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我正在嘗試沿着x軸移動圓弧,但它給出的錯誤是x未在更新函數中定義。變量未正確放置或缺少一些參考?無法使用JS在畫布中移動圓弧
代碼
<canvas id="myCanvas"></canvas>
<script>
var myCanvas = document.getElementById("myCanvas");
var c = myCanvas.getContext("2d");
var redArc = new Circle(50, 60, 10, "red");
var greenArc = new Circle(80, 60, 15, "green");
var blueArc = new Circle(120, 60, 20, "blue");
function Circle(x, y, radius, color) {
this.x = x;
this.y = y;
this.radius = radius;
this.color = color;
this.draw = function() {
c.beginPath();
c.arc(this.x, this.y, this.radius, 0, Math.PI * 2);
c.fillStyle = this.color;
c.fill();
}
this.update = function() {
redArc.x += 1;
greenArc.x += 1;
blueArc.x += 1;
this.draw();
}
this.update();
}
function animate() {
requestAnimationFrame(animate);
c.clearRect(0, 0, myCanvas.clientWidth, myCanvas.clientHeight);
redArc.update();
greenArc.update();
blueArc.update();
}
animate();
如何去修復它?任何建議 謝謝!
好了..謝謝..這工作,但涉及的變量和this.x是不是一回事?如果我在this.x或者變量x的位置上設置增量,它是否會產生影響? – tankit88
創建它之前不能使用對象。 – flamelite