942217f871
There is this issue with conveyors where if you collide with them, your intended next y-position doesn't get updated to the position of the conveyor, and then your y-position gets set to your intended next y-position. This also applies to horizontally moving platforms. This bug used to not produce any problems, if at all, until #502 got merged. Since then, respawning from checkpoints that are on conveyors would sometimes not update your y-position at all, making it possible to get stuck inside a death loop that would require you to exit the game and re-enter it. But you can always reliably create this bug simply by going into the editor and placing down a conveyor and checkpoint on top of each other. Then enter and exit playtesting a bunch of times, and you'll notice the glitchy y-position Viridian keeps taking on. The root cause of this is how the game moves the player whenever they stand on the top or bottom of a conveyor (or a horizontally moving platform). The game sets their intended next x-position (newxp), then calls obj.entitymapcollision() on them. This would be okay, except their intended next y-position (newyp) doesn't get set along with their newxp, so entitymapcollision() will use the wrong newyp, then find that there is nothing that will collide with the player at that given newyp, then update the yp of the player to the wrong newyp. So, the platform logic simply doesn't set the player's newyp. Why does the player have the wrong newyp? It's because moving platforms (and conveyors) are updated first before all other entities are, and this includes the code that checks the player for collisions with moving platforms. That's right: the moving platform collision code gets ran before the player properly gets updated. This means that the game will use the newyp of the previous frame, which could be anything, really, but it most likely just means the intended next y-position of the player gets canceled, leaving the player with the same y-position they had before. Okay, but this bug only seems to happen when you put a checkpoint inside a conveyor (or a moving platform that hasn't started moving yet) and start playtesting from it, so why doesn't this bug happen more often, then? Well, it's probably because of luck and coincidence. Most of the time, if you're colliding with a conveyor or horizontally moving platform, you probably have a correct newyp from the previous frame of the game, so there'd be no problems. And before #502 got merged, this previous frame would be provided by the player having to fall to the surface due to the y-offset of their savepoint. However, if you make it so that you immediately teleport on to a conveyor (because you died), then this bug will rear its ugly head. |
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| README.md | ||
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 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