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Reimport breaking either mapping or material assignment, checkbox texture won't go away

Development Discussion Datasmith
#1

Hi Everyone
I’m having an issue where after I click and re import in Unreal after doing an updated Datasmith export, some meshes are breaking, they remain with a check box texture assigned even through there is a material for it. I open and save the material and it might recompile, but the checker box remains, I have to delete the entire datasmith file in unreal and then re export and then bring it in again
Any reason this might be happening?

#2

You need to report your version of Datasmith/Engine when stating issues. Hard to help without that.

#3

Thanks for the pointer Ken.
it’s 4.20.3 engine and the 4.20 Datasmith Max exporter.
Max version is 2016.
I’m a lot of issues and will add scene shots on Monday.
It’s using groups, something new I’m trying. Are Max groups compatible with Datasmith?
I’m also having the checkers show up when trying trying to assign a different material than the one made by Datasmith

#4

Groups in Max are translating to Unreal as Null objects parents to the nodes inside the group.

#5

What would cause a mesh not to be able to display it’s material or any material (One exported from datasmith along with that mesh) or turn checker board when another material is applied?
I’ve had to resort to destroying the datasmith exports and redoing them.

#6

Generally speaking the “defaut” or “none” material in Unreal looks like a grey checker board material. This is used to represent at least two conditions:

  1. A mesh that has no material applied from the incoming model (ex: make an object in max, don’t apply material, import → you’ll see the pattern)

  2. A temporary display while Unreal waits for the real material to compile on the graphic card. In that case, if this persists this is usually because one material applied on the object has compile errors, invalid connection etc.

Its difficult to help you more without precise information about your model, the steps you are doing in max prior to reimport etc. Since 4.21 has been shipping I would start by trying out the same workflow in that release. If it persists, i’d log a support ticket and provide all the data (archived max model, some screenshots documenting the issue etc)

#7

Thanks Pierre, my guess it’s a bad import, re importing seems to fix it, delete the old, redo the datasmith export and it seems to work after that.

Loses a bit of setup time but seems to work after with fewer issues. I’ll see if we can update ad if that improves things.