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[GPU] 8-bit PWL gamma RT as linear 16-bit UNorm on the host

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With render target HLE, directly store linear values as R16G16B16A16_UNORM
without gamma conversion, as this format provides more than enough bits
(need at least 11 per component due to the maximum scale being 2^3 in the
piecewise linear gamma curve) to represent linear values without precision
loss.

This makes blending work correctly in linear space, improving quality of
transparency, lighting passes, and fixing issues such as transparent parts
of impact and footstep decals in 4D5307E6 being bright instead.

The new behavior is enabled by default, as it hugely improves the accuracy
of emulation of this format, that is pretty commonplace in Xbox 360 games,
with likely just a small GPU memory and bandwidth usage increase, compared
to the alternatives that were previously available on the HLE RB path.

It's currently implemented only on Direct3D 12, as most of the current GPU
emulation code is planned to be phased out and redone, and no methods other
than 8-bit with pre-conversion were implemented on Vulkan previously.

To implement on Vulkan later, same conversion as in the Direct3D 12
implementation will need to be done in ownership transfer and resolve
shaders. Currently it's somewhat inconvenient to decouple the conversion
functions in `SpirvShaderTranslator` from an instance of the translator due
to vector constant usage. Later, simpler SPIR-V generation functions may be
added (`spv::Builder` usage in general is overly verbose).

The previously default method (8-bit storage with pre-conversion in shaders
and incorrect blending) can be re-enabled by setting the
"gamma_render_target_as_unorm16" configuration option to `false`. This may
be useful if the game, for instance, switches between 8_8_8_8_GAMMA and
8_8_8_8 formats for the same data frequently, as switching will result in
EDRAM range ownership transfer data copying now. Also, the old path is
preserved for Vulkan devices not supporting R16G16B16A16_UNORM with
blending.

The other workaround that was available previously, replacing the PWL
encoding with host hardware sRGB with linear-space blending in render
target management and in texture fetching, was also inherently inaccurate
in many ways (especially when games have their own PWL encoding math, like
4541080F that displayed incorrect colors on the loading screen), and
required tracking of the encoding needed for ranges in the memory.

The sRGB workaround therefore was deleted in this commit, greatly
simplifying the code in the parts of render target, texture and memory
management and shader generation that were involved in it.
This commit is contained in:
Triang3l
2026-01-17 18:09:42 +03:00
parent f2fabfdf04
commit cec9ca0ef2
34 changed files with 3072 additions and 3188 deletions
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26
src/xenia/gpu/texture_cache.h
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@@ -110,14 +110,15 @@ class TextureCache {
GetValidTextureBinding(fetch_constant_index);
return binding ? binding->swizzled_signs : kSwizzledSignsUnsigned;
}
bool IsActiveTextureResolved(uint32_t fetch_constant_index) const {
bool IsActiveTextureResolutionScaled(uint32_t fetch_constant_index) const {
const TextureBinding* binding =
GetValidTextureBinding(fetch_constant_index);
if (!binding) {
return false;
}
return (binding->texture && binding->texture->IsResolved()) ||
(binding->texture_signed && binding->texture_signed->IsResolved());
return (binding->texture && binding->texture->key().scaled_resolve) ||
(binding->texture_signed &&
binding->texture_signed->key().scaled_resolve);
}
protected:
@@ -218,18 +219,6 @@ class TextureCache {
}
uint64_t last_usage_time() const { return last_usage_time_; }
bool GetBaseResolved() const { return base_resolved_; }
void SetBaseResolved(bool base_resolved) {
assert_false(!base_resolved && key().scaled_resolve);
base_resolved_ = base_resolved;
}
bool GetMipsResolved() const { return mips_resolved_; }
void SetMipsResolved(bool mips_resolved) {
assert_false(!mips_resolved && key().scaled_resolve);
mips_resolved_ = mips_resolved;
}
bool IsResolved() const { return base_resolved_ || mips_resolved_; }
bool base_outdated(
const std::unique_lock<std::recursive_mutex>& global_lock) const {
return base_outdated_;
@@ -275,13 +264,6 @@ class TextureCache {
Texture* used_previous_;
Texture* used_next_;
// Whether the most up-to-date base / mips contain pages with data from a
// resolve operation (rather than from the CPU or memexport), primarily for
// choosing between piecewise linear gamma and sRGB when the former is
// emulated with the latter.
bool base_resolved_;
bool mips_resolved_;
// These are to be accessed within the global critical region to synchronize
// with shared memory.
// Whether the recent base level data needs reloading from the memory.