Just guessing: inverted normals

I built a simple closed shape, a kind of up-down stroke on top, and a convex bottom, then extruded it. the result is a sort of cylinder with concave dent on the side. I’m not sure yet, having not imported it into blender, but in Codea, the faces in the indented part don’t appear. I suspect they are present but their normals are inverted (because that part is concave?).

If this is a known thing, please comment. If not, I can explore further or provide pictures or whatever would help.


This might be a known issue, but we might prioritize it so it won’t occur in the future. Can you please send the .UMK file to “[email protected]” and we will take a look to understand if it is the same bug we’re ware of.


will do, next time i’m on the iPad.

Thank you!

I believe I am having the same issue. I installed uMake recently and have been testing basic features and integration with other softwares I use.

I ran into an issue with exporting the file to OBJ (or STL) and then trying to import it into Twinmotion 2019. Turns out the faces for a simple cube I made appear and disappear depending on which angle they are viewed from. I would expect all inner surfaces to be invisible and all outer surfaces to be visible, but it’s a mix of all that, never rending the whole cube at once (I made a video but cannot upload it here it seems).

I made the cube first drawing 4 sides with auto-surfacing, then using the pull feature.

It looked promising but I haven’t been able to play with uMake that much as this is likely a dealbreaker for me.

Note: I also have issues with the scale. I’m not sure which format to pick for the export but I end up with tiny cubes I have to manually size up (or guess the unit scaling number at import time). Twinmotion seems to only import .obj or .stl among the formats uMake has. Here I made the cube in meters and have to size it up by a factor of 100. I have zero issues importing my Sketchup projects. Works out of the box.

Hi @Nic,

Thank you for the feedback.

You’re right. We’re aware of the inverted surfaces issue and have a solution for it. We will do our best to solve it sooner than later.

Thank you for your patience.

As for the scale issue - I’m not sure why the exported OBJ/STL scale would change but we will look into it.


Thanks @evi, happy to hear a fix is in the works. Any ETA on that? My free trial will soon expire and I’m not sure I want to commit to uMake just yet. I also worry about investing time in complex models only to have to remake them again after the fix (assuming the issue happens at modeling time rather than export time). Would existing models be fixed as well (issue during the export), or just future models (issue during modeling)? Thanks!

The scaling thing is annoying but I can work around it somewhat for now. I really wish I didn’t have to [perhaps incorrectly] guess scaling factors though. Not a dealbreaker as long as this is temporary (and / or I understand what I am doing wrong).

Note: I have another issue, which I hope is fixed as well. Draw a square with auto-surfacing, pull up a bit, offset the top side inward (to make the outline of the inner side of a wall on a base foundation), then pull the wall portion up (between the outer edges and the offset)… the base foundation loses a surface which is neither being pulled nor deleted (I wouldn’t expect it to be altered in any way). This essentially forces me to draw the walls up rather than simply pull.

Let me know if I should make separate posts for each issue, I realize I may be hijacking this thread here.


Thanks, @Nic - hope you had a great weekend!

As for the normals issue - the fix won’t be ready in the next 14 days as it requires thorough testing on our end before we release it to the public. I understand if this is a deal-breaker for you, and we’re doing our best to solve this issue. Once the fix is ready, it will only apply to newly created surfaces. There won’t be support for surfaces created using the older method.

Scaling issue - I’m trying to reproduce it but without success. Would you mind attaching the UMK file you’re trying to export?

Push & Pull bug - thanks for the heads up! We will look into it and include a fix in our next update.


Hi @evi, thanks for the reply.

I’d be happy to include the UMK file but, as a new user I am not allowed to upload files. Not sure if you can change that.

I can also export one for the pull issue.

@Nic, Please send them to “[email protected]” and I’ll take it from there.

Hi @Nic,

Thanks for sending the files.

Here are my comments:

  1. Push & Pull issue - we’re aware of this bug now and will solve it in our next updates.

  2. Scale - I imported an OBJ export of the file you sent and then imported it into Rhino. Seems like the dimensions/scale are similar to the ones in uMake.

Here are the screenshots from Rhino and uMake:

Maybe the software you’re using is changing the scale for some reason?


i created a new object, exported to .obj and some faces have inverted normals, as does the cylinder that’s its base, created by making a circle and pulling it out. Is this the same bug from six months ago? wasn’t that fixed?

@RonJeffries, sorry for the delay! Yes, you’re right, it might be a bug in our export process. We will look into it based on the file you sent us. Thank you for sending it.

Thanks and stay healthy,

Hi! I’m having problems with inverted normals for OBJ and STL files too :frowning: Do you know when this will be fixed? I started a 14 day trial today and I love the process of creating with uMake, but unfortunately whenever I export files as an OBJ or STL, certain faces look hollow or disappeared, just like other users have reported in these forums. It’s such a shame, because otherwise I could see this being a wonderful tool for creating 3D assets for video games, but the hollow faces make it unworkable. Are there any workarounds I could try in the meantime to create better files in the app? What if I exported as another file format and then converted it to obj or stl elsewhere? I’m looking for a way to do that. Does everyone using uMake have this same exporting problem or only some people? Thanks!

Hi @Claire,

Thank you for your feedback. I just sent you an email.

We’re aware of this issue, and we will prioritize the solution for this very soon. We’re sorry for the inconvenience.

In the meantime, my recommendation would be to export the creation to IGES/STEP file and open it in another 3D modeling software and from there export it to STL/OBJ.

We’re doing our best to solve this issue as soon as possible. Thank you for your patience.


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Thanks! Looking forward to the solution :blush:

Is there any progress on this, please?
I have just subscribed to uMake and now need to export some very simple models to use in other applications but I am seeing the same inverted normals issue (or I seem to be).
The model looks fine in uMake but exporting to obj format leaves all sorts of faces that are not rendering. For example, take the new lego model tutorial and try and export it - you will get gaps on the ‘lego’ bricks.

Hi @megapode,

Modifying surfaces normals configuration is still in our roadmap and we hope to get to it sooner than later maybe by the end of this year. In the meantime, you can try to switch to a “double sides surfaces” / “two-sided surfaces” mode in the other software you’re using - this why you would be able to see the model as it shows in uMake. (It depends if the other software has this kind of option of course).