pure-js-challenge/tree.html at master · a97marbr/pure-js-challenge · GitHub

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<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title>Document</title>
	<script>
		const HEIGHT=600;
		const WIDTH=600;

		var canvas;
		var ctx;
		var isRunning=false;


		function setup()
		{
			canvas = document.getElementById('canvas');
			ctx = canvas.getContext('2d');
			ctx.canvas.height=HEIGHT;
			ctx.canvas.width=WIDTH;

			render();
		}

		function render()
		{
				ctx.clearRect(0,0,WIDTH,HEIGHT);
				ctx.translate(WIDTH/2,HEIGHT);

				drawBranch(100,0);

				if(isRunning){
						requestAnimationFrame(render);
				}
		}

		function drawBranch(len, angle)
		{
				ctx.beginPath();
				ctx.moveTo(0,0);
				ctx.rotate(angle);
				ctx.lineTo(0,-len);
				ctx.stroke();
				ctx.translate(0,-len);

				if(len>5){
						var min=Math.PI/12;
						var max=Math.PI/6;
						var random_left = Math.random() * (+max - +min) + +min;
						var random_right = Math.random() * (+max - +min) + +min;

						ctx.save();
						drawBranch(len*0.70, -random_left );
						ctx.restore();
						ctx.save();
						drawBranch(len*0.70, random_right );
						ctx.restore();
				}
		}
	</script>
</head>
<body onload="setup();">
	<body>
		<canvas id="canvas" style="border:2px dotted pink;"></canvas>
	</body>
</body>
</html>