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.
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