如何阻止我的拖尾线导致对象因数组大小而变慢
随着数组变大，我在画布上的方形对象会急剧变慢。该数组用于存储先前的 x,y 位置，然后拖尾线使用这些位置来绘制自身。
有没有办法让我的对象以相同的速度移动，同时保持整个拖尾线，即我不希望拖尾线在任何时间点消失/消失。
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0"/>
<style>
canvas {
border:1px solid #d3d3d3;
background-color: #f1f1f1;
}
</style>
</head>
<body onload="startGame()">
<script>
var myGamePiece;
var myArrayX = [];
var myArrayY = [];
function startGame() {
myGamePiece = new component(30, 30, "red", 10, 120);
myGameArea.start();
}
var myGameArea = {
canvas : document.createElement("canvas"),
start : function() {
this.canvas.width = 480;
this.canvas.height = 270;
this.context = this.canvas.getContext("2d");
document.body.insertBefore(this.canvas, document.body.childNodes[0]);
this.interval = setInterval(updateGameArea, 20);
},
clear : function() {
this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
}
}
function component(width, height, color, x, y) {
this.width = width;
this.height = height;
this.speedX = 0;
this.speedY = 0;
this.x = x;
this.y = y;
this.update = function() {
ctx = myGameArea.context;
ctx.fillStyle = color;
ctx.fillRect(this.x, this.y, this.width, this.height);
// testing:
ctx.beginPath();
ctx.strokeStyle = "red";
ctx.setLineDash([5,5]);
ctx.moveTo(10, 120);
var arrLength = myArrayX.length;
for(var i=0; i<arrLength;i+=1){
ctx.lineTo(myArrayX[i], myArrayY[i]);
ctx.stroke();
}
}
this.newPos = function() {
this.x += this.speedX;
this.y += this.speedY;
myArrayX.push(this.x);
myArrayY.push(this.y);
}
//end test
}
function updateGameArea() {
myGameArea.clear();
myGamePiece.newPos();
myGamePiece.update();
document.getElementById("test").innerHTML = "size of array: " + (myArrayX.length -1).toString()
}
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相关分类
JavaScript