c++ - Any tips for creating cross-platform games?

Do you have any tips/recommendations when creating a cross-platform game in C/C++?

Answer

Hide anything platform-specific behind abstraction layers

This means stuff like rendering, audio, user input, and file IO. One common trick to abstracting that without inducing a run-time performance penalty is platform-agnostic headers with platform-specific implementation files:

// FileSystem.h
class FileSystem {
public:
    FileHandle OpenFile(const char * path);
    // other stuff...
}

// FileSystemWindows.cpp

FileHandle FileSystem::OpenFile(const char * path) {
    // call windows API...
}

Then configure the builds for each platform to build against the proper .cpp file.

Make your content pipelines read in platform-independent assets and output platform-specific content for each platform

For example, author your textures as .tga or just .psd, then have a pipeline that can automatically convert those to the different platform-specific formats you need.

Don't assume a specific memory layout or endianness in your data

Platforms may vary in byte order, padding, alignment, and word size. Any code that cares about that must be thoroughly tested on all platforms.

Test on all platforms, all the time

You will get bitten by platform-specific bugs. Would you rather get bitten now, or right when you're trying to get the game out the door?