DmitrySoshnikov/sierpinski-triangle.html

## sierpinski-triangle.html
<!DOCTYPE html>
<html>
  <head>
    <title>Sierpiński triangle</title>
  </head>
  <body>
    <canvas id="area" width="600" height="600"></canvas>
    <script type="text/javascript">

      // Sierpiński_triangle:
      //
      // Is a fractal and attractive fixed set with the overall shape
      // of an equilateral triangle, subdivided recursively into smaller
      // equilateral triangles.
      //
      // Details: https://en.wikipedia.org/wiki/Sierpiński_triangle
      //
      // by Dmitry Soshnikov <dmitry.soshnikov@gmail.com>
      // MIT Style License, 2019


      const canvas = document.getElementById('area');
      const ctx = canvas.getContext('2d');

      // Main triangle.
      const T = [[299, 0], [0, 599], [599, 599]];

      // Start point.
      let current = [299, 299];

      function midPoint([x1, y1], [x2, y2]) {
        return [(x1 + x2) / 2, (y1 + y2) / 2];
      }

      function putPixel(x, y, color) {
        ctx.fillStyle = color;
        ctx.fillRect(x, y, 1, 1);
      }

      function randomInRange(min, max) {
        return Math.floor(Math.random() * (max - min + 1)) + min;
      }

      function randomColor() {
        return '#' + Math.floor(Math.random() * 0xffffff).toString(16);
      }

      // Max steps.
      const maxSteps = 500000;

      function step(color) {
        const to = randomInRange(0, 2);
        current = midPoint(current, T[to]);
        putPixel(...current, color);
      }

      function run() {
        const color = randomColor();
        ctx.clearRect(0, 0, 600, 600);
        for (let i = 0; i < maxSteps; i++) {
          step(color);
        }
      }

      // Setup main triangle.
      putPixel(...T[0], '#f00');
      putPixel(...T[1], '#0f0');
      putPixel(...T[2], '#00f');

      // Go.
      run();

      // Refresh every second.
      setInterval(run, 1000);
    </script>
  </body>
</html>
	<!DOCTYPE html>
	<html>
	<head>
	<title>Sierpiński triangle</title>
	</head>
	<body>
	<canvas id="area" width="600" height="600"></canvas>
	<script type="text/javascript">

	// Sierpiński_triangle:
	//
	// Is a fractal and attractive fixed set with the overall shape
	// of an equilateral triangle, subdivided recursively into smaller
	// equilateral triangles.
	//
	// Details: https://en.wikipedia.org/wiki/Sierpiński_triangle
	//
	// by Dmitry Soshnikov <dmitry.soshnikov@gmail.com>
	// MIT Style License, 2019


	const canvas = document.getElementById('area');
	const ctx = canvas.getContext('2d');

	// Main triangle.
	const T = [[299, 0], [0, 599], [599, 599]];

	// Start point.
	let current = [299, 299];

	function midPoint([x1, y1], [x2, y2]) {
	return [(x1 + x2) / 2, (y1 + y2) / 2];
	}

	function putPixel(x, y, color) {
	ctx.fillStyle = color;
	ctx.fillRect(x, y, 1, 1);
	}

	function randomInRange(min, max) {
	return Math.floor(Math.random() * (max - min + 1)) + min;
	}

	function randomColor() {
	return '#' + Math.floor(Math.random() * 0xffffff).toString(16);
	}

	// Max steps.
	const maxSteps = 500000;

	function step(color) {
	const to = randomInRange(0, 2);
	current = midPoint(current, T[to]);
	putPixel(...current, color);
	}

	function run() {
	const color = randomColor();
	ctx.clearRect(0, 0, 600, 600);
	for (let i = 0; i < maxSteps; i++) {
	step(color);
	}
	}

	// Setup main triangle.
	putPixel(...T[0], '#f00');
	putPixel(...T[1], '#0f0');
	putPixel(...T[2], '#00f');

	// Go.
	run();

	// Refresh every second.
	setInterval(run, 1000);
	</script>
	</body>
	</html>