1f5835c985
The previous fade system used only one variable, the amount of volume to fade per frame. However, this variable was an integer, meaning any decimal portion would be truncated, and would lead to a longer fade duration than intended. The fade per volume is calculated by doing MIX_MAX_VOLUME / (fade_ms / game.get_timestep()). MIX_MAX_VOLUME is 128, and game.get_timestep() is usually 34, so a 3000 millisecond fade would be calculated as 128 / (3000 / 34). 3000 / 34 is 88.235..., but that gets truncated to 88, and then 128 / 88 becomes 1.454545..., which then gets truncated to 1. This essentially means 1 is added to or subtracted from the volume every frame, and given that the max volume is 128, this means that the fade lasts for 128 frames. Now, instead of the fade duration lasting 3 seconds, the fade now lasts for 128 frames, which is 128 * 34 / 1000 = 4.352 seconds long. This could be fixed using floats, but when you introduce floats, you now have 1.9999998 problems. For instance, I'm concerned about floating-point determinism issues. What I've done instead is switch the system to use four different variables instead: the start volume, the end volume, the total duration, and the duration completed so far (called the "step"). For every frame, the game interpolates which value should be used based on the step, the total duration, and the start and end volumes, and then adds the timestep to the step. This way, fades will be correctly timed, and we don't have potential determinism issues. Doing this also fixes inaccuracies with the game timestep changing during the fade, since the timestep is only used in the calculation once at the beginning in the previous system. |
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| src | ||
| .dockerignore | ||
| .gitignore | ||
| CMakeLists.txt | ||
| CONTRIBUTORS.txt | ||
| Dockerfile | ||
| README.md | ||
| version.cmake | ||
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 2.0.14+ and SDL2_mixer. All other dependencies are statically linked into the engine. The development libraries for Windows can be downloaded from their respective websites, Linux developers can find the dev libraries from their respective repositories, and macOS developers should compile and install from source (including libogg/libvorbis/libvorbisfile).
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/SDL2_mixer folders somewhere nice!
mkdir flibitBuild
cd flibitBuild
cmake -G "Visual Studio 10 2010" .. -DSDL2_INCLUDE_DIRS="C:\SDL2-2.0.10\include;C:\SDL2_mixer-2.0.4\include" -DSDL2_LIBRARIES="C:\SDL2-2.0.10\lib\x86\SDL2;C:\SDL2-2.0.10\lib\x86\SDL2main;C:\SDL2_mixer-2.0.4\lib\x86\SDL2_mixer"
Note that on some systems, the SDL2_LIBRARIES list on Windows may need
SDL2/SDL2main/SDL2_mixer to have .lib at the end of them. The reason for this
inconsistency is unknown.
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 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 for more details. (If you've got a project in mind that requires distributing this file, get in touch!)
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