[MUD-Dev2] TECH: The maths behind 3D rendering ?

[Matt Owen]

Hi all,
 
Bit of a strange one this. I like coding challenges, I also like re-inventing the wheel for the sheer hell of it. :)
 
I've been dabbling with writing a maze/D&D type game on Windows Mobile, and I wanted to render the maze in 3D, first person Wolf3D/Doom style. Nothing complicated, straight passages square rooms etc. no ups or down.
 
Now I thought I knew the maths to make this happen, but i've become stuck, i just can't get certain poylgons to render correctly. So I'm thinking I need to read-up and find out what parts of the transformations i'm getting wrong. My maths is pretty good, but I think I'm mis-remembering how to do some things.
 
I've tried to find stuff on the web, but everyone these days just talks about using pre-supplied 3d engines or librarys with function names like RenderFilledPolygon - which doesn't help me, especially considering the target hardware I'm working on.
 
So I'm wondering (as I know many of you are long term professional game coders), whether someone can point me in the right direction of some information on the maths behind 3D transformations, ie. point of origin stuff, and vantage points etc ?
 
Cheers,
 
-Jar