放多个组件
var redGamePiece, blueGamePiece, yellowGamePiece;
function startGame() {
redGamePiece = new component(75, 75, "red", 10, 10);
yellowGamePiece = new component(75, 75, "yellow", 50, 60);
blueGamePiece = new component(75, 75, "blue", 10, 110);
myGameArea.start();
}
function updateGameArea() {
myGameArea.clear();
redGamePiece.update();
yellowGamePiece.update();
blueGamePiece.update();
}
。。。
移动组件
三个组件在不同方向运动:
function updateGameArea() {
myGameArea.clear();
redGamePiece.x += 1;
yellowGamePiece.x += 1;
yellowGamePiece.y += 1;
blueGamePiece.x += 1;
blueGamePiece.y -= 1;
redGamePiece.update();
yellowGamePiece.update();
blueGamePiece.update();
}
通过在每次更新中更改每个组件的x坐标和y坐标来移动三个组件。
完整代码：
<!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 redGamePiece, blueGamePiece, yellowGamePiece;
function startGame() {
redGamePiece = new component(75, 75, "red", 10, 10);
yellowGamePiece = new component(75, 75, "yellow", 50, 60);
blueGamePiece = new component(75, 75, "blue", 10, 220);
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.x = x;
this.y = y;
this.update = function(){
ctx = myGameArea.context;
ctx.fillStyle = color;
ctx.fillRect(this.x, this.y, this.width, this.height);
}
}
function updateGameArea() {
myGameArea.clear();
redGamePiece.x += 1;
yellowGamePiece.x += 1;
yellowGamePiece.y += 1;
blueGamePiece.x += 1;
blueGamePiece.y -= 1;
redGamePiece.update();
yellowGamePiece.update();
blueGamePiece.update();
}
</script>
<p>通过在每次更新中更改x坐标和y坐标来移动三个组件。</p>
</body>
</html>
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