MCG Modifier Delete Faces by Smoothing Group

[Anonymous]

Hello.

I struggle with creating a MCG modifier that deletes polygons based on smoothing group (deleting all faces with other than selected smoothing group) with maintaing original normals.

Unfortunatelly after many tries I can't manage to make it to work.

Below are some of my test - one dosen't work at all, and other doesn't give expected result.

I don't know how to make some kind of loop or test whole array and then pass that to output without errors.

Thanks in advance

[jon.bell]

Hello,

Thank you for contacting Autodesk Technical Support. My name is Jon and I'm happy to assist you on this issue.

I understand that you're having unexpected results when trying to create an MCG modifier that deletes polygons based on their smoothing groups, and you cannot get this to work properly.

Could you please let me know if you've installed Service Pack 2 for 3ds max 2016? Among other issues, that particular SP addresses a known defect in MCG where all smoothing groups were set to 0 instead of having appropriate smoothing groups set on each face. This issue may be what you're seeing in max, if you don't have the newest service pack installed. (And if you do, then we may want to escalate this issue as a new or related defect.)

If you haven't yet downloaded and installed SP2, you can get it (and other 3ds max downloads) from here:

https://knowledge.autodesk.com/support/3ds-max/downloads

Please let me know if this suggestion helps, and I look forward to hearing from you.

Best regards,

Jon A. Bell

Autodesk Technical Support

[Anonymous]

Thanks for reply.

I've just installed sp2, but I thing that was not the issue.

Anyway - for now I just try to make deleting faces by selection - as first step to final solution, and I still can't get it to work.

Here it is what I got:

Main problem is this filter.

I don't know if it should work when I feed it with IArray[Face3] when it wants IArray[T] - I cant fugure out how to convert it to desired array.

Anyway I thought MeshFaces and FaceSelection Arrays should have exactly the same length.

Still don't sure if I am trying to use Filter node in the right way.

[jon.bell]

Hello,

Thank you for the update on your MCG question. I submitted your inquiry to one of our MCG developers, and he was kind enough to include the following examples and information, below:

"The trick with Smoothing Groups (SG) is that they are accessed via 2 power of their SG.

"There is some documentation about this in the MAXScript docs for more information.

http://help.autodesk.com/view/3DSMAX/2016/ENU/?guid=__files_GUID_58D1F8B6_0012_4727_AA29_B2C79EA46E1...

"I've attached a graph, a screenshot of it, and a 3ds max scene that does what the user is trying to achieve: filter out faces by SG."

Please let me know if the information above and the attached files help you, and thank you for contacting Autodesk.

Best regards,

Jon A. Bell
Autodesk Technical Support

[Anonymous]

Provided files helped a lot - thanks.

I've made a few changes to achieve desired filtering with ignoring one SG.

Below how it works now: (left - original mesh. right - 2 references: top with SG 1 + 31, bottom with SG2 + 31)

And changes in the MCG:

For some reason it doesn't work with 32th group - but it shouldn't be a problem on the long run.

Now the bigest problem is to maintain original normals - I guess now they are generated on the fly, so I need them to be transfered from original mesh to final mesh.

The whole purpose of this approach is to build an organic level made of subchunks which conects each other seamlesly.

I tried to make it with use of script: vertex-normals-stitcher but with my mesh it crashed a lot and worked to slow to fit into my pipeline.

I've made some test trying to pass vertex normals but now I am certain I can't manage them to work.

I would be thankfull to make this final feature to work.

Used files in attachmens

[jon.bell]

Hello,

Thank you for the update on this issue, and I'm glad the files we provided helped you out.

I've flagged this thread for our primary MCG developer and pointed him to your most recent post and question about adjusting your face normals and passing along the vertex information. If I get an update directly from him I'll let you know.

One other place I could suggest for MCG support -- if you're on Facebook, there's a 3ds max MCG Facebook community page that I highly recommend you join. Both our developers and "power users" are on there, and would be happy to help you and see your work. (And currently, this public group has 5,413 members!) You can get more information on it at the link below:

https://www.facebook.com/Autodesk3dsMax/posts/10153399104407246

Thank you again for contacting Autodesk Technical Support, and have a great week.

Best regards,

Jon A. Bell

Autodesk Technical Support

[ads_royje]

Hello,

I have verified, for the 32th smoothing group it does not work because the number is too big for MCG int32.

This is a current limitation for int32 in MCG. 😕

For the vertex normal, they are recomputed by MCG.

MCG recomputed normals for vertex and faces can be queried and used in MCG as vectro3, but cannot be set neither on vertices nor on faces.

We currently do not support edited (via Max's Normal modifer) or editing vertex normal in MCG.

[Anonymous]

Thanks for replies.

Too bad about the normals.

I'll try to find out some solution whit storing normals in VC and then retrieving them via some plugin (hopefulluy I'll find one).

Any chance such support for normals will be provided in 3ds max 2017?

I don see category Scripting / MCG in General Feature Requests but I'll try to squeeze it somewhere.

[ads_royje]

That is great! 🙂

Perfect place for it!

MCG dev team is now aware of this limitation for normals in MCG.

For the time being, it is not planned to be.

Thank you for your feedback!

[Anonymous]

Thanks !

[MattOstgard]

You should be able to tell if the 32nd smoothing group is active by checking if the smoothing group value is negative or positive. If it is negative then the 32nd group is active. Also please ask the dev team to implement a bit.get() node (and other bitwise operations) for MCG. Thanks.

Edit: I should also say I found this thread trying to make a modifier that edits normals as well. A "Set Normal" node would be great to have.

Also here is Gomo's feature request for anyone else that finds this and wants to vote it up: http://3dsmaxfeedback.autodesk.com/forums/80695-general-feature-requests/suggestions/11592324-mcg-su...

[Anonymous]

Thanks for suggestion.

Right now 31 smoothing groups will be enough, I thought that if I need more I would try to implement an use of combination of two smoothing groups (like delete / spare polys only if they have two given smoothing groups).

About "bit.get() node" you would have to elaborate - because right now I'm not sure where exactly you want me to ask this - they read this forum, and I don't think I know exactly what to tell - my overall knowledge of maxscript is not so good.

Sorry.