Win32/OpenGL version available

The Win32 / OpenGL version is available now! Although I loved DOS programming, you won't believe how great it is to finally get this hardware accelerated rendering. :-)

Please note the current nomenclature: Ca3D refers to the DOS version executable, which is still included in the download package. Ca3Dgl refers to the new Win32 / OpenGL version executable. I know that I am introducing a lot of confusion with this, especially in the readme files. The name of the engine is still Ca3D, only the OpenGL executable is suffixed to avoid mix-ups. If I stop maintaining the DOS version someday, I'll have to clean this up.