This is because their oldxp wasn't being updated when they move (or
rather, teleport) and wrap around the screen.
These enemies are ZZT centipedes, but they're referred to as ASCII
snakes in comments in the code.
Okay, so the problem here is that Graphics::setcol() is called right
before a sprite is drawn in a render function, but render functions are
done in deltatime, meaning that the color of a sprite keeps being
recalculated every time. This only affects sprites that use fRandom()
(the other thing that can dynamically determine a color is help.glow,
but that's only updated in the fixed-timestep loop), but is especially
noticeable for sprites that flash wildly, like the teleporter, trinket,
and elephant.
To fix this, we need to make the color be recalculated only in the
fixed-timestep loop. However, this means that we MUST store the color of
the sprite SOMEWHERE for the delta-timesteps to render it, otherwise the
color calculation will just be lost or something.
So each entity now has a new attribute, `realcol`, which is the actual
raw color used to render the sprite in render functions. This is not to
be confused with their `colour` attribute, which is more akin to a color
"ID" of sorts, but which isn't an actual color.
At the end of gamelogic(), as well as when an entity is first created,
the `colour` is given to Graphics::setcol() and then `realcol` gets set
to the actual color. Then when it comes time to render the entity,
`realcol` gets used instead.
Gravitron squares are a somewhat tricky case where there's technically
TWO colors for it - one is the actual sprite itself and the other is the
indicator. However, usually the indicator and the square aren't both
onscreen at the same time, so we can simply switch the realcol between
the two as needed.
However, we can't use this system for the sprite colors used on the
title and map screen, so we'll have to do something else for those.
Just to make sure it's extra smooth. Not that it will be noticeable, and
you can't access the Secret Lab in slowmode without modifying the game,
but it's nice to have this.
This has to be done in order to fix rendering when on a conveyor or
moving platform and actively moving with or against it. Pretty sure this
shouldn't break anything, oldxp/oldyp is mostly visual after all (and by
the time it's used for gravity line collision checking,
updateentitylogic() would've already gotten around to it anyway).
Incidentally, this also fixes a jitter that would occur if you were
moving at the time you died or collected a trinket or custom crewmate,
due to the game temporarily freezing and either doing deathsequence or
completestop.
This fixes entities being drawframe 0 for 1 frame when being first
created. Incidentally, this also fixes entities created during
completestop being the player sprite, too, which is something not many
people notice.
This prevents undefined behavior because we use oldxp/oldyp to do linear
interpolation.
It's also initialized in entclass::entclass(), just to be sure. And I've
deduplicated the regular xp/yp initialization in createentity(), too.
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.
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);'.
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.
Instead of using somewhat-obtuse for-loops to initialize or reset these
vectors, it takes up less lines of code and is clearer if we use
std::vector::resize() and std::vector::clear() instead.
We need to replace an "or" with an "and".
My best guess for this oversight happening was because of the weird
ordering. The code originally did "temp < 30" first and "temp > -30"
second instead of the other way around. With the weird ordering, it
becomes more natural to insert an "or" instead of an "and". So I swapped
around the ordering just for good measure.
This is also fixed in the mobile version.
Due to the previous commit, these will no longer be regularly taking in
out-of-bounds entity indices. Or at least they shouldn't, so I'm putting
in these print statements here on the off-chance that they do.
Otherwise, this would result in the game updating an entity twice, which
isn't good. This is most noticeable in the Gravitron, where many
Gravitron squares are created and destroyed at a time, and it's
especially noticeable during the part near the end of the Gravitron
where the pattern is two Gravitron squares, one at the top and bottom,
and then two Gravitron squares in the middle afterwards. The timing is
just right such that the top one of the two middle ones would be
misaligned with the bottom one of the two when a Gravitron square gets
outside the screen.
To do this, I changed entityclass::updateentities() into a bool, and
made every single caller check its return value. I only needed to do
this for the ones preceding updateentitylogic() and
entitymapcollision(), but I wanted to play it safe and be defensive, so
I did it for the disappearing platform kludge, as well as the
updateentities() within the updateentities() function.
