第一种方法：桃心形公式


代码实现的一种方法

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>使用桃心形方程绘制爱心</title>
</head>
<body>
    <canvas></canvas>
    <script>
        var canvas = document.querySelector(\'canvas\');
        var ctx = canvas.getContext(\'2d\');
        canvas.width = window.innerWidth;
        canvas.height = window.innerHeight;
        var Heart = function(ctx, x, y, a) {
            this.ctx = ctx;
            this.x = x;
            this.y = y;
            this.a = a;
            this.vertices = [];
            for(let i=0; i<50; i++) {
                var step = i/50*(Math.PI*2);//设置心上面两点之间的角度，具体分成多少份，好像需要去试。
                var vector = {
                    x : this.a*(16 * Math.pow(Math.sin(step), 3)),
                    y : this.a*(13 * Math.cos(step) - 5 * Math.cos(2 * step) - 2 * Math.cos(3 * step) - Math.cos(4 * step))
                }
                this.vertices.push(vector);
            }
        }
        Heart.prototype.draw = function() {
            this.ctx.beginPath();
            this.ctx.translate(this.x,this.y);
            this.ctx.rotate(Math.PI);
            for(let i=0; i<50; i++) {
                var vector = this.vertices[i];
                this.ctx.lineTo(vector.x, vector.y);
            }
            this.ctx.fillStyle = "red";
            this.ctx.fill();
        }
        canvas.onmousedown = function(e) {
            var x = e.offsetX;
            var y = e.offsetY;
            var a = 6;
            var heart = new Heart(ctx, x, y, a);
            heart.draw();
        }
    </script>
</body>
</html>

第二种方法：笛卡尔的心形线


代码实现的一种方法：

<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>使用笛卡尔心形线方程绘制爱心</title>
</head>
<body>
	<canvas></canvas>
	<script>
		var canvas = document.querySelector(\'canvas\');
		var ctx = canvas.getContext(\'2d\');
		canvas.width = window.innerWidth;
		canvas.height = window.innerHeight;
		function Heart(ctx, x, y, a) {
			this.ctx = ctx;
			this.x = x;
			this.y = y;
			this.a = a;
			this.draw = function() {
				this.ctx.beginPath();
				this.ctx.translate(this.x, this.y);
				this.ctx.rotate(Math.PI);
				var start = 0;
				for(var i=0; i<500; i++) {
					start += Math.PI*2/500;
					var end = start+Math.PI*2/500;
					var r = this.a*(1-Math.sin(start));
					ctx.arc(0, 0, r, start, end, false);
				}
				ctx.fillStyle = "red";
				ctx.fill();
			}
		}
		canvas.onmousedown = function(e) {
			var x = e.offsetX;
			var y = e.offsetY;
			var a = 60;
			var heart = new Heart(ctx, x, y, a);
			heart.draw();
		}
	</script>
</body>
</html>

第三种方法：

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本文链接：https://www.cnblogs.com/sunshine21/p/7757958.html