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mirror of https://github.com/TerryCavanagh/VVVVVV.git synced 2024-06-28 15:38:30 +02:00
VVVVVV/desktop_version
Info Teddy 2687090ac2 Fix frame-ordering backspacing empty line bug in script editor
There is a long-standing bug with the script editor where if you delete
the last character of a line, it IMMEDIATELY deletes the line you're on,
and then moves your cursor back to the previous line. This is annoying,
to say the least.

The reason for this is that, in the sequence of events that happens in
one frame (known as frame ordering), the code that backspaces one
character from the line when you press Backspace is ran BEFORE the code
to remove an empty line if you backspace it is ran. The former is
located in key.Poll(), and the latter is located in editorinput().

Thus, when you press Backspace, the game first runs key.Poll(), sees
that you've pressed Backspace, and dutifully removes the last character
from a line. The line is now empty. Then, when the game gets around to
the "Are you pressing Backspace on an empty line?" check in
editorinput(), it thinks that you're pressing Backspace on an empty
line, and then does the usual line-removing stuff.

And actually, when it does the check in editorinput(), it ACTUALLY asks
"Are you pressing Backspace on THIS frame and was the line empty LAST
frame?" because it's checking against its own copy of the input buffer,
before copying the input buffer to its own local copy. So the problem
only happens if you press and hold Backspace for more than 1 frame.
It's a small consolation prize for this annoyance, getting to
tap-tap-tap Backspace in the hopes that you only press it for 1 frame,
while in the middle of something more important to do like, oh I don't
know, writing a script.

So there are two potential solutions here:

 (1) Just change the frame ordering around.

     This is risky to say the least, because I'm not sure what behavior
     depends on exactly which frame order. It's not like it's key.Poll()
     and then IMMEDIATELY afterwards editorinput() is run, it's more
     like key.Poll(), some things that obviously depend on key.Poll()
     running before them, and THEN editorinput(). Also, editorinput() is
     only one possible thing that could be ran afterwards, on the next
     frame we could be running something else entirely instead.

 (2) Add a kludge variable to signal when the line is ALREADY empty so
     the game doesn't re-check the already-empty line and conclude that
     you're already immediately backspacing an empty line.

I went with (2) for this commit, and I've added the kludge variable
key.linealreadyemptykludge.

However, that by itself isn't enough to fix it. It only adds about a
frame or so of delay before the game goes right back to saying "Oh,
you're ALREADY somehow pressing backspace again? I'll just delete this
line real quick" and the behavior is basically the same as before,
except now you have to hit Backspace for TWO frames or less instead of
one in order to not have it happen.

What we need is to have a delay set as well, when the game deletes the
last line of a char. So I set ed.keydelay to 6 as well if editorinput()
sses that key.linealreadyemptykludge is on.
2020-01-19 08:37:14 -05:00
..
src Fix frame-ordering backspacing empty line bug in script editor 2020-01-19 08:37:14 -05:00
.gitignore Ignore .gch files 2020-01-12 22:34:50 -05:00
CMakeLists.txt Untested Haiku port? 2020-01-13 23:31:14 -05:00
CONTRIBUTORS.txt add myself to CONTRIBUTORS.txt (with LC_COLLATE=C ordering) 2020-01-16 09:48:58 -05:00
README.md macOS builds also require self-built Vorbisfile 2020-01-14 10:16:15 -05:00

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

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