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Misa 1e9fb6aac0 Generalize game loop order and fix it to what it was in 2.2 
Okay, so the reason why all render functions were moved to the end of
the frame in #220 is because it's simpler to call two fixed functions
and then a delta function instead of one fixed function, then a delta
function, and then another fixed function.

This is because fixed functions need special handling inside
deltaloop(), and you can't simply duplicate this handling after calling
a delta function. Oh, and to make matters worse, it's not always
fixed-delta-fixed, sometimes (like in MAPMODE and TELEPORTERMODE) it's
delta-fixed-fixed, so we'd need to handle that somehow too.

The solution here is to generalize the game loop and factor out each
function, instead of hardcoding it. Instead of having hardcoded
case-switches directly in the loop, I made a function that returns an
array of functions for a given gamestate, along with the number of
functions, then the game loop processes it accordingly. In fixedloop(),
it iterates over the array and executes each function until it reaches a
delta function, at which point it stops. And when it reaches the end of
the array, it goes back to the start of the array.

But anyway, if it gets to a delta function, it'll stop the loop and
finish fixedloop(). Then deltaloop() will call the delta function. And
then on the next frame, the function index will be incremented again, so
fixedloop() will call the fixed functions again.

Actually, the previous game loop was actually made up of one big loop,
with a gamestate function loop nested inside it, flanked with code that
ran at the start and end of the "big loop". This would be easy to handle
with one loop (just include the beginning and end functions with the
gamestate functions in the array), except that the gamestate functions
could suddenly be swapped out with unfocused functions (the ones that
run when you unfocus the window) at any time (well, on frame boundaries,
since key.isActive only got checked once, guarding the entire "inner
loop" - and I made sure that changing key.isActive wouldn't immediately
apply, just like the previous game loop order) - so I had to add yet
another layer of indirection, where the gamestate functions could
immediately be swapped out with the unfocused functions (while still
running the beginning and end code, because that was how the previous
loop order worked, after all).

This also fixes a regression that the game loop that #220 introduced
had, where if the fixed functions switched the gamestate, the game would
prematurely start rendering the gamestate function of the new gamestate
in the deltaframes, which was a source of some deltaframe glitches. But
fixing this is likely to just as well cause deltaframe glitches, so it'd
be better to fix this along with fixing the loop order, and only have
one round of QA to do in the end, instead of doing one round after each
change separately.

Fixes #464... but this isn't the end of the patchset. There are bugs
that need to be fixed, and kludges that need to be reverted.
2021-03-21 02:55:42 -04:00
.github Run CI on CentOS 7 (#574) 2021-01-11 00:30:15 -05:00
desktop_version Generalize game loop order and fix it to what it was in 2.2 2021-03-21 02:55:42 -04:00
mobile_version Fix 1x1 quicksand collision optimization not working 2020-05-13 08:16:34 -04:00
third_party Remove TinyXML-1 2020-06-12 15:08:29 -04:00
tools Adding original mapping tools for the sake of completeness 2020-01-12 19:49:24 +01:00
.gitattributes fix actionscript misclassified as angelscript 2020-01-12 15:18:45 -05:00
License exceptions.md Update License exceptions.md 2020-11-23 16:33:54 +10:30
LICENSE.md Updated link to Make and Play edition 2020-01-13 19:37:50 +01:00
README.md Update README.md 2020-01-10 17:45:29 +01:00

README.md

This is the source code to VVVVVV, version 2.0+. For more context about this release, see the announcement on Terry's blog!

License

VVVVVV's source code is made available under a custom license. See LICENSE.md for more details.

In general, if you're interested in creating something that falls outside the license terms, get in touch with Terry and we'll talk about it!

Authors

Versions

There are two versions of the VVVVVV source code available - the desktop version (based on the C++ port, and currently live on Steam), and the mobile version (based on a fork of the original flash source code, and currently live on iOS and Android).