devkitPro

I am currently working on a graphical rpg using GX and I would like to know how to do physics in it. do I have to use an engine or what??

This depends on what kind of physics you want. Simple movements can be done by manually programming Newton's and Euler's Law.
For more complex dynamics (especially in 3D space), such as impacts, collisions or multi-body dynamics you should look into physics
libraries like ODE (ode.org).

http://www.box2d.org/

Might be another option.

I think box2d is only for 2d programs, not 3d programs.

you can also try nitroengine:
http://antoniond.drunkencoders.com/nitroengine.html

Hey again,

does this work with devkitpro?

whoops, didn't realise that this was in the devkitPPC forum. sorry about that.

yea, nitroengine is only for DS with devkitARM.

Do you know any 3D wii ones.