I’m wondering if there’s any inbuilt or user built support for things like Delaunays Triangulation that anyone knows of or whether I would have to create one myself? If I would have to implement it myself would it be best to use my own custom struct for the triangles or FPoly? If FPoly then are there any decent documentation on using it?
As far as I know there are no solutions related to that in Unreal. Unreal engine expect the models to be made outside of the engine where you DO have these functions and then later imported to UE4. However, if you have access to C++ you can include a third party library that does this for you. Any c++ third party library will do. Please have a look at this.
Firstly, I highly highly doubt something like an algorithm for Delaunays Triangulation is already built into the engine.
Are you trying to generate something at runtime?
As for normal Engine classes to look at, I would suggest UProceduralMeshComponent and UCustomMeshComponent.
If you want to try something made by the community, that is also free, I would suggest this: Runtime Mesh Lite in Code Plugins - UE Marketplace
He claims it is a lot better than the Engine version, which is probably true, as he has focused on it a lot lately, the Engine version might still be experimental.
I haven’t used it, but it might be worth a look.
What little documentation I could find on UProceduralMeshComponent:
It was experimental in 4.10, and I don’t know if it has improved since then.
Hope that helps get you started!