用HTML5制作一個(gè)簡(jiǎn)單的桌球游戲的教程

2020-03-24 16:15:03

字體：大中小

供稿：網(wǎng)友

話說(shuō)這只是一個(gè)簡(jiǎn)單的DEMO。游戲性，游戲規(guī)則什么的我都沒(méi)怎么考慮，如果有興趣細(xì)化的朋友可以細(xì)化一下，比如細(xì)化一下規(guī)則，游戲開(kāi)關(guān)，加個(gè)聲音，細(xì)化一下進(jìn)球檢測(cè)，更嚴(yán)謹(jǐn)甚至可以去查下?lián)羟蛄Χ取⒆烂嬲鎸?shí)摩擦力等來(lái)把游戲弄的更像游戲。我只是給個(gè)編程思路哈，隨便坐個(gè)DEMO而已，玩起來(lái)估計(jì)還是不會(huì)很爽快的~~
關(guān)于簡(jiǎn)單的碰撞檢測(cè) 岑安大大講的還是很好的。好，接下來(lái)就一步一步來(lái)：【球】先貼代碼：
[/code]var Ball = function(x , y , ismine){
this.x = x;
this.y = y;
this.ismine = ismine;
this.oldx = x;
this.oldy = y;
this.vx = 0;
this.vy = 0;
this.radius = ballRadius;
this.inhole = false;this.moving = true;
}
Ball.prototype = {
constructor:Ball,
_paint:function(){
var b = this.ismine?document.getElementById( wb ) : document.getElementById( yb )
if(b.complete) {
ctx.drawImage(b , this.x-this.radius , this.y-this.radius , 2*this.radius , 2*this.radius);
}
else {
b.onload = function(){
ctx.drawImage(b , this.x-this.radius , this.y-this.radius , 2*this.radius , 2*this.radius);
}
}
},
_run:function(t){
this.oldx = this.x;
this.oldy = this.y; this.vx = Math.abs(this.vx) 0.1? 0 : (this.vx 0? this.vx-mcl*t : this.vx+mcl*t);
this.vy = Math.abs(this.vy) 0.1? 0 : (this.vy 0? this.vy-mcl*t : this.vy+mcl*t);
// this.vx += this.vx 0? -mcl*t : mcl*t;
// this.vy += this.vy 0? -mcl*t : mcl*t; this.x += t * this.vx * pxpm;
this.y += t * this.vy * pxpm; if((this.x 50 this.y 50) || (this.x 370 this.x 430 this.y 50) || (this.x 758 this.y 50) || (this.x 46 this.y 490) || (this.x 377 this.x 420 this.y 490) || (this.x 758 this.y 490)){
this.inhole = true;
if(this.ismine){
var that = this;
setTimeout(function(){
that.x = 202;
that.y = canvas.height/2;
that.vx = 0;
that.vy = 0;
that.inhole = false;
} , 500)
}
else {
document.getElementById( shotNum ).innerHTML = parseInt(document.getElementById( shotNum ).innerHTML)+1
}
}
else {
if(this.y canvas.height - (ballRadius+tbw) || this.y (ballRadius+tbw)){
this.y = this.y (ballRadius+tbw) ? (ballRadius+tbw) : (canvas.height - (ballRadius+tbw));
this.derectionY = !this.derectionY;
this.vy = -this.vy*0.6;
}
if(this.x canvas.width - (ballRadius+tbw) || this.x (ballRadius+tbw)){
this.x = this.x (ballRadius+tbw) ? (ballRadius+tbw) : (canvas.width - (ballRadius+tbw));
this.derectionX = !this.derectionX;
this.vx = -this.vx*0.6;
}
}
this._paint(); if(Math.abs(this.vx) 0.1 Math.abs(this.vy) 0.1){
this.moving = false;
}
else {
this.moving = true;
}
}
}[/code]
球類的屬性：x,y球的位置，vx,vy球的水平速度以及求得垂直速度，ismine代表是白球還是其他球（不同球在_paint方法中繪制的圖片不一樣），oldx,oldy用于保存球的上一幀位置，不過(guò)暫時(shí)還沒(méi)用上，應(yīng)該有用吧。_paint方法沒(méi)什么好說(shuō)的，_run方法就是跟蹤小球位置，根據(jù)小球每一幀的時(shí)間來(lái)算出小球的位移增量以及速度增量，mcl和pxpm都是常量，mcl是摩擦力，pxpm是大概算個(gè)像素和現(xiàn)實(shí)轉(zhuǎn)換比例。。。。然后就是碰撞檢測(cè)，這個(gè)很容易理解了，就計(jì)算小球的位置有沒(méi)有超過(guò)邊界，超過(guò)了就反彈。不過(guò)這種碰撞檢測(cè)很不嚴(yán)謹(jǐn)，如果真要做游戲建議用更復(fù)雜一些的。還有就是根據(jù)小球的速度來(lái)讓小球靜止。

