Campaign V slice V6e, second of three. Billboard particles and mesh particles
are the last two pairs blocked on the texture-table shape; sky follows.
particle takes the same treatment mesh_modern took: the `flat uvec2` handle
varying becomes a `flat uint` slot and the fragment stage samples through
ACDREAM_SAMPLE_ARRAY. What is different here is the untextured particle. The
shader used to ask "is the handle I was given zero", which GL can answer because
its emulated table stores handles; Vulkan cannot, because set 2 is an opaque
descriptor array and reading an element nobody wrote is undefined rather than
zero. So the question moves to the index: the CPU writes ACDREAM_TEXTURE_NONE
for a particle with no texture instead of interning the null handle as a table
slot, and both dialects test the same value. GL renders identically — the same
particles take the same branch to the same procedural blob — and the handle
table simply stops carrying an entry that never named a texture. A test pins the
sentinel across all three declarations of it, because a silent disagreement here
would sample slot 0xFFFFFFFF instead of drawing the blob.
particle_mesh needed no restructuring, only names. Vulkan GLSL has no default
uniform block, so `uniform uint uTextureIndex;` is not unsupported but
unspellable, and the two values are per-pass — one texture and one layer for a
whole sub-batch — which is exactly what the shared push-constant block is for.
uTextureIndex becomes uTextureIndexA; uTextureLayer becomes uParamA, which was
the spare scalar and is a natural fit because the shader converted the layer to
float anyway. The widening moved from the shader to the CPU; layers are small
integers, so the sampled value is bit-identical.
Gates: Release build clean; App tests 4,058 passed / 3 skipped (baseline 4,057
plus the sentinel drift guard). Offline pixel gate against 95f8c25f: two
captures, 29 px and 21 px of 563,200 compared (3.73e-05 and 5.15e-05), with a
same-commit control between them of 13 px and this commit measuring 14 px
against its own parent. The scene draws no particles, so this gate is a tripwire
that the world path is undisturbed, not evidence about particles.
Particles remain user-gate debt — the same debt V2c and V4e already carry, to be
paid by casting a spell in a connected session.
Manifest: 6/9 pairs compile. Remaining: mesh (legacy, no consumer), sky (next
commit), terrain_modern.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Completes Campaign V slice V2 by moving both particle render paths -
billboard (particle.vert/.frag) and mesh-emitter (particle_mesh.vert/.frag) -
from raw 64-bit ARB_bindless_texture handles to binding=9 handle-table
indices, matching V2a's mesh path and V2b's terrain path.
Particles differ from both prior sub-slices in HOW the handle reaches the
shader:
- Billboard particles carry it as a per-INSTANCE vertex attribute (not an
SSBO batch or a per-draw uniform), because each particle can use a
different texture within one instanced draw. aTextureHandle (location 6,
uvec2) became aTextureIndex (uint); particle.vert looks it up via
ACDREAM_TEXTURE_HANDLE and reconstructs the SAME uvec2 into vTextureHandle
exactly as before, so particle.frag - including its zero-handle check for
the procedural circle fallback - needed no change at all. The per-instance
ABI struct BillboardGpuInstance shrank by 4 bytes (one uint slot instead of
two uint handle halves); ParticleBindlessInstanceTests updated for the new
68-byte layout and the vertex attribute declaration text.
- Mesh-emitter particles carry it as a per-draw uniform (uTextureHandle,
uvec2) exactly like terrain's pattern from V2b: one texture per draw call,
set right before it. Became uTextureIndex (uint) + the same
ACDREAM_TEXTURE_HANDLE lookup.
ParticleRenderer owns its own GlBindlessHandleTable and binding=9 SSBO,
independent of the other three renderers' tables, created eagerly in the
constructor alongside the other GL resources it already creates there. Unlike
the other three renderers, flushing/binding the table happens immediately
before EVERY individual draw call (four call sites: immediate billboard,
immediate mesh, and both halves of the deferred/prepared RetailAlphaQueue
path) rather than once per pipeline-state switch - a run of consecutive
mesh-particle sub-batches can register a new handle partway through (each
sub-batch has its own texture), and the table must be current for each one,
not just the first.
TextureCache's particle-texture cache (AcquireParticleTexture,
StandaloneBindlessTextureCache) needed no change: it only ever hands back a
raw ulong handle, and both ParticleGfxInfo.TextureHandle and
ParticleInstance.TextureHandle keep carrying that raw value - the table
lookup is added exactly where each path already converts its handle into
GPU-visible state (WriteBillboardGpuInstance and the two ProgramUniform
call sites).
Coverage caveat (flagged per the campaign doc's slice table): the offline
pixel gate's fixed outdoor view has no particles in frame, so it does not
exercise this slice - it only confirms nothing else regressed. This change
is correspondingly kept strictly mechanical (indirection only, no logic
change), but it still needs a user visual check with live particle emitters
before being trusted as pixel-identical.
Gate: dotnet build -c Release green, dotnet test tests/AcDream.App.Tests
-c Release green (3843 passed / 3 skipped on a clean run - one unrelated
pre-existing flaky allocation test, UiDatFontTests, failed once and passed
on immediate re-run in isolation and in the full suite, confirmed unrelated
to this change), and tools/run-offline-pixel-gate.ps1 passed against the
V2b commit's build with a 4.62e-05 differing-pixel fraction (a tripwire
only, per the coverage caveat above). No divergence-register row: this
introduces no retail behavior deviation.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Carry each billboard particle's resident texture handle in the instance ABI so stable retail alpha ordering can batch mixed textures without rebinding and redrawing each short texture run. Keep DAT blend transitions as the only billboard draw boundary.
The connected 0xC95B stress scene improved from 6 FPS / 171 ms to about 153 FPS / 6.6 ms at the same roughly 21,000 visible entities. Release build succeeds and all 5,916 tests pass with five intentional skips.
Co-authored-by: OpenAI Codex <codex@openai.com>
