Tessellation multiplier error. "Error [SM5] error X3000: unrecognized identifier 'FVertexFactoryInterpolantsVSToDS'"

Hello!

I am getting the following error inside my UE 4.10 project when trying to compile a material with tessellation mode set to “Flat Tessellation” or “PN Triangles”.

Error [SM5] error X3000: unrecognized identifier ‘FVertexFactoryInterpolantsVSToDS’

This error only happens in one specific project that I have been working on but not in a brand new test project. Any ideas of what I could do to fix this?

Thank you!

Hi Timetravel,

Are you able to provide a sample project that can reproduce this? If it’s not happening in a new project I don’t think I’ll be able to reproduce on my end, and I’ve not seen anything stand out when I’ve created tessellated materials lately.

If you’re able to provide a sample project, strip out anything that is not needed to see the issue to keep file size down.

If not, you may want to try clearing the Saved and Intermediate folders fromy our project folder. This will generate new files for these folders and hopefully resolve any issue that you’re can’t reproduce in a new project.

Hi !

Thank you for your answer. After doing some more testing on a blank new project I have come to the conclusion that this error shows up when you set a material to either PN Triangles or Flat Tessellation then add a Tessellation multiplier and then apply this material to an emitter in a particle system. Interestingly even after you delete the entire particle system from your project the error still remains.

Thanks for the more informative repro steps! That helped me narrow down what’s happening.

It’s not really a bug, but it’s something that could probably be handled better in the long term.

Anytime a material is assigned to an actor, like a Skeletal Mesh, Static Mesh, Particle System, etc it needs to recompile to be handled with these types of actors. This places a checkbox next to the Usage type in the Details panel of the material node. So anytime the material is recompiled to handled these other types of assets it will place a checkbox there, but if you decide it’s not needed any longer it will not remove the check box, in other words, it doesn’t automatically unset them. You will need to manually uncheck Particle System, in your case, and save the material to get rid of the warning.

have the same problem and unchecking indeed let you get rid of the warning and use the material again, but i do want to be able to use tessellation on a particle system so what should i do?

Ran into this problem. Unchecking the box works. Maybe have a warning when throwing a mat into particle system. Of course, might be pointless with Niagra replacing cascade.

Finally fixed it!
Just go to your

  1. Decal material details
  2. Uncheck the box “Used with Niagara sprites” if it is checked.
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