This was added because YAGCD's info on MAXANISO (near TX_SETMODE0 in Section 5.11.1) claims it's the case, but Extrems says it does work. I haven't tested anything myself, and dolphin still does not actually implement anisotropic filtering based on this field.
Manually encoding and decoding logical immediates is error-prone.
Using ORRI2R and friends lets us avoid doing the work manually,
but in exchange, there is a runtime performance penalty. It's
probably rather small, but still, it would be nice if we could
let the compiler do the work at compile-time. And that's exactly
what this commit does, so now I have no excuse for trying to
manually write logical immediates anymore.
SPDX standardizes how source code conveys its copyright and licensing
information. See https://spdx.github.io/spdx-spec/1-rationale/ . SPDX
tags are adopted in many large projects, including things like the Linux
kernel.
This fixes bounding box shaders failing to compile under Vulkan, due to
differences between GLSL and HLSL in the return value of vector
comparisons and what types these functions accept. I included all() for
the sake of completeness.
At higher resolutions, our bounding box dimensions end up being
slightly larger than original hardware in some cases. This is not
necessarily wrong, it's just an artifact of rendering at a higher
resolution, due to bringing out detail that wouldn't have appeared on
original hardware. It causes a texel to fall partially on what would
have been a single pixel at native resolution, resulting in the
coordinates getting bumped up to the next valid value. In many cases,
these slightly larger bounding boxes are perfectly fine, as games don't
hard-code expected dimensions. It is problematic in Paper Mario TTYD
though, for a somewhat complicated reason.
Paper Mario TTYD frequently uses EFB copies to pre-render a bunch of
animation frames for a character sprite (especially in Chapter 2), so
that it can then render 100 or more of them without bringing the
GameCube to its knees. Based on my observation, the game seems to set
aside a region of memory to store these EFB copies. This region is
obviously fairly small, as the GameCube only has 24MB of RAM. There are
2 rooms in Chapter 2 where you fight a horde of as many as 100 Jabbies,
which are also rendered using EFB copies, so in this room the game ends
up making 130(!) EFB copies just for Puni and Jabbi sprites. This seems
to nearly fill the region of memory it set aside for them.
Unfortunately, our slightly larger bounding boxes at higher resolutions
results in overflowing this memory, causing very strange behavior. Some
EFB copies partially overlap game state, resulting in reading it as a
garbage RGB5A3 texture that constantly changes. Others apparently
somehow trigger a corner case in our persistent buffer mapping, causing
them to partially overwrite earlier EFB copies.
What this change does is only include the screen coordinates that align
with the equivalent native resolution pixel centers, which generally
results in the bounding boxes being more in line with original
hardware. It isn't perfect, but it's enough to fix Paper Mario TTYD's
Jabbi rooms by avoiding the buffer overflow. Notably, it is more
accurate at odd resolutions than at even resolutions. Native resolution
is completely unaffected by this change, as should be the case. This
change may also have a small positive impact on shader performance at
higher resolutions, as there will be less atomic operations performed.
Running the min/max operation on the upside down, quad-rounded pixel
coordinates before inverting them to the standard upper-left origin
produces wrong results. Therefore, we need to do the inversion before
rounding to pixel quads.
Fragment coordinates always have a 0.5 offset from a whole integer, as
that's where the pixel center is on modern GPUs. Therefore, we want to
always round the fragment coordinates down for bounding box
calculations. This also renders the pixel center offset useless, as 0.5
vs ~0.5833333 makes no difference when rounding down.
The SDK seems to write "default" bounding box values before every draw
(1023 0 1023 0 are the only values encountered so far, which happen to
be the extents allowed by the BP registers) to reset the registers for
comparison in the pixel engine, and presumably to detect whether GX has
updated the registers with real values. Handling these writes and
returning them on read when bounding box emulation is disabled or
unsupported, even without computing real values from rendering, seems
to prevent games from corrupting memory or crashing.
This obviously does not fix any effects that rely on bounding box
emulation, but having the game not clobber its own code/data or just
outright crash is a definite improvement.
This fixes rendering issues in Viewtiful Joe (https://bugs.dolphin-emu.org/issues/12525), but it is not entirely hardware accurate, as hardware testing showed other, more complex behavior in this case. However, it should be good enough for our purposes.
Pokechu22