The main ones to beware of here are entityclass::updateentities(),
entityclass::updateentitylogic(), and entityclass::entitymapcollision().
They would index out-of-bounds and thus commit Undefined Behavior if the
entity was removed in entityclass::updateentities(). And it would've
been fine enough if I only added bounds checks to those functions.
However, I decided to be a bit more defensive and play it safe, and
added bounds checks to ALL functions taking in not only an entity
indice, but also blocks and linecrosskludge indices.
It's treated like a bool anyway, so might as well make it one.
This also necessitates updating every single instance where it or an
element inside it is used, too.
game.trinkets is supposed to be correlated with obj.collect, however why
not just count obj.collect directly?
This turns game.trinkets into a function, game.trinkets(), which will
directly count the number of collected trinkets and return it. This will
fix a few corner cases where the number of trinkets can desync with the
actual collection statuses of trinkets.
In order to keep save compatibility with previous versions of VVVVVV,
the game will still write the <trinkets> variable. However, it will not
read the <trinkets> variable from a save file.
Whenever you collect a trinket, game.stat_trinkets gets updated (if
applicable) to signify the greatest amount of trinkets you have ever
collected in the game. However, custom levels shouldn't be able to
affect this, as their trinkets are not the same trinkets as the main
game.
Just like earlier, these are of the form
if (cond1) { if (cond2) { if (cond3) { thing; } } }
and are really annoying to read.
Also this removes the remnants of the 'active' system that have been
replaced with 'if (true)' conditionals in order to not add noise to the
diff.
This removes the variables obj.nblocks, as well as removing the 'active'
attribute from the block object. Now every block is guaranteed to be
real without having to check the 'active' variable.
Removing a block while iterating now uses the removeblock_iter() macro.
I guess these were here earlier when there were 'active' conditionals,
but then I removed those, so now they look weird next to the 'i != j'
conditionals, so I'm removing them.
These would be of the form
if (cond1) { if (cond2) { if (cond3) { thing; } } }
which is really annoying to read and could've been written as
if (cond1 && cond2 && cond3) { thing; }
so that's what I'm fixing here.
There will be another commit later that fixes this but in places related
to blocks.
Not sure why this function is here. It makes sense if you know that the
game will only do certain moving platform things if you already have a
moving platform in the room, however apparently this function has
absolutely nothing to do with it.
This function's sole purpose was to make sure obj.nentity was in sync,
and that obj.nentity-1 pointed to the last 'active' entity in
obj.entities. But now that obj.nentity is removed and we use
obj.entities.size() instead, it is no longer necessary.
In the previous commit, if an if-statement consisted solely of checking
the active attribute of an entity, I temporarily changed it to 'true'
and put a comment to remove it later, because it would add too much
noise to unindent everything in the same commit.
This removes the variables obj.nentity and obj.nlinecrosskludge, as well
as removing the 'active' attribute from the entity class object. Now
every entity you access is guaranteed to be real and you don't have to
check the 'active' variable.
The biggest part of this is changing createentity() to modify a
newly-created entity object and push it back instead of already
modifying an indice in obj.entities.
As well, removing an entity now uses the new obj.removeentity() function
and removeentity_iter() macro.
Ok, once we switch everything over to not use the 'active' system, it's
easier to read removeentity(t) than it is to read
entities.erase(entities.begin() + t).
This moves the setenemyroom() function onto the entity object itself, so
I can more easily change all 'entities[k].' to 'entity.' in
entityclass::createentity() later.
Additionally, I've had to move the rn() macro from Entity.h to Ent.h, or
else entclass::setenemyroom() won't know what it is.
This moves the setenemy() function onto the entity object itself,
instead of having to give the indice of the entity in obj.entities. This
makes the code more object-oriented so later I can simply change all
'entities[k]' to 'entity.' in entityclass::createentity().
This changes something like UtilityClass::String to help.String,
basically. It takes less typing this way, and is a neat effect of having
global args actually be global variables.
