Two changes, one measurement. The V6m smoke pair put GL versus Vulkan at
Holtburg at 18.52% of the frame differing at tolerance 2 with MSAA off. The same
stop on the same instrument now measures 9.05%, and the two populations these
address are gone from the difference map rather than merely smaller.
1. THE WORLD ATLASES WERE SAMPLED WITHOUT ANISOTROPY ON VULKAN, AND WITH THE
DEVICE MAXIMUM ON GL.
RhiWorldTextureArray -- the backend-neutral shared object/material atlas, and
the only IWorldTextureArray the Vulkan arm ever constructs -- registered its
clamp and repeat slots with GpuSamplerDescription.WorldClamp/WorldRepeat as
written, which carry MaxAnisotropy 1. The GL arm asks for the driver's own
GL_MAX_TEXTURE_MAX_ANISOTROPY twice over: ManagedGLTextureArray sets
GL_TEXTURE_MAX_ANISOTROPY on the image, and the two sampler objects its resident
bindless handles are built from (OpenGLGraphicsDevice.WrapSampler/ClampSampler)
set it again, which is the one that actually wins.
V6i-2 knew it was asking for 1 and said so in a comment -- "the world arm that
draws through these arrays is the next slice, and it is the one that can gate a
filtering change visually." That slice was V6j, the gate is V7, and this is it.
Retail settles the question rather than the GL arm settling it.
RenderDeviceD3D::SetDefaultD3DStates (0x005a3800) loops all sixteen sampler
stages and issues SetSamplerState(stage, 0xA, this->m_D3DCaps.MaxAnisotropy) at
0x005a4230. 0xA is D3DSAMP_MAXANISOTROPY and the argument is the device's
reported cap, not a setting -- so "as much anisotropy as this device has" is
retail's own rule, the GL arm is faithful to it, and asking for 1 diverged from
retail as well as from the shipping backend. No divergence-register row is owed
in either direction: this retires a Vulkan-only gap and lands on retail's value.
The fix asks for a ceiling rather than reading a limit back, because the pinned
RHI contract (plan section 3.3) carries no anisotropy field and is frozen. It
does not need one: VulkanGpuSampler already clamps MaxAnisotropy to
VkPhysicalDeviceLimits.maxSamplerAnisotropy, Vulkan guarantees that limit is at
least 16 wherever the samplerAnisotropy feature is supported -- which this
backend requires -- and 16 is where every desktop driver caps. The request and
the GL arm's read therefore land on the same number.
What it was worth, from the difference map at the same stop: the roof shingles
of both Holtburg cottages, which had been dense hatching across the whole
surface, and the stone courses of the near building are now black. Measured as
high-frequency energy (mean absolute neighbour difference, GL versus Vulkan) the
right-hand roof went from visibly blurred to a ratio of 0.999 and the wall to
1.023; every other textured region in the frame is between 0.99 and 1.02.
Grazing-angle surfaces are where anisotropy is the whole difference, which is
why a roof was the loudest thing in the frame.
2. THE SKY HAS TWO CLOCKS AND ONLY ONE OF THEM WAS PINNABLE.
ACDREAM_DAY_GROUP and the route's AcdreamCycleTimeOfDay presses pin the Dereth
date, which chooses the day group, the keyframe and the sun angle. The cloud
sheet does not read that clock: SkyRenderer accumulates TexVelocityX/Y against
DateTime.UtcNow minus its own construction time, by design, because retail's
clouds drift with real time regardless of the date. Two launches minutes apart
therefore cannot agree about where the clouds are no matter what the route does,
and the V6m smoke measured the cost -- 89% of its 18.52% sat in the top 240 rows.
ACDREAM_SKY_PHASE_SECONDS (RuntimeOptions.SkyAnimationPhaseSeconds ->
SkyRenderer.AnimationPhaseSecondsOverride) replaces that elapsed-seconds value
with a fixed one. Unset -- the default, and every ordinary run -- keeps the wall
clock, so nothing a user or the offline gate sees changes. The differential gate
forces it on both launches alongside MSAA and the day group; the offline gate
keeps its top-280 mask, because a same-commit GL pair still has the sun to
disagree about.
This is instrument determinism on the same footing as ACDREAM_DAY_GROUP, not a
workaround: it is one input to a UV offset, it is off by default, and no shipping
path reads it. The alternative on the table was -MaskTopPixels, which would have
permanently blinded the campaign's strictest instrument to the entire sky -- one
of the five surfaces the offline gate already cannot see. Rows 0-32 of the
Holtburg pair went from 23,090 differing pixels to 1,211, and what remains up
there is roof and portal rather than cloud.
WHAT THE SAME PAIR STILL SHOWS, unattributed and carried to the next commit: the
distant treeline, the player and the NPCs, and the animated portal. The portal is
phase and expected. The treeline is not filtering -- sharpness now matches within
5% and a shift search finds no sub-pixel offset -- and the two runs entered the
world at different last-logout positions (0xC95B0001 versus 0x09040008), so the
far-tier streaming history differed. That is the next thing to prove or refute.
