For anyone wondering what distance fields are for, check out: http://iquilezles.org/www/articles/raymarchingdf/raymarching... The code to generate all those images comes to only 13k.

There's a simple tutorial for modelling with distance fields on the same site: http://iquilezles.org/www/articles/distfunctions/distfunctio...

If you're into this kind of thing it's worth exploring that site.

Did anything change that made this possible that it wasn't possible before? Was it just that we have faster computers now? Or something else?

Signed distance fields have been used in VFX since the mid-1990s. One of the first paper formalizing its editing techniques was by Ken Museth in 2002:

http://diyhpl.us/~bryan/papers2/frey/applications/Museth%20K...

My contribution to the field (in collaboration with Ken, the author of the above) is making these scalar volumetric representations more scalable via using a recursive hierarchical sparse representation:

https://www.cs.ubc.ca/nest/imager/tr/2006/Batty_HRLE/

Ken Museth is now the head of R&D at Dreamworks Animation and picked up a Sci Tech Oscar two years for his level set work:

https://www.youtube.com/watch?v=5FwOc4OSOR0

Pretty nice. Is there any way to see/edit the tree of previously "applied" primitives?

I really like the SDF visualization in this tutorial: https://youtu.be/s8nFqwOho-s?t=12m

Very nice ! I think it would be great to have the max iterations as an option as well ;)