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perf(rendering): preserve alpha order with bindless particles

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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>
This commit is contained in:
Erik 2026-07-18 08:32:21 +02:00
parent 6b0472ee32
commit 2cbf34a668
7 changed files with 150 additions and 57 deletions
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13
docs/ISSUES.md
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@ -68,9 +68,22 @@ flush boundaries. It preserves DAT blend/cull/lighting state and batches only
adjacent compatible submissions so renderer grouping cannot change the
compositing order.
The first connected build exposed a modern-backend performance regression:
distance sorting naturally interleaves particle textures, while the old
billboard shader required one texture bind/draw for every texture run. After
several portals, the dense `0xC95B` scene reached roughly 21,000 visible
entities and fell to 6 FPS / 171 ms. This was not a retained queue or streaming
leak. Billboard instances now carry their resident bindless texture handle in
the vertex-instance ABI; different textures therefore remain in exact sorted
order inside one instanced draw, with only DAT blend-mode changes splitting a
run. The identical location recovered to about 153 FPS / 6.6 ms in the
connected Release client.
**Files:** `src/AcDream.App/Rendering/RetailAlphaQueue.cs`;
`src/AcDream.App/Rendering/Wb/WbDrawDispatcher.cs`;
`src/AcDream.App/Rendering/ParticleRenderer.cs`;
`src/AcDream.App/Rendering/Shaders/particle.vert`;
`src/AcDream.App/Rendering/Shaders/particle.frag`;
`src/AcDream.App/Rendering/RetailPViewRenderer.cs`.
**Research:**

4
docs/architecture/worldbuilder-inventory.md
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@ -138,6 +138,10 @@ acdream-owned runtime seam above the extracted mesh pipeline. During the main
world frame, `WbDrawDispatcher` and `ParticleRenderer` submit transparent
GfxObj subsets and scene particles into one stable far-to-near stream keyed by
the transformed DAT `SortCenter`; only adjacent compatible entries may batch.
Billboard particle textures are resident bindless `sampler2DArray` handles in
the per-instance vertex ABI, so different textures preserve that sorted order
inside one instanced draw; only a DAT blend-mode boundary splits the run. This
keeps dense particle fields from becoming one GL draw per alternating texture.
`RetailPViewRenderer` drains the landscape scope before the optional depth
clear, and `GameWindow` drains the final scope before private viewports/UI.
Sky and sealed off-screen render targets remain independent. No DAT reader,

5
docs/research/2026-07-18-retail-shared-alpha-list-pseudocode.md
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@ -177,7 +177,10 @@ The named retail client remains the behavioral oracle.
retaining retail's missing per-`CPartCell` lists. AP-34 records that narrow
architectural residual explicitly.
4. The queue itself does not reorder by renderer or material. Only adjacent
compatible submissions may batch.
compatible submissions may batch. The modern billboard vertex-instance
record carries a bindless texture handle, so adjacent particles with
different textures are still one compatible ordered draw; blend mode is
the only billboard state boundary.
5. Every flush keeps depth testing enabled and depth writes disabled.
6. Each submission preserves its DAT blend mode, cull mode, transform,
texture, lighting, opacity, and selection-lighting state.