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>
82 lines
3.8 KiB
Markdown
82 lines
3.8 KiB
Markdown
# Ch432 — perspective palette-bilinear handshake repair (prefit)
|
|
|
|
## Objective
|
|
|
|
Remove the regular missing-sample pattern from the authentic SH3 perspective
|
|
scene without changing its fixture, chronology, Z state, textures, palettes,
|
|
or accepted display mapping. The live f42 composition remains the input; this
|
|
chapter is an RTL fidelity repair and therefore requires a new owner GUI fit.
|
|
|
|
## Root cause
|
|
|
|
Dense perspective palette-bilinear epochs emitted almost exactly half of their
|
|
independent software coverage. Representative f19 epoch 74 emitted 7,301
|
|
fragments against 14,371 independently rasterized covered pixels. Other dense
|
|
epochs showed the same approximately 2:1 deficit. A GEQUAL-to-ALWAYS Z-only
|
|
diagnostic added just 571 lit pixels and worsened PCSX2 score, ruling out Z as
|
|
the broad missing-surface cause.
|
|
|
|
The serialized four-tap sampler launched an S1 pixel in `PB_IDLE`, held the
|
|
pipeline in `PB_WAIT`, emitted the completed pixel, and then advanced again in
|
|
`PB_RELEASE`. Because the launch cycle had already advanced the raster walker,
|
|
the release advance skipped the next waiting S1 sample. This produced the
|
|
regular screen-door population loss while all existing scoreboards still
|
|
passed for the subset that was actually emitted.
|
|
|
|
## RTL repair
|
|
|
|
The sampler now treats launch as the single normal pipeline advance, holds
|
|
through `PB_WAIT`, and uses `PB_RELEASE` as a final hold cycle. The next S1
|
|
sample is therefore launched rather than overwritten. Perspective input valid
|
|
is also qualified by the existing Z and texture-alpha advance enables, so a
|
|
frozen beat cannot submit the held sample twice.
|
|
|
|
This sequencing deliberately keeps the 35-bit triangle-inside result off the
|
|
high-fanout pipeline-enable path. The only added global gating term is the
|
|
already-registered two-bit sampler state, minimizing timing risk after the
|
|
timing-clean Ch431 baseline.
|
|
|
|
## Regression gates
|
|
|
|
The PSMT8 perspective triangle test now enables the serialized
|
|
palette-bilinear path and checks independent coverage. It passes 31/31 covered
|
|
samples with no missing pixels, valid colors, correct alpha metadata, and
|
|
correct MODULATE behavior. The affine palette-bilinear tile regression also
|
|
passes unchanged.
|
|
|
|
The production isolated epoch-74 gate is now explicit through
|
|
`+EXPECT_FED=14341`. It passes at 14,341 fragments (up from 7,301), with zero
|
|
drops, exact Z/color comparisons, and complete marker/drain accounting. The
|
|
30-pixel difference from the independent 14,371 coverage map is the existing
|
|
edge-rule/model boundary, not alternate-sample loss.
|
|
|
|
The complete unchanged f42 composition passes all 292 epochs:
|
|
|
|
- 2,339,405 fragments fed and 2,285,783 passed;
|
|
- 292 markers and drains;
|
|
- zero fragment drops, color overflows, and AXI errors;
|
|
- Z mismatch 0/307,200 and color mismatch 0/245,760;
|
|
- framebuffer SHA-256
|
|
`31d21fb5c38816ef99ace1d7b55186dc749720e874ecb055a68b21584ec27037`.
|
|
|
|
## Fidelity result
|
|
|
|
The repaired f19 opaque scene lights 173,354 pixels instead of 111,705. Its
|
|
error against the independent f19 software reference improves from MAE 11.7491
|
|
/ RMSE 24.6649 to MAE 8.7494 / RMSE 18.7008. Against the PCSX2 frame through
|
|
the accepted display map it improves from MAE 20.9469 / RMSE 29.7626 to MAE
|
|
18.3393 / RMSE 25.8374.
|
|
|
|
On the complete f42 composition, 240,224 pixels are nonzero. The mapped PCSX2
|
|
score improves materially from Ch431's MAE 18.9405 / RMSE 27.6301 to MAE
|
|
15.0765 / RMSE 21.9717. The remaining visual noise is real follow-on work, but
|
|
this chapter restores a large missing surface population rather than merely
|
|
adding more draw capacity.
|
|
|
|
## Fit boundary
|
|
|
|
The preceding owner GUI fit is clean and the runtime-fabric audit passes at
|
|
38,241 ALMs and 336 RAM blocks, with 310 MHz setup met. Those reports predate
|
|
this RTL repair. Ch432 is simulation-complete and ready for the owner to run a
|
|
new Quartus GUI compile; no command-line Quartus flow was used.
|