復(fù)制代碼代碼如下:var dotLine = function(x0,y0,x1,y1){
this.x0 = this.x0;
this.y0 = this.y0;
this.x1 = this.x1;
this.y1 = this.y1;
this.dotlength = 3;
this.display = false;
}
dotLine.prototype = {
constructor:dotLine,
_ready:function(){
this.length = Math.sqrt(Math.pow(this.y1 - this.y0 , 2)+Math.pow(this.x1 - this.x0 , 2));
this.dotNum = Math.ceil(this.length/this.dotlength);
},
_paint:function(){
this._ready();
xadd = this.dotlength*(this.x1 - this.x0)/this.length;
yadd = this.dotlength*(this.y1 - this.y0)/this.length;
ctx.save();
ctx.beginPath();
for(var i=1;i =this.dotNum;i++){
if(i%2!==0){
ctx.moveTo(this.x0+(i-1)*xadd , this.y0+(i-1)*yadd);
ctx.lineTo(this.x0+i*xadd , this.y0+i*yadd);
}
}
ctx.strokeStyle = "#FFF";
ctx.stroke();
ctx.beginPath();
ctx.arc(this.x1 , this.y1 , ballRadius-2 , 0 , 2*Math.PI);
ctx.stroke();
ctx.restore();
}
}
就是畫(huà)虛線，這個(gè)比較簡(jiǎn)單了，獲取鼠標(biāo)的位置和白球位置，然后在兩者之間隔一段距離畫(huà)條線，然后就成虛線了。【多球碰撞檢測(cè)】

復(fù)制代碼代碼如下:function collision(){
for(var i=0;i balls.length;i++){
for(var j=0;j balls.length;j++){
var b1 = balls[i],b2 = balls[j];
if(b1 !== b2 !b1.inhole !b2.inhole){
var rc = Math.sqrt(Math.pow(b1.x - b2.x , 2) + Math.pow(b1.y - b2.y , 2));
if(Math.ceil(rc) (b1.radius + b2.radius)){
if(!b1.moving !b2.moving) return;
//獲取碰撞后的速度增量
var ax = ((b1.vx - b2.vx)*Math.pow((b1.x - b2.x) , 2) + (b1.vy - b2.vy)*(b1.x - b2.x)*(b1.y - b2.y))/Math.pow(rc , 2)
var ay = ((b1.vy - b2.vy)*Math.pow((b1.y - b2.y) , 2) + (b1.vx - b2.vx)*(b1.x - b2.x)*(b1.y - b2.y))/Math.pow(rc , 2)
//將速度增量賦給碰撞小球
b1.vx = b1.vx-ax;
b1.vy = b1.vy-ay;
b2.vx = b2.vx+ax;
b2.vy = b2.vy+ay;
//修正小球碰撞距離
var clength = ((b1.radius+b2.radius)-rc)/2;
var cx = clength * (b1.x-b2.x)/rc;
var cy = clength * (b1.y-b2.y)/rc;
b1.x = b1.x+cx;
b1.y = b1.y+cy;
b2.x = b2.x-cx;
b2.y = b2.y-cy;
}
}
}
}
}
對(duì)所有小球進(jìn)行遍歷，計(jì)算兩個(gè)小球的球心距離，如果小于兩小球的半徑和，則說(shuō)明發(fā)生了碰撞。如果兩個(gè)小球都是靜止的，就不進(jìn)行碰撞檢測(cè)，否則進(jìn)行計(jì)算碰撞后的速度增量，碰撞速度增量的求法可以直接看小球碰撞的算法設(shè)計(jì) ，里面講的挺詳細(xì)的，綜合起來(lái)就得出了上面那一串式子了。將速度增量賦給碰撞小球。因?yàn)閮蓚€(gè)球碰撞那一幀，兩個(gè)球是有部分重疊的，所以得進(jìn)行位置修正，不然小球會(huì)一直處于碰撞然后就黏在一起了，位置修正的原理也簡(jiǎn)單，算出兩球的球心距離，通過(guò)勾股定理計(jì)算出兩球的重疊區(qū)域的寬度，然后把寬度除于2后賦給小球新的位置，新的位置就是兩個(gè)球的半徑剛好等于球心距。【鼠標(biāo)動(dòng)作】

