
- while (speed_Y > 0 ? (Math.abs(speed_Y) <= speed_YTemp) : (e.offsetTop - (speed_Y - a_y) * 0.05 <= maxY)) {
- $await(Jscex.Async.sleep(50));
- timetime = time + 50;
- speed_Yspeed_Y = speed_Y - a_y;
- startPos.y -= (speed_Y * 0.05);
- e.style.top = startPos.y;
- startPos.x += speed_X * 0.05;
- e.style.left = startPos.x;
- }
- //與地面撞擊，X軸損失一部分速度，Y軸損失一部分速度并且被彈起
- speed_Xspeed_X = speed_X / 2;
- speed_Y = -speed_Y / 3;
- if (speed_X < 6) break;
- }
- }));
因為撞擊的過程當中，X軸損失一部分速度，Y軸損失一部分速度并且被彈起,當speed_X小于6的時候退出循環。
黃色小鳥：體型較小，重量較輕，殊效為加快，應用進步擊弱，應用掉隊擊中等。進擊木頭較強，進擊玻璃與混凝土很弱。
對，沒有錯，它就這這篇文章的主角!
需求解析：沖鋒陷陣鳥，在不點擊加快的景象下，和紅色小鳥樣，當點擊了加快按鈕，X軸標的目標速度變成本來的3倍，Y軸標的目標變成本來的3倍，
沖鋒狀況下速度不受重力影響。
原理圖：
沖鋒鳥代碼實現：
- <script type="text/javascript">
- function Bird(startPos, speed_X, speed_Y, element) {
- this.speed_X = speed_X;
- this.speed_Y = speed_Y;
- this.startPos = startPos;
- this.fly = function () {
- flyAsync(element, startPos, speed_X, speed_Y).start();
- }
- }
- var flyAsync = eval(Jscex.compile("async", function (e, startPos, speed_X, speed_Y) {
- document.getElementById("hdTag").value = 1;
- e.style.left = startPos.x;
- e.style.top = startPos.y;
- var maxY = startPos.y;
- //重?力|加ó速ù度è
- var a_y = 40;
- var speed_Yspeed_YTemp = speed_Y;
- var speed_Xspeed_XTemp = speed_X;
- var time = 0;
- var addTag = 1;
- while (true) {
- $await(Jscex.Async.sleep(1));
- while ((e.offsetTop - (speed_Y - a_y) * 0.05 <= maxY)) {
- if (document.getElementById("hdTag").value == 1) {
- $await(Jscex.Async.sleep(50));
- timetime = time + 50;
- speed_Yspeed_Y = speed_Y - a_y;
- startPos.y -= (speed_Y * 0.05);
- startPos.x += speed_X * 0.05;
- e.style.top = startPos.y + "px";
- e.style.left = startPos.x + "px";
- }
- else {
- //沖?鋒?狀′態?
- $await(Jscex.Async.sleep(50));
- timetime = time + 50;
- if (addTag == 1) {
- addTag = 0;
- //速ù度è翻-倍?
- speed_Y = 3 * speed_Y;
- speed_X = 3 * speed_X;
- }
- startPos.y -= (speed_Y * 0.05);
- startPos.x += speed_X * 0.05;
- e.style.top = startPos.y + "px";
- e.style.left = startPos.x + "px";
- }
- }
- if (addTag == 0) {
- addTag = 1; break;
- }
- //與?地?面?撞2擊÷，?X軸á損e失§一?部?分?速ù度è，?Y軸á損e失§一?部?分?速ù度è并￠且ò被?彈ˉ起e
- document.getElementById("hdTag").value = 1;
- speed_Xspeed_X = speed_X / 2;
- speed_Y = -speed_Y / 3;
- if (speed_X < 6) break;
- }
- }));
- function Button1_onclick() {
- var bird = new Bird({ x: 0, y: 500 }, 400, 700, document.getElementById("birdDiv"));
- bird.fly();
- }
- function Button2_onclick() {
- document.getElementById("hdTag").value = 0;
- }
- </script>
- <div >
- <input id="hdTag" value="1" type="hidden" />
- <input id="Button1" type="button" value="發￠射?" onclick="return Button1_onclick()" />
- <input id="Button2" type="button" value="加ó速ù" onclick="return Button2_onclick()" />
- <div id="birdDiv" style="left: 0px; top: 500px; position: absolute; width: 20px;
- height: 30px;z-index:10;">
- <img src="yellowbird.png" alt=""/>
- </div>
- </div>
最新的Jscex 庫，請上https://github.com/JeffreyZhao/jscex或者http://www.sndacode.com/projects/jscex/wiki下載吧····
原文：http://www.cnblogs.com/iamzhanglei/archive/2011/08/24/2151473.html
【系列文章】
責任編輯：陳貽新
來源：
趙磊的博客
