@Anonymous ,
Well I feel like there are more questions to be asked about your particular situation, but to get us started, here's some stuff you need to know..
Here's the DXF documentation about a 3DFace:
https://help.autodesk.com/view/OARX/2020/ENU/?guid=GUID-747865D5-51F0-45F2-BEFE-9572DBC5B151
A 3DFace can ONLY have 3 OR 4 sides.
If 3 sides, no triangulation necessary, a single plane is created. The DXF vertex values would look like so:
Vertex 1: {[DXF 10], [DXF 20], [DXF 30]}
Vertex 2: {[DXF 11], [DXF 21], [DXF 31]}
Vertex 3: {[DXF 12], [DXF 22], [DXF 32]}
If 4 sides, there are 2 triangles created, with the "crease" ALWAYS connecting, by default, between vertices 2 and 4.
Therefore, your vertex values would look like so:
Vertex 1: {[DXF 10], [DXF 20], [DXF 30]}
Vertex 2: {[DXF 11], [DXF 21], [DXF 31]}
Vertex 3: {[DXF 12], [DXF 22], [DXF 32]}
Vertex 4: {[DXF 13], [DXF 23], [DXF 33]}
...and your 2 triangles, like so:
Triangle 1: Vertex 1: {[DXF 10], [DXF 20], [DXF 30]}
Triangle 1: Vertex 2: {[DXF 11], [DXF 21], [DXF 31]}
Triangle 1: Vertex 4: {[DXF 13], [DXF 23], [DXF 33]}
Triangle 2: Vertex 2: {[DXF 11], [DXF 21], [DXF 31]}
Triangle 2: Vertex 3: {[DXF 12], [DXF 22], [DXF 32]}
Triangle 2: Vertex 4: {[DXF 13], [DXF 23], [DXF 33]}
Does that help?
EDIT:
Also, to be SUPER clear... a 3DFace ALWAYS saves 4 vertices (whether 3 or 4 sided).. If the 3rd and 4th vertex are the SAME coordinates, then the 3DFace is only 3 sided.. that's how you tell.
Best,
~DD
