I've added a function Graphics::lerp() which simply interpolates between
two values given a certain alpha value. It's just like drawing a
straight line between two points.
Also, Graphics now has an `alpha` attribute, and it is set on every
deltatime update to be used in linear interpolation.
Ok, and this is where the fun starts.
In an ideal world, this would be the end of this patch. However, of
course, there are many, MANY places in the game that update
fixed-timestep timers DIRECTLY inside the render function, which is not
ideal because it means those timers go super fast.
I'll have to fix those later.
Ok, NOW indent it. I didn't indent it previously because the diffs are
annoying to read if there's an indent that doesn't otherwise change
anything (and even now it's pretty annoying to read).
Alright, this is the start of the over-30-FPS patch!
First things first, we'll need to make it possible to have a separate
deltatime loop outside of the fixed timestep loop. And for that, we
can't be using SDL_Delay(), as SDL_Delay() (as you might imagine) blocks
the whole program.
Instead we'll be using this thing called an accumulator. It looks at how
long the previous poll took (the raw deltatime), and lets timesteps pass
accordingly.
On a side note, I've had to split the `time` and `timePrev` declaration
each onto their own separate line, otherwise there's undefined behavior
from `time` not being initialized.
I use `accumulator = fmodf(...)` instead of `accumulator -=
timesteplimit` because otherwise it'll fast-forward if it's behind,
which is a jarring thing to see.
Also in preparation for what's going to come down the over-30-FPS road,
I've also added `deltatime` and `alpha`. `deltatime` is going to be used
if the game is in slowdown mode, and `alpha` is going to be used for
linear interpolation of animations.
By the way, what was the main game loop previously (and is now the new
timestep loop) is now in an extra set of curly braces, but I haven't
indented it yet to reduce the noise in this commit.
This prevents being able to "roll over" the amount of minutes to 0 (by
simply waiting for the timer to tick past one hour) and being able to
get a result of 00:13 when your result is really 01:00:13.
By looking only at the minutes, the game would read 01:00:13 as 00:13
instead. So simply add the amount of hours to the time trial result.
This is needed for MinGW when compiling C++98, apparently. I put it in
an if-guard because otherwise there'll be a warning from MY compiler
about redefinitions.
If you exited to the menu normally (i.e. got on a code path that went
through Game::quittomenu()), the menu music wouldn't play. This is
because FILESYSTEM_unmountassets() was put after music.play(6). So the
game would play the custom level's track 6, and then unmount it, which
meant it could no longer play track 6, but there's nothing telling the
game to play track 6 again. So I just changed the frame ordering around.
I also added a comment to make sure anyone reading the code is aware of
the frame order dependency.
If you exited from the editor, custom assets would not be unmounted. But
I made sure to put the FILESYSTEM_unmountassets() before the
music.play(6) because otherwise the menu music wouldn't play.
You could also exit to the menu from a custom level using the
rollcredits() command, so I made sure to put a
FILESYSTEM_unmountassets() when returning to the menu from the credits
as well. I also made sure to put it before the music.playef(18) so
there's no risk of the sound effect not playing properly, or not playing
the non-level-specific one.
I added a comment to both FILESYSTEM_unmountasset()s to make sure anyone
reading the code is aware of the frame order dependency.
This is really awful, but there's not much we can do.
TinyXML-2 no matter what will never stop on newlines, so without
changing the XML parser, this is the best we can do - just remove the
"\n " (that's a linefeed plus exactly 12 spaces) if it
appears at the end of the contents of an edentity tag.
Also a giant comment for good measure.
Looks like duplicate player entities persisting across rooms is a
semi-useful feature used by some levels. Still, though, it's a bit of a
nuisance to have duplicate player entities persisting across game
sessions. And levels can't rely on this persistence anyway, anyone could
just close the game and re-open it to get rid of the duplicate entities
regardless.
If a trinket or crewmate ID is out-of-bounds, it will not be created.
This is not only because the `collect`/`customcollect` check in
entityclass::createentity() would then be out-of-bounds, but also
touching it would also be out-of-bounds, too.
Display trinkets will always be created if the ID is out-of-bounds.
Apparently some people (@AllyTally) have been creating display trinkets
with IDs of -1 in order to get a display trinket that always shows up,
which is rather horrifying. But it makes sense, there's a lot more
nonzero int values than there are the amount of int values that are
zero, so it's fairly likely that the `collect` check will always come up
to be true (nonzero). Also, it's more useful to be able to have a
display trinket that always shows up without having to collect a trinket
beforehand, than it is to have it not be created (because technically by
default, you're already in the world where you don't have it created).
Display trinkets still have their `para` set to their ID, though, and if
they managed to gain an `onentity` of 1, bad things could happen... So
just to be sure, I added INBOUNDS checks to crewmates and trinkets in
entityclass::updateentities() so no UB will happen if you collect a
crewmate/trinket with an out-of-bounds ID. Also, I de-duplicated the
`collect`/`customcollect` setting, too.
The flashy color of the elephant can be hard on people's eyes,
especially if they're the type who want screen effects disabled because
they might have epilepsy. The elephant takes up a good 3/4ths of the
screen, you know. If screen effects are disabled, the elephant will use
color 22, which is a neutral gray.
