Greetings!

I have a little problem with interior surface color after voronoi fracture - it's black. This is what i did not understand:

I've been following tutorial about fractures, and it's about smashing pighead test geo. Here's a simple walkthrough:

1. Geometry - pighead, with shader
2. isoofset - to get scatter points for voronoi inside the geo
3. scatter node
4. voronoi node

So, in doing so and with everything set to default (beside scatter points count), i get interior surface black (example in attachments).

However, recently i found another scene file for the exact tutorial (on this forum for another unrelated to this question issue). As i understand it was made in a previous Houdini version (mine is the latest to date, 17.5.391), and some parameters in nodes are different (it's cool that Houdini is able to load those ‘obsolete’ versions of same nodes with their parameters). When i copy those old nodes from there into my scene, i am able to get white surface color. By trial and error i was able to figure that this issue is due to some changes in Voronoi fracture node.

I have 2 questions:
1.What is that black color? Is it some missing shader (and if so, why is there no issues with old Voronoi fracture node?)
2.How can i achieve white color without using old node from old scene file?

I attached scene file with hopes that someone will be able to see it with the same result as i am.

Thanks in advance!

ps. I thought possibly this was due to a bug, so i updated Houdini to it's latest version, no effect.

Update: with the help from Reddit i was able to resolve the issue by manually coloring the ‘inside’ group of Voronoi fracture.
As for why this is happened - i am relatively new to Houdini, but i reckon this is not an unusual thing when with the new version comes some changes that could broke/severely change the workflow.

I have the same problem. Would you mind sharing the link to Reddit's answer? Or point where should I add the color node inside the group of Voronoi fracture? I'm new at Houdini and unfortunately because of major changes from version to version its hard to follow tutorials. I keep spending more time figuring out there are the settings and nodes located rather than learning how to simulate and render.

maciekstepnik
I have the same problem. Would you mind sharing the link to Reddit's answer? Or point where should I add the color node inside the group of Voronoi fracture? I'm new at Houdini and unfortunately because of major changes from version to version its hard to follow tutorials. I keep spending more time figuring out there are the settings and nodes located rather than learning how to simulate and render.

Gladly, here's the link to my Reddit post: https://www.reddit.com/r/Houdini/comments/dge3pq/voronoi_interior_surface_color/ [www.reddit.com]

Also i'll attach a .hip file for you to dissect.

Basically what was the issue - by default for some reason after Voronoi the material for inside surfaces is the same material used for pig's eyes (or body, which as well not suitable). You can check that in Geometry Spreadsheet on Voronoi node under ‘shop_materialpath’. So i ended up with attribute wrangle node with filter applied to affect only primitives in ‘inside’ group (Voronoi creates 2 groups: inside and outside). In there i just replaced ‘shop_materialpath’. As far as i understand you can just erase it altogether, if you are planning on using Color node after.
I added whitepaint material and used it:

And after that you can use color node for group ‘inside’. That's it.

I hope it doesn't sound too complicated, took me some time to grasp what's what, but i'm glad i am able to share it with someone who is learning Houdini as well (wow, i'm helpful!)

Also i think spending time on figuring how to overcome Houdini stubbornness is very useful