gaspargergo.github.io/square2.html at master · gaspargergo/gaspargergo.github.io · GitHub

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<!doctype HTML>
<html>

<head>
	<style type="text/css">
		#canvas{
			position: absolute;
			left: 50%;
			margin-left: -300px;
			top: 50%;
			margin-top: -300px;
		}
	</style>
</head>

<body>

	<canvas id="canvas" height="600px" width="600px"></canvas>

	<script>
		var c = document.getElementById("canvas");
		var ctx = c.getContext("2d");

		ctx.fillRect(0,0,c.width,c.height);

		var triangleSize = 0;
		var triangleStyle = 0;
		var start = 600;
		ctx.fillStyle = '#'+ Math.random().toString(16).slice(-6);

		triangleFill();

		function triangleFill(){
			requestAnimationFrame(triangleFill);

			drawTriangle(start,start, triangleSize,triangleStyle);
			triangleSize += 15;

			if(triangleSize > c.width*2){
				ctx.fillStyle = '#'+ Math.random().toString(16).slice(-6);
				triangleSize = 0;
				if(triangleStyle == 0){
					triangleStyle = 1;
					start = 0;
				}
				else{
					triangleStyle = 0;
					start = 600;
				}
			}
		}

		function drawTriangle(x,y, size, type){
			ctx.beginPath();
			ctx.moveTo(x,y);
			switch(type){
				case 0: // up
					ctx.lineTo(x,y-size);
					ctx.lineTo(x-size, y);
					ctx.lineTo(x,y);
					break;
				case 1: // down
					ctx.lineTo(x+size,y);
					ctx.lineTo(x,y+size);
					ctx.lineTo(x,y);
					break;
			}
			ctx.fill();
		}
	</script>
</body>

</html>