Gates. Release build green. App tests 4,133 passed / 3 skipped against the
4,132/3 baseline (one new: the sky-phase parse). GL offline pixel gate against
the pre-change tree: 2.31e-05, 13 pixels of 563,200, inside the documented 9-31
band -- GL did not move. One offline Vulkan run with VK_LAYER_KHRONOS_validation
proven inserted by the loader: zero validation errors, zero warnings. Full
three-stop differential recorded at artifacts/v7-diff-c1.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Plan §5.5.11 recorded what V4t deliberately left behind: it moved the table
ENTRY of every world texture to the device and kept CREATION with the caches,
because "creating world textures through IGpuTexture is real remaining work and
it belongs with the Vulkan world arm, which is the first thing that cannot use a
GL handle at all." §5.5.12 item 1 handed it forward and named the missing piece
exactly — "an ITextureArray implementation over IGpuTexture, not a codec",
because V6b's BlockCompressionCodec and BlockCompressionMipChain already supply
the BC chains. This is that work.
IWorldTextureArray is the seam, and the slot is what crosses it. Before this
commit ObjectMeshManager read BindlessWrapHandle/BindlessClampHandle off the
concrete GL array and interned them into the device table itself. A 64-bit
ARB_bindless_texture handle has no Vulkan spelling, so the array now answers the
question the caller was really asking — ResolveSlot(wrapping) — and each arm gets
there its own way: ManagedGLTextureArray makes the same idempotent interning call
one level down, and RhiWorldTextureArray returns a pair it registered at
construction. ReleaseTextureSlots replaces the snapshot dictionary the manager
kept for the same reason, and still runs only once physical retirement completes.
Which implementation exists is decided ONCE, by the IWorldTextureArrayFactory
composition builds — plan §3.1's no-runtime-fork rule. Everything above the seam
(capacity policy, slot allocation, ref counting, layer retirement, empty-atlas
eviction, and the whole of ObjectMeshManager's atlas policy) is written once and
branches on nothing.
Three things the RHI array does differently, each because the backends genuinely
differ rather than by choice: BC mip chains are CPU-built through
BlockCompressionMipChain, since Vulkan cannot blit into a compressed image, while
RGBA8 uses the device's blit; filtering lives in an immutable sampler rather than
a texture parameter, so both address modes are registered up front exactly as the
GL array holds two resident handles; and RGB8/A8/Rgba32f are refused at creation
with the reason named. A8 is the interesting refusal — the GL array serves it by
swizzling R into A, and a Vulkan swizzle lives in the image VIEW, which the pinned
GpuTextureDescription does not describe. A silent substitution would render wrong
and look like a shader bug.
TerrainAtlas gains the second construction path V6i drafted and reverted. The
decode is factored out and shared, so both arms read the same DATs, in the same
order, with the same resize-to-max policy; only the upload forks.
ICompositeTextureArrayBackend gains its RHI arm, which is four small methods
because that seam was already a seam.
The Vulkan arm is EXERCISED, not merely present. That is the whole reason the
V6i draft was reverted rather than landed — "built then reverted because nothing
exercised it" — and it is the same failure §5.5.12 measured twice in the
descriptor layouts. So the composition host now builds the real terrain atlas
through IGpuDevice.CreateTexture on the arm with no GL context, and creates and
releases one shared array of each format family plus one composite array at
startup. Creation only; nothing draws them. Releasing them in the same statement
covers one thing a retained bundle would not — that both slot pairs come back and
the images route through the retirement queue.
Gates: Release build; App tests 4,104 / 3 skips; strict GL offline pixel gate vs
0ca802cd 3.20e-05 (18 px of 563,200, inside the documented 9–31 px control band);
GL connected tools/run-repeat-connected-gate.ps1 -Runs 3 at 3/3 RENDERED on the
desktop witness AND 3/3 on the client capture; one Vulkan composition-host run
with VK_LAYER_KHRONOS_validation proven inserted by the loader at zero errors,
zero warnings, no [shutdown] diagnostic, and a captured frame. That run built
terrain-atlas 512x512x33 with 10 mip levels, terrain-alpha-atlas 512x512x8, RGBA8
64x64x32 (slots 3/4, 174,720 mip bytes blitted), BC1 64x64x32 (slots 5/6, 696 mip
bytes encoded) and composite 32x32x8 (slot 7).
One whole-suite run failed Issue181WallPressEquilibriumTests once; it passed
alone and did not recur in five further runs. Seven test classes mutate the same
process-global CameraDiagnostics switches with no xUnit collection isolation, and
this diff touches no camera, visibility or physics code. A separate run of the
UNCHANGED parent tree failed a different zero-allocation test, which is `#250`'s
documented class. Both are filed rather than attributed.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Erik