CODEWITHSUNDEEP
c++functionheaderc-preprocessormultiplatform
thornblom
thornblom

Reputation: 13

Adding a preprocessor #define to change which headers are included and which functions are called

I'm developing a game engine for Sega Dreamcast and Windows. I have implemented my own library for the Dreamcast hardware, which pretty much does the same thing as OpenGL for PC. Now, I want to merge the two builds into one project, so I don't need to dev to different project doing the exact same high level stuff.

I know you can add a preprocessing line like this: #define DREAMCAST, and then the Dreamcast headers will be included and the appropriate low level function will be called instead of OpenGL. This has been done before, but I don't know how to make that possible.

This has really nothing to do with Dreamcast, it could be Mac, Linux or whatever. I have different compilers for each platform. So when #define DREAMCAST, I want the G++ KOS compiler to include the Dreamcast-specific headers and classes. If #define DREAMCAST is not present, I want MingGW to include the Windows OpenGL headers and classes.

How can I do this?

Upvotes: 0

Views: 101

Answers (1)

danielschemmel
danielschemmel

Reputation: 11116

For the initial problem of including different versions depending on a predefined symbol, a simple solution is available:

#if defined(DREAMCAST)
#include <my_dreamcast_header>
#else
#include <opengl_header>
#endif

This functionality should be available on just about any C or C++ compiler - and it definitely is on MinGW. You still need to invoke the correct compiler yourself of course, as there is no way to change the compiler once compilation starts.

Upvotes: 1

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