Background

I have been trying to import an icosahedron mesh into Unreal from Blender, in such a way that every tri in the mesh has 3 distinct vertices stored. This is so I can then do some maths on those tris, move every tri around separately, and the like.

But no matter what I try, Unreal won’t give me the full set of vertices.

Simplified Problem

So I simplified the problem as much as I can by making a simple cube in Blender, with 36 vertices. That is: 6 sides, 2 triangles per side, 3 distinct verts per tri. 36 vertices.

It turns out I can’t even get this cube into Unreal with all 36 vertices intact. I only ever get the 24 verts you might typically expect. 6 square sides, 4 verts per side.

Things I’ve Tried

• The cube mesh in Blender has been:

  • Triangulated (modifier)

  • Edge Split

  • Mark Seams

  • Shade Flat

  • Triangulated again (on export)

  • In other words, everything I can think of to be clear that I want 3 verts per tri. This displays 36 verts in Blender before exporting.

• Opening the exported OBJ file in:

  • Blender

  • Notepad

  • 3D Viewer

  • … all state 36 vertices. Only Unreal still says 24.

• Exporting with FBX gives the same result in Unreal.

• With a much larger mesh (my icosahedron), I might get a small different in which vertices exactly are discarded, between FBX, OBJ, or various import settings, but hundreds of vertices are still discarded regardless of approach.

• I have tried every import/export option I can think of in both Blender and Unreal.

The Question

I am getting the impression that no matter what, if Unreal finds 2 vertices in an import file with the same position and normal, it will turn them into 1 vertex… even when that means that once-separable tris become no longer separable.

So my question is:

• Is is actually possible to import a mesh into Unreal while keeping all duplicate vertices intact?

• If so, how?

Ie., How can I import a cube with 36 vertices from Blender into Unreal, while keeping all 36 vertices? Or is this not possible?