Specifically, we address three concerns (the image stretching during
rotation, artifacts around the image due to clamping to the nearest
border color when the image is drawn to a larger space than the image
itself takes up, and potential artifacts around a rotated image which
accidentally ended up in an atlas and didn't have enough extra space to
guarantee the rotation would work).
The first concern was addressed by fixing the dimensions of the map
images drawn from the UI (so that we always use a square source
rectangle, rather than a rectangular one according to the dimensions of
the map). We also fixed the way rotation was done in the fragment
shader for north-facing sources to make it properly handle aspect ratio
(this was already done for north-facing targets). Together, these fix
rendering issues peculiar to rectangular maps.
The second and third concerns were jointly addressed by adding an
optional border color to every 2D image drawn by the UI. This turns
out not to waste extra space even though we hold a full f32 color
(to avoid an extra dependency on gfx's PackedColor), since voxel
images already take up more space than Optiion<[f32; 4]> requires.
This is then implemented automatically using the "border color"
wrapping method in the attached sampler.
Since this is implemented in graphics hardware, it only works (at
least naively) if the actual image bounds match the texture bounds.
Therefore, we altered the way the graphics cache stores images
with a border color to guarantee that they are always in their own
texture, whose size exactly matches their extent. Since the easiest
currently exposed way to set a border color is to do so for an
immutable texture, we went a bit further and added a new "immutable"
texture storage type used for these cases; currently, it is always
and automatically used only when there is a specified border color,
but in theory there's no reason we couldn't provide immutable-only
images that use the default wrapping mdoe (though clamp to border
is admittedly not a great default).
To fix the maps case specifically, we set the border color to a
translucent version of the ocean border color. This may need
tweaking going forward, which shouldn't be hard.
As part of this process, we had to modify graphics replacement to
make sure immutable images are *removed* when invalidated, rather
than just having a validity flag unset (this is normally done by
the UI to try to reuse allocations in place if images are updated
in benign ways, since the texture atlases used for Ui do not
support deallocation; currently this is only used for item images,
so there should be no overlap with immutable image replacement,
so this was purely precautionary).
Since we were already touching the relevant code, we also updated
the image dependency to a newer version that provides more ways
to avoid allocations, and made a few other changes that should
hopefully eliminate redundant most of the intermediate buffer
allocations we were performing for what should be zero-cost
conversions. This may slightly improve performance in some
cases.
* Correcting optimal LISPSM parameter.
* Figure shadows are cast when they're not visible.
* Chunk shadows stay cast until you look away.
* Seamless cubemaps for point lights.
* Etc.
