Unreal Engine 4 tripling vertice count? [Blender to Unreal] [Noob Question]

Hello! I am a beginner when it comes to unreal and blender and everything when it comes to it, and I was just wandering about the vertice count…
I have made this model of the mesoamerican temples, which, according to blender has about 5k vertices and 10k triangles.

When I export that model into Unreal (as .fbx file), Unreal reads it as 20k vertices but again 10k triangles.

Why does Unreal see about x3 vertices? Is there something I am doing wrong, something I don’t understand or it is simply the way it works?

Thanks in advance :slight_smile:

To do smoothing, UE4 will split the mesh along smoothing angles to separate smoothing. For example, if you have a cube, normally it would have 8 vertices, but when you import it to UE4 it will have 32

Is there a way to “skip” that or is it something that will always happen?

If it doesn’t do it then all of the polygons will be smoothed together, so if you want to have any hard edges then it is necessary

Thank you, and one more thing; for future reference, if I want a model to have them all smoothed together, how do I do that?
And thank you for the rapid response!

I’m not sure how you would do it in Blender, there’s some smoothing options when you import to UE4–that can apply an automatic smoothing or use the settings in the file. In 3ds Max it’s very easy where you just select all the polygons and set them to the same smoothing group.

Actually, it’s not just the smoothing. Due to the way GPUs work, a vertex in a buffer can only be shared between multiple triangles if all of that vertex’ attributes (position, normal, color, UV coordinates) are identical. If any of those is different across the triangles that share the vertex (normals in a flat-shaded cube, for example), a new vertex has to be created to store the different values (same position, different normals).

So, it’s Blender that is “under counting” the number of vertices, when it comes to GPU workload.

This whole thing is like a revelation to me right now xD
I will further explore Blender settings and options.
Thank you!

If different UV coordinates can cause this issue, I am going to take a wild guess that this UV horror is attributing to the under count.

Unless you properly unwrap the mesh, you will discover that also lightmass will be creating some horror lightmaps…

Just tried it in… 90% overlap.
Looks like I still have a LOT to learn. Starting with things like how to properly unwrap.

@ColdFireish

Years ago, a made a short kind of tutorial.
Although its done in max, not blender, it might give you a good overall idea…

https://www.youtube.com/watch?v=homulNbrD-8

Well, for things like buildings it’s pretty much impossible to use much less than 3x the vertices. It’s normal, don’t fret about it. Organic models like characters or rounded continuous surfaces are pretty much the only situation where you have some vertex reuse.

Thank you all for your responses, it helped a lot!