How to Build
------------
VVVVVV's official desktop versions are built with the following environments:

- Windows: Visual Studio 2010
- macOS: Xcode CLT, currently targeting 10.9 SDK
- GNU/Linux: CentOS 7

The engine depends solely on [SDL2](https://libsdl.org/) 2.24.0+. All other dependencies
are statically linked into the engine. The development libraries for Windows can
be downloaded from SDL's website, Linux developers can find the dev libraries from their
respective repositories, and macOS developers should compile and install from source.
(If you're on Ubuntu and your Ubuntu is too old to have this SDL version, then
[see here](https://github.com/TerryCavanagh/VVVVVV/issues/618#issuecomment-968338212)
for workarounds.)

Since VVVVVV 2.4, git submodules are used for the
[third party libraries](https://github.com/TerryCavanagh/VVVVVV/tree/master/third_party).
After cloning, run `git submodule update --init` to set all of these up.
You can also use this command whenever the submodules need to be updated.

Steamworks support is included and the DLL is loaded dynamically, you do not
need the SDK headers and there is no special Steam or non-Steam version. The
current implementation has been tested with Steamworks SDK v1.46.

To generate the projects on Windows:
```
# Put your SDL2 folders somewhere nice!
mkdir flibitBuild
cd flibitBuild
cmake -A Win32 -G "Visual Studio 10 2010" .. -DSDL2_INCLUDE_DIRS="C:\SDL2-2.24.0\include" -DSDL2_LIBRARIES="C:\SDL2-2.24.0\lib\x86\SDL2;C:\SDL2-2.24.0\lib\x86\SDL2main"
```

Note that on some systems, the `SDL2_LIBRARIES` list on Windows may need
SDL2/SDL2main to have `.lib` at the end of them. The reason for this
inconsistency is unknown.

Also note that if you're using a Visual Studio later than 2010, you will need to
change the `-G` string accordingly; otherwise you will get a weird cryptic
error. Refer to the list below:

- VS 2012: `"Visual Studio 11 2012"`
- VS 2013: `"Visual Studio 12 2013"`
- VS 2015: `"Visual Studio 14 2015"`
- VS 2017: `"Visual Studio 15 2017"`
- VS 2019: `"Visual Studio 16 2019"`
- VS 2022: `"Visual Studio 17 2022"`

To generate everywhere else:
```
mkdir flibitBuild
cd flibitBuild
cmake ..
```

macOS may be fussy about the SDK version. How to fix this is up to the whims of
however Apple wants to make CMAKE_OSX_SYSROOT annoying to configure and retain
each time Xcode updates.

Including data.zip
------------
You'll need the data.zip file from VVVVVV to actually run the game! It's
available to download separately for free in the
[Make and Play](https://thelettervsixtim.es/makeandplay/)
edition of the game. Put this file next to your executable and the game should
run.

This is intended for personal use only - our license doesn't allow you to
actually distribute this data.zip file with your own forks without getting
permission from us first. See [LICENSE.md](../LICENSE.md) for more details. (If
you've got a project in mind that requires distributing this
file, [get in touch](http://distractionware.com/email/)!)

A Word About Compiler Quirks
----------------------------

_(Note: This section only applies to version 2.2 of the source code, which is
the initial commit of this repository. Since then, much hard work has been put
in to fix many undefined behaviors. If you're compiling the latest version of
the source code, ignore this section.)_

This engine is _super_ fussy about optimization levels and runtime checks. In
particular, the Windows version _absolutely positively must_ be compiled in
Debug mode, with /RTC enabled. If you build in Release mode, or have /RTC
disabled, the game behaves dramatically different in ways that were never fully
documented (bizarre softlocks, out-of-bounds issues that don't show up in tools
like Valgrind, stuff like that). There are lots of things about this old code
that could be cleaned up, polished, rewritten, and so on, but this is the one
that will probably bite you the hardest when setting up your own build,
regardless of platform.

We hope you'll enjoy messing with the source anyway!

Love, flibit