復(fù)制代碼代碼如下:canvas.addEventListener("mousedown" , function(){
if(balls[0].moving) return; /p p document.querySelector(".shotPower").style.display = "block";
document.querySelector(".shotPower").style.top = balls[0].y-60 + "px";
document.querySelector(".shotPower").style.left = balls[0].x-40 +"px";
document.getElementById("pow").html' target='_blank'>className = "animate";
var x = event.clientX + document.body.scrollLeft + document.documentElement.scrollLeft - document.querySelector(".view").offsetLeft;
var y = event.clientY + document.body.scrollTop + document.documentElement.scrollTop - document.querySelector(".view").offsetTop;
dotline.display = true;
dotline.x0 = balls[0].x;
dotline.y0 = balls[0].y;
dotline.x1 = x;
dotline.y1 = y; /p p window.addEventListener("mouseup" , muHandle , false);
window.addEventListener("mousemove" , mmHandle , false); /p p function mmHandle(){
var x = event.clientX + document.body.scrollLeft + document.documentElement.scrollLeft - document.querySelector(".view").offsetLeft;
var y = event.clientY + document.body.scrollTop + document.documentElement.scrollTop - document.querySelector(".view").offsetTop;
dotline.x1 = x;
dotline.y1 = y;
}
function muHandle(){
var x = event.clientX + document.body.scrollLeft + document.documentElement.scrollLeft - document.querySelector(".view").offsetLeft;
var y = event.clientY + document.body.scrollTop + document.documentElement.scrollTop - document.querySelector(".view").offsetTop; /p p var angle = Math.atan((y - balls[0].y)/(x - balls[0].x));
var h = document.getElementById("pow").offsetHeight/document.getElementById("powbar").offsetHeight;
var v = 60*h;
document.getElementById("pow").style.height = h*100+"%" /p p balls[0].vx = x - balls[0].x 0 ? v*Math.abs(Math.cos(angle)) : -v*Math.abs(Math.cos(angle));
balls[0].vy = y - balls[0].y 0 ? v*Math.abs(Math.sin(angle)) : -v*Math.abs(Math.sin(angle)); /p p document.getElementById("pow").className = ""; /p p window.removeEventListener("mouseup" , muHandle , false);
window.removeEventListener("mousemove" , muHandle , false);
dotline.display = false;
document.querySelector(".shotPower").style.display = "none";
}
},false);
鼠標(biāo)動(dòng)作也比較簡(jiǎn)單，有js基礎(chǔ)的基本上都沒(méi)問(wèn)題，就是鼠標(biāo)按下后計(jì)算鼠標(biāo)位置，然后產(chǎn)生輔助虛線，鼠標(biāo)移動(dòng)后修改輔助虛線的終點(diǎn)位置。鼠標(biāo)按下的時(shí)候旁邊產(chǎn)生一個(gè)力量計(jì)，我就只用用animation做動(dòng)畫(huà)了，然后鼠標(biāo)按鍵抬起時(shí)通過(guò)計(jì)算力量計(jì)的大小來(lái)確定白球的速度，然后再分解成水平速度以及垂直速度賦給白球。同時(shí)取消鼠標(biāo)移動(dòng)以及鼠標(biāo)抬起的事件綁定，把輔助虛線以及力量計(jì)隱藏。【動(dòng)畫(huà)舞臺(tái)】
復(fù)制代碼代碼如下: function animate(){
ctx.clearRect(0,0,canvas.width,canvas.height)
var t1 = new Date();
var t = (t1 - t0)/1000; /p p collision();
balls.foreach(function(){
if(!this.inhole) this._run(t);
});
if(dotline.display){
dotline.x0 = balls[0].x;
dotline.y0 = balls[0].y;
dotline._paint();
} /p p t0 = t1;
if(!animateStop){
if("requestAnimationFrame" in window){
requestAnimationFrame(animate);
}
else if("webkitRequestAnimationFrame" in window){
webkitRequestAnimationFrame(animate);
}
else if("msRequestAnimationFrame" in window){
msRequestAnimationFrame(animate);
}
else if("mozRequestAnimationFrame" in window){
mozRequestAnimationFrame(animate);
}
else {
setTimeout(animate , 16);
}
}
}
這個(gè)就是游戲每一幀的邏輯處理現(xiàn)場(chǎng)，如果小球進(jìn)洞了，就不再進(jìn)行繪制，如果輔助虛線的display屬性設(shè)成false，就不進(jìn)行輔助虛線的繪制，還有就是計(jì)算每一幀的時(shí)間。【常量與初始化】

復(fù)制代碼代碼如下:
var canvas = document.getElementById("cas");
var ctx = canvas.getContext('2d');
var mcl = 1 , collarg = 0.8 , ballRadius = 15 , t0 = 0 , balls=[] , tbw = 32 , animateStop = true , powAnimation = false;
var dotline;
pxpm = canvas.width/20; /p p window.onload = function(){
var myball = new Ball(202 , canvas.height/2 , true);
balls.push(myball);
for(var i=0;i i++){
for(var j=0;j j++){
var other = new Ball(520+i*(ballRadius-2)*2 , (canvas.height-i*2*ballRadius)/2+ballRadius+2*ballRadius*j , false);
balls.push(other);
}
}
t0 = new Date();
dotline = new dotLine(0,0,0,0); /p p animateStop = false;
animate();
}
實(shí)例化所有小球，把小球全部按照規(guī)律擺好，然后獲取當(dāng)前時(shí)間，實(shí)例化輔助虛線，動(dòng)畫(huà)開(kāi)始。源碼地址：http://github.com/whxaxes/canvas-test/tree/gh-pages/src/Game-demo/snooker
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