i was jsut wondering would it be faster to work out the 2d screen coords to draw the 3d stuff(which would be easy) and draw everything in 2d with ogl than to use ogl’s 3d features?
No, probably no difference at all.
When you draw in 2D in OpenGL you’re really drawing in 3D with the z-coord set to 0. All the same calculations will be going on, so there’s no real advantage to 2D. Your extra calculations to convert your 3D scene into 2D will be redundant, and actually slow the system down.
OpenGL has been designed as a 3D API, and it works very well as intended. Don’t be afraid to use it as such.