flappybird原理解析 JQuery版本

時間 2019-11-25

原文原文鏈接

難度解析一、動畫效果 requestAnimationFrame 二、碰撞檢測 DIV以前是否重合css

<html>
  <head>
    <meta charset="utf-8" />
    <style>
body{overflow-x:hidden;}
.ground{position:absolute;top:300px;width:10000px;height:10px;background:url(./ground.png) repeat-x}
.tree{width:100px;height:100px;background:green;position:absolute;left:1000px;top:200px;
}
</style>
    <title></title>
  </head>
  <body>
  <button onclick="stop();">stop</button> 
  <button onclick="jump();">jump</button> 
  <img src="./bird.png" id="bird" style="position:absolute;top:30px;left:200;border:1px red solid;" />
  <div class="tree" id="tree"></div>
  <div class="ground" id="ground"></div>
 

</body>
 
</html>
<script src="./jquery-1.11.0.min.js"></script> 
<script src="./flppybird.js"></script>

var timer = requestAnimationFrame(fly)
	var x = 0; //場景移動

//主函數
function fly() {
	x--;
	var top = $("#bird").offset().top;
	top += 1;
	$("#bird").css({
		"top": top
	});

	$("#ground").css({
		"left": x
	});
	var treeleft = $("#tree").offset().left;
	treeleft--;
	$("#tree").css({
		"left": treeleft
	});

	//碰撞檢測
	if (checkCollection($("#bird"), $("#tree"))) {
		stop();
		alert("hit!");
	} else {
		timer = requestAnimationFrame(fly);

	}

}

//檢查是否碰撞
function checkCollection(bird, tree) {
	var birdPosition = [];
	birdPosition[0] = bird.offset().left;
	birdPosition[1] = bird.offset().top + bird.height();
	birdPosition[2] = bird.offset().left + bird.width();
	birdPosition[3] = bird.offset().top + bird.height();

	var treePosition = [];
	treePosition[0] = tree.offset().left;
	treePosition[1] = tree.offset().top;
	treePosition[2] = tree.offset().left + tree.width();
	treePosition[3] = tree.offset().top;

	if (birdPosition[2] > treePosition[0] && birdPosition[0] < treePosition[2]) {

		if (birdPosition[1] > treePosition[1]) {
			return true;

		}
	}
	return false;
}

//飛起來
function jump() {
	var top = $("#bird").offset().top;
	top -= 20;
	$("#bird").css({
		"top": top
	});
}

//中止遊戲
function stop() {
	cancelAnimationFrame(timer);
}

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