A Menger sponge with raytracing. In the sponge-center is a light source. The image illustrates the functionality of raytracing by computers and the resultating shadow position and orientation. The bottom touches on the Menger sponge. The main light source is on the left over the bottom so that the shadow is behind (right to the Menger sponge) the IFS fractal.
<a href="//commons.wikimedia.org/wiki/User:PantheraLeo1359531" title="User:PantheraLeo1359531">PantheraLeo1359531</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>