thejayman77
ba74bbd5aa
Per-vertex GS fog end-to-end (gs_stub emit incl. persp_emit5, gs_prim_list_feeder XYZ2->XYZF2 on PRIM.FGE, gs_make_sh3_scheduler_fixture.py F/FGE packing), new fog TBs, fidelity attribution tooling. Functional baseline before removing the dead bilinear lerp8 clamps (Codex: 161-node comb loop -> -0.042ns setup fail). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
64 lines
2.9 KiB
Markdown
64 lines
2.9 KiB
Markdown
# Ch426 — authentic vertex-alpha repair and atmospheric composite
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## Root cause
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The scheduler generator's `--auth-color-tfx` path preserved captured RGB but
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called `bake.rgbaq_with_q()`, a legacy helper that always writes alpha
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`0xff`. The first captured alpha fan actually uses vertex alpha `0x03` at
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the anchor and `0x00` at the remaining vertices. Under MODULATE+TCC, forcing
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that alpha to `0xff` made the authentic additive blend roughly two orders of
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magnitude stronger and produced Ch425's white rectangles.
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`gs_make_sh3_scheduler_fixture.py` now packs the complete captured 32-bit
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RGBA word when authentic color is enabled. It also fails closed if emitted
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RGBAQ alpha differs from the canonicalized source vertex. Legacy fixtures
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without authentic color retain their old opaque-alpha behavior.
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## Repaired fixture
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`zsrt139f22` regenerates the same 53 visible PSMT8 fan draws used by Ch405,
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in three exact-state groups, with:
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- captured RGBAQ alpha;
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- native GS 12.4 screen coordinates;
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- parsed kick semantics, authentic scissor, and framebuffer clipping;
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- authentic Z/TEST/ZMSK and ALPHA state;
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- runtime CLUT, MODULATE color, and production bilinear sampling.
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The repaired geometry expands to 218 one-triangle bounded epochs. The final
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chronological candidate `zsrt139f23` is Ch424's 125 epochs followed by the 20
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authentic CT32 darken epochs and the 218 repaired alpha epochs: 363 total.
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The rejected PSMT4 pass is not included.
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## Production RTL acceptance
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The complete replay passed:
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- 1,009,406 fragments fed; 990,062 passed;
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- 363 markers, zero fragment drops, zero color overflows, zero AXI errors;
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- Z mismatch 0/307,200 and color mismatch 0/245,314;
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- framebuffer SHA-256
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`ccf574d7e7ab06a519488c187da08b8c56dce5b923b6909dafba11cad6b4ce4a`.
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Against the PCSX2 frame, the accepted display mapping measures MAE 20.0713 /
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RMSE 28.9639, improving on Ch424's 20.9469 / 29.7626. The new image adds a
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soft captured atmospheric veil without the false white rectangles.
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A controlled no-darken replay (`zsrt139f24`, Ch424 + repaired alpha) also
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passed exactly but measured 20.0890 / 29.0439. The chronological CT32 pass
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therefore provides a small measured improvement as well as preserving the
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captured order; `zsrt139f23` remains the accepted candidate.
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## Silicon acceptance
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No new Quartus compile was needed. The timing-clean Ch423 RBF
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(`17d1c1b49aac4d893ed56285cf0703bf375db2ee9f472ea36862cca376ae63fe`)
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ran all 363 epochs on the DE25. Every texture CRC, palette checksum, staged
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record count, ordered drain, and zero-drop gate passed; the host returned
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`rc=0` and enabled the HDMI line-buffer source.
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The board dumped all 307,200 words with 196,889 nonzero pixels, bounds
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`(0,0)..(511,479)`, sum32 `0xb59376d4`, and xor32 `0x28c61f44`. Board and RTL
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framebuffer dumps are byte-identical and share the SHA-256 above. Ch426 is
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accepted on silicon and is the current live HDMI baseline.
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