random by id

[mayanic]

Hey,

very happy about the recent upgrade - thanks very much!!!

i was searching for a way to randomize the color of my leaves / grass etc.
cause of performance reasons we combine the geometry and loose our object IDs?!

how to utilize random by id?!
and - not helpful in this case because most of our leaves grass patches have more than one face - but does "randombyid" work with face ids?

hope to hear from you soon

thx

[Algehov]

As I mentioned in the previous thread about randomByID (which is btw really great, and probably my most used new feature since it was added/opened for use!).
I would also like to have something that does what mayanic mentioned. I suggested a randomByShell (sort of like elements in 3ds max I guess). But I assume those dont come with a unique IDs like objects does, so its abit harder to "just" implement.
But maya (and most other 3d programs I guess) doesnt like a ton of transform nodes, so we too combine all the leaves etc for eatch tree. Being able to randomize textures and colors based on geometry shell, just like object IDs would be really kick ass!

[mayanic]

yep, also my favorite one

randomize by shell would be the solution ^^

[mayanic]

uv-shells or even better poly-shells (connected faces) would be nice

[Algehov]

Yep, poly shells is what im refering to. But another one for uv shells would in some cases also be pretty nice.
But I definitely prefer poly shells

[ivaylo.ivanov]

Detecting uv/poly-shells at render time will present an overhead. More viable approach is to use face IDs, but Maya doesn't have this either. Another approach that may work is creating a color set from the uv/poly-shells in Maya. Not sure if a 3rd party plugin must be used though. This method will break the subdivision, so it's a bit limited.

[vlado]

Well, Vlado Nedev already coded it for V-Ray for Modo, so it's just a matter of making use of it...

Best regards,
Vlado

[Algehov]

Did he code the ID on poly-shells part? Or the color sets on poly shells part? Either way, making use of it would be great!
Its a shame if there's no good way of doing on poly-shells as it would have been amazingly usefull! The color set method sounds smart however, but quite a hassle to do manually of course. And not working with subdivisions is a bit limiting yea. But a pretty good workaround none the less.

[vladimir.nedev]

Did he code the ID on poly-shells part? Or the color sets on poly shells part? Either way, making use of it would be great!
Its a shame if there's no good way of doing on poly-shells as it would have been amazingly usefull! The color set method sounds smart however, but quite a hassle to do manually of course. And not working with subdivisions is a bit limiting yea. But a pretty good workaround none the less.

I will try to add it for tomorrow's nightly build.
It works on polygon shells. Like Ivaylo said, it does add some time and memory overhead, but only if you use it. It uses up to 8 bytes per mesh triangle.
Limitations are:
- doesn't work in RT GPU
- doesn't work with V-Ray Proxies. For them we need to bake this information in the .vrmesh file itself, when it is created (as a color set or a special uv map). This is because the mesh get splits into voxels in the .vrmesh file, so the connectivity information is lost.

Greetings,
Vladimir Nedev

[Algehov]

That would be really cool and nice of you!
Is it something that would continue to not work on proxies, or can something be done about that in the future? What about an .abc file instead of a an vrmesh?
Will it for that same reason not work on XGen archives then too?

Thanks a lot!

[vladimir.nedev]

So, the Random by Polygon Shell output of the Sampler node will be in the nightly build from 2016.03.08.
Here is an example, where it is used to drive a ramp texture :



Each leaf consists of a number of polygons, and is completely disconnected from the branches of the tree.

Is it something that would continue to not work on proxies, or can something be done about that in the future?

We will try to fix it, but like I said, it may require adding additional information to the .vrmesh files when they are being created.
It's been requested for V-Ray for MODO as well.

What about an .abc file instead of a an vrmesh? Will it for that same reason not work on XGen archives then too?

It won't work on .abc files either, as internally they go through the same interface as .vrmesh files. Although, for .abc files the polygon connection information is there, so it can be done.
I am no sure about XGen, but if it is indeed using V-Ray Proxies internally to load the .abc files, then it won't work.

At least, it's a start.

Greetings,
Vladimir Nedev

[Algehov]

Thats great! Thanks a ton.
Looks really good, and cant wait to try it out.
I can give it a try on a XGen archive when the nightly comes up.

Keep us updated about when it might be working correctly in proxies, as thats when it starts to get really powerful after all
Thanks again

[pechart]

Awesome, thanks a lot!

[Komposer]

I hoped to find the "Random by Shell" in the actual nightlys
(...Maya2015..Win7...Vray3.3.002 from yesterday...)

[ivaylo.ivanov]

You will need 3.35 nightlies.