Javascript 我想从数组中在画布上画一个圆？
我希望能够从在画布上画一个圆圈开始，然后推到一个数组上。这是行不通的Javascript 我想从数组中在画布上画一个圆？,javascript,canvas,Javascript,Canvas,我希望能够从在画布上画一个圆圈开始，然后推到一个数组上。这是行不通的 function Circle(x, y, r){ this.x = x; this.y = y; this.r = r; } // create an array var anArray = []; // make a circle instance var aCircle = new Circle(100, 100, 20)
function Circle(x, y, r){
this.x = x;
this.y = y;
this.r = r;
}
// create an array
var anArray = [];
// make a circle instance
var aCircle = new Circle(100, 100, 20);
//add it to the array
anArray.push(aCircle);
function drawCircle() {
context.beginPath();
context.arc(anArry[0].x,anArry[0].y,anArry[0].r,0,Math.PI*2,true);
context.closePath();
context.fill();
帆布{
边框：5px实心#999；
背景色：#000000；
}
var语境；
var rightKey=false；
var leftKey=false；
var-upKey=false；
var downKey=false；
var块x；
var块y；
var block_h=15；
var块w=15；
var imageObj=新图像（）；
imageObj.src='spaceShip.jpg'；
函数圆（x，y，r）{
这个.x=x；
这个。y=y；
这个。r=r；
}
//创建一个数组
var anArray=[]；
//做一个圆的例子
var aCircle=新的圆（100,100,20）；
//将其添加到数组中
推（一圈）；
函数drawCircle（）{
context.beginPath（）；
arc（anArry[0].x，anArry[0].y，anArry[0].r，0，Math.PI*2，true）；
closePath（）；
context.fill（）；
/*
对于（var i=0；i您的drawCircle（）方法（anArryanArray）中有语法错误，下面是适用于我的更新代码：
function drawCircle() {
context.beginPath();
context.arc(anArray[0].x, anArray[0].y, anArray[0].r, 0, Math.PI*2, false);
context.fillStyle = 'yellow';
context.fill();
//context.closePath();
/*
for(var i=0; i<numCircle; i++) {
canvasContext.fillStyle='#123321;'
drawCircle(anArry[0].x,anArry[0].y,anArry[0].r,canvasContext);
}
*/
}
函数drawCircle（）{
context.beginPath（）；
arc（anArray[0].x，anArray[0].y，anArray[0].r，0，Math.PI*2，false）；
context.fillStyle='yellow'；
context.fill（）；
//closePath（）；
/*
对于（var i=0；iSo），您的圆是什么颜色？
<!DOCTYPE HTML>
<html>
<head>
<style>
canvas {
border: 5px solid #999;
background-color: #000000;
}
</style>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.1/jquery.min.js" type="text/javascript"></script>
</head>
<body>
<canvas id="myCanvas" width="450" height="610" style="border:3px solid #c3c3c3;">
</canvas>
<script>
var context;
var rightKey = false;
var leftKey = false;
var upKey = false;
var downKey = false;
var block_x;
var block_y;
var block_h = 15;
var block_w = 15;
var shipCnt = 4; //keeps track of the number of ships that the player has left
var levelCnt = 1; //keeps track of which level the player is on so that the correct colored mushroom is displayed
var PLAYERNUM = 'PLAYER 1';
var READY = 'READY!'; //Used to display on the start of every new life
var imageObj = new Image();
imageObj.src = 'spaceShip.jpg';
function Circle(x, y, r){
this.x = x;
this.y = y;
this.r = r;
}
// create an array
var anArray = [];
// make a circle instance
var aCircle = new Circle(100, 100, 20);
//add it to the array
anArray.push(aCircle);
function drawCircle() {
context.beginPath();
context.arc(anArray[0].x, anArray[0].y, anArray[0].r, 0, Math.PI*2, false);
context.fillStyle = 'yellow';
context.fill();
//context.closePath();
/*
for(var i=0; i<numCircle; i++) {
canvasContext.fillStyle='#123321;'
drawCircle(anArry[0].x,anArry[0].y,anArry[0].r,canvasContext);
}
*/
}
function drawScore() {
context.fillStyle = "red";
context.font = "bold 16px Arial";
context.fillText("1000", 5, 15);
context.fillStyle = "red";
context.font = "bold 16px Arial";
context.fillText("14500", 200, 15);
}
function drawExtraLives() {
context.drawImage(imageObj, 45, 3);
context.drawImage(imageObj, 60, 3);
context.drawImage(imageObj, 75, 3);
}
function drawPlayerOne() {
context.fillStyle = "yellow";
context.font = "bold 20px Arial";
context.fillText(PLAYERNUM, 175, 260);
}
function drawReady() {
context.fillStyle = "yellow";
context.font = "bold 20px Arial";
context.fillText(READY, 185, 280);
}
function init() {
context = $('#myCanvas')[0].getContext('2d');
WIDTH = $('#myCanvas').width();
HEIGHT = $('#myCanvas').height();
block_x = WIDTH / 2 - 15;
block_y = HEIGHT / 2 - 15;
setInterval('draw()', 25);
}
function clearCanvas() {
context.clearRect(0,0,WIDTH,HEIGHT);
}
function rect(x,y,w,h) {
context.beginPath();
context.rect(x,y,w,h);
context.endPath();
}
function onKeyDown(evt) {
if (evt.keyCode == 39) rightKey = true;
else if (evt.keyCode == 37) leftKey = true;
if (evt.keyCode == 38) upKey = true;
else if (evt.keyCode == 40) downKey = true;
}
function onKeyUp(evt) {
if (evt.keyCode == 39) rightKey = false;
else if (evt.keyCode == 37) leftKey = false;
if (evt.keyCode == 38) upKey = false;
else if (evt.keyCode == 40) downKey = false;
}
function drawGameBottomLine() {
context.beginPath();
context.moveTo(0,530);
context.lineTo(450,530);
context.strokeStyle = 'yellow';
context.stroke();
}
function draw() {
clearCanvas();
if (rightKey)
block_x += 5;
else if (leftKey)
block_x -= 5;
if (upKey)
block_y -= 5;
else if (downKey)
block_y += 5;
if (block_x <= 0)
block_x = 0;
if ((block_x + block_w) >= WIDTH)
block_x = WIDTH - block_w;
if (block_y <= 530)
block_y = 532;
if ((block_y + block_h) >= HEIGHT)
block_y = HEIGHT - block_h;
//all items that have to be redrawn go here.
drawScore();
drawExtraLives();
drawPlayerOne();
drawReady();
//drawCircle();
drawGameBottomLine();
context.drawImage(imageObj, block_x,block_y);
//context.fillRect(block_x,block_y,block_w,block_h);
}
$(document).keydown(onKeyDown);
$(document).keyup(onKeyUp);
init(); //This method sets up the init for the whole game (all things that have to be redraw will be in the draw method.
</script>
</body>
</html>
function drawCircle() {
context.beginPath();
context.arc(anArray[0].x, anArray[0].y, anArray[0].r, 0, Math.PI*2, false);
context.fillStyle = 'yellow';
context.fill();
//context.closePath();
/*
for(var i=0; i<numCircle; i++) {
canvasContext.fillStyle='#123321;'
drawCircle(anArry[0].x,anArry[0].y,anArry[0].r,canvasContext);
}
*/
}