Help me !!! PC ---- Mac problem

Judging from the nature of your question, it is obvious you know
little about Operating Systems, and what is involved, nor hardware architecture. I will attempt to answer your question as well as I can.
You will not be able to write games for Macintosh until you fully understand how to program for the MAC RISC based OS, and
THAT in conjunction with their graphics cards.
Windows is a 32-bit operating system, and mac is 64 bit.
Not compatible, you see. There is no "convertor", either.
You will be better off concentrating on windows, as it is by
a massive legion greater the choice of computers on the market,
MAC being crippled software-wise by low selection and NON-COMPATIBILITY with software made for Windows...

He still didn''t really answer your question. If you want to make a project that runs on both Macs and PCs you have to use OpenGL. DX8 is only supported on Windows, while OpenGL is multiplatform. You could rewrite all your graphics code in OpenGL on the Mac after doing writing the DX8 code on PC, but it will be easier to do everything in GL.

Yea, OpenGL would work for both platforms. However, DX8 covers 2d/3d graphics, sound, input, net, music, and video streaming. Plus Win32 is used for window creation and perhaps other system tasks like timers and installers. All of those other parts will have to be ported since OpenGL will just cover the graphics. It''s not like by using OpenGL you all of a sudden get versions for all platforms that support OpenGL. Also, game logic code would be different when dealing with optimizations for a platform.

My suggestion to the poster, just do one platform for now. Then worry about making a port. To answer the question, you cannot use DX8 on Mac. DirectX is a Windows API.