java-visualizations/RandomTrianglesDemo.html at master · grahammitchell/java-visualizations · GitHub

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<!DOCTYPE html>
<html>
<head>
	<meta charset="UTF-8">
	<title>Random Triangles Demo</title>
	<style type='text/css'>
		canvas {
			border: 1px solid black;
		}
	</style>
</head>
<body>
	<canvas id='canvas' width='800' height='600'></canvas>
	<script type='text/javascript'>
		var ctx;

		function draw(ctx) {
			ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height);
			var x1, x2, x3, y1, y2, y3, r, g, b;

			for ( var n = 0; n<500; n++ )
			{
				x1 = Math.floor( Math.random()*ctx.canvas.width );
				x2 = Math.floor( Math.random()*ctx.canvas.width );
				x3 = Math.floor( Math.random()*ctx.canvas.width );
				y1 = Math.floor( Math.random()*ctx.canvas.height );
				y2 = Math.floor( Math.random()*ctx.canvas.height );
				y3 = Math.floor( Math.random()*ctx.canvas.height );
				r = Math.floor( Math.random()*256 );
				g = Math.floor( Math.random()*256 );
				b = Math.floor( Math.random()*256 );

				ctx.fillStyle = "rgb("+r+","+g+","+b+")";
				ctx.beginPath();
				ctx.moveTo(x1, y1);
				ctx.lineTo(x2, y2);
				ctx.lineTo(x3, y3);
				ctx.fill();
			}
		}

		function main() {
			ctx = document.getElementById('canvas').getContext("2d");
			draw(ctx);
		}

		main();
	</script>
</body>
</html>