I'm only adding this because the VVVVVV speedrun mods (@tzann, @mohoc)
invalidate all runs that have the elephant texture removed, even though
many people would be looking at a potentially epilepsy-inducing image
many times a day grinding 100% speedruns. (Imo, their justification for
this is flimsy at best.)
The only class that actually needs its i/j/k kept is scriptclass,
because some custom levels rely on it for creating custom activity
zones. So I haven't touched that.
Other than that, there's no chance that anything important relies on
i/j/k in any other class. For that to be the case, it would have to use
i/j/k without initializing it beforehand, and that can simply be
detected by removing the attribute from the header file and seeing where
the compiler complains. And the compiler complains only about cases
where it's initialized first. (Note that due to this check, I *haven't*
removed Graphics's `m` as it precisely does exactly this, using it
without initializing it first.)
Interestingly enough, otherlevelclass and towerclass have unused i/k
variables for whatever reason.
This prevents the game from being saved if you manage to trigger a
savetele() during a "special" gamemode (like if you use the Gravitron
out-of-bounds glitch when replaying Intermission 2, then go to Game
Complete that way).
If you don't have a font.txt, it could happen that a font index is
requested that's out-of-bounds. And that would result in a segfault. So
to fix that I'm adding INBOUNDS checks to all functions that index the
fontmap.
This fixes indexing out-of-bounds in the functions that draw all the
special images such as the elephant and teleporters. Let's make sure the
game doesn't segfault.
I tracked down all the functions that took in an entity's drawframe and
made sure that no matter what value an entity's drawframe was, the game
would never segfault.
To deal with using a different image file for Flip Mode, it looks like
copy-paste was used. This isn't exactly maintainable code. So I'm
replacing it with a reference that changes depending on if the game is
in Flip Mode or not, instead.
Removing the player entity has all sorts of nasty effects, such as
softlocking the game because many inputs require there to be a player
present, such as opening the quit menu.
The most infamous glitch to remove the player entity is the Gravitron
Fling, where the game doesn't see a gravity line at a specific
y-position in the current room, and when it moves the bottom gravity
line it moves the player instead. When the gravity line gets outside the
room, it gets destroyed, so if the player gets dragged outside the room,
they get destroyed, too. (Don't misinterpret this as saying anytime the
player gets dragged outside the room, they get destroyed - it's only the
Gravitron logic that destroys them.)
Also, there are many places in the code that use entity-getting
functions that have a fallback value of 0. If it was possible to remove
the player, then it's possible for this fallback value of 0 to index
obj.entities out-of-bounds, which is not good.
To fix this, entityclass::removeentity() is now a bool that signifies if
the entity was successfully removed or not. If the entity given is the
player (meaning it first checks if it's rule 0, just so in 99% of cases
it'll short-circuit and won't do the next check, which is if
entityclass::getplayer() says the indice to be removed is the player),
then it'll refuse to remove the entity, and return false.
This is a change in behavior where callers might expect
entityclass::removeentity() to always succeed, so I changed the
removeentity_iter() macro to only decrement if removing the entity
succeeded. I also changed entityclass::updateentities() from
'removeentity(i); return true;' to 'return removeentity(i);'.
Apparently it results in Undefined Behavior if the argument given isn't
representable as an unsigned char. This means that (potentially) plain
char and signed chars could be unsafe to use as well.
It's rare that this could happen in practice, though. std::isdigit() is
only used by is_positive_num() which is only used by find_tag(), so
someone would have to deliberately put something crazy after an `&#` in
a custom level file in order for this to happen. Still, better to be
safe than sorry and all.
This fixes a compile error that could happen where the compiler doesn't
know what std::isdigit() is, but I'm puzzled as to why this wasn't
happening earlier, 'cause I've only been reported that it happens by
only one person.
Continuing from #280, another potential source of out-of-bounds indexing
(and thus, Undefined Behavior badness) comes from script commands. A
majority of them don't do any input validation at all, which means the
potential for out-of-bounds indexing and segfaulting in custom levels.
So it's always good to add bounds checks to them.
Interesting note, the only existing command that has bounds checks is
the flag() command. That means you can't turn out-of-bounds flags on or
off. But there's no bounds checks for ifflag(), or customifflag(), which
means you CAN index out-of-bounds with those commands! That's a bit bad
to do, so.
Also, I decided to add the bounds checks for playef() at the
musicclass::playef() level, instead of just the level of the playef()
command. I don't know of any other cases outside of the command where
musicclass::playef() will index out of bounds, but musicclass is the one
containing the indexed vector anyway, I wanted to cover more cases, and
it's better to be safe than sorry.
And this the function with the least amount of cases where its sentinel
value is used unchecked. Thankfully. obj.getplayer() was a bit of a slug
to get through.
obj.getplayer() can return -1, which can cause out-of-bounds indexing of
obj.entities, which is really bad. This was by far the most changes, as
obj.getplayer() is the most used entity-getting function that returns
-1, as well as the most-used function whose sentinel value goes
unchecked.
To deal with the usage of obj.getplayer() in mapclass::warpto(), I just
added general bounds checks inside that function instead of changing all
the callers.
