black-hole.js
Demo and explanatory blog post.
In the time-honored tradition of taking yet another noun and making .js file out of it, I proudly present black-hole.js, which uses a numerical ordinary differential equation solver from numeric.js, and some nice WebGL utilities from glfx.js, to render the gravitational lensing of a black hole.
Note: due to HTML5's security restrictions, you must either render images from your own domain or from a server where CORS is ok.
Usage:
<div id="canvas_placeholder"></div>
<script src="https://code.jquery.com/jquery-1.11.2.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/numeric/1.2.6/numeric.js"></script>
<script src="./black-hole.min.js"></script>
<script>
var corsOkImageUrl = 'https://s3-us-west-1.amazonaws.com/cliffcrosland-public/black_hole_js/milky_way.jpg';
BlackHole.blackHoleifyImage('canvas_placeholder', corsOkImageUrl)
</script>You can also specify some parameters to change the gravitational lensing effect:
<script>
BlackHole.blackHoleifyImage(placeholderId, corsOkImageUrl, {
distanceFromBlackHole: 70, // 80 is default
polynomialDegree: 3, // 2 is default
numAngleTableEntries: 2000, // 1000 is default. More might improve quality but impact performance
fovAngleInDegrees: 60, // 73 is default. Yeah, it's an unusual choice, but it just looked cool, ok?
});
</script>