If you really want to do it from zero, then it will be rather a long journey than a simple "project". If you have plenty of time and motivation then you`ll have nice results in 2-3 years(depending on how good you are at maths/3D maths.)
-You not just have to learn C++ ...but OOP prorgramming itself, lots of maths, 3D maths, physics, directX / openGL, (a sound API and networking ...optionally) etc.
If you dont wanna create your own 3D models ....just import them from an other program ...thats saves a lot of time.
-It makes more sense to build up your engine incrementally and create actual games along the way, ....cause you can spend months with working on things that make your engine more solid but dont add anything to the graphics. .....it can be quite demotivating.
-And you need to have 2D projects too. ....with many things its better to have a good understanding of them in 2D before doing the dimension jump:)
....anyway Wolf 3D and Doom1 are not really 3D games, but 2D games with 3D(ish) graphics.
Sounds like an ideal plan, and yeah I'd begin with simple 2d engines, games etc at first, learn how it all slots together etc. I guess I wouldn't expect to be able to make a Wolf3d clone for a few years yet, but it's my goal. I dream of being able to make just some kind of generic 3d fps engine, even if it was never good enough to be sold or used commercially, just something to toy with and use to learn, but it's one of the things that's on the cards for the next decade of my life, or optimistically, 5 years.
As for 3d models, I should be able to build most of them myself, I've done a level design, 3d modeling and 3d animation before. I've done a bucketload of mod work over the last 10 years in Doom/2, Build engine, Source Engine and Unreal. Have also built a lot of special effects, so it would be fun to play around with some of these aspects from the coding side of things once I get the hang of it.
2-3 years sounds good, nothing good comes easy or fast, it just relieves me to know that it's not some 10 year endeavour, I don't want to end up making something half decent by the time my life is already more than halfway over.
Still, thanks for all the answers guys! I know I haven't replied to all of them but I've read all your responses.
Edited by James Miller, 26 January 2013 - 02:54 PM.