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>
81 lines
3.8 KiB
Markdown
81 lines
3.8 KiB
Markdown
# Ch434 — current-frame light-buffer reconstruction
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## Fidelity gap
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Ch433's accepted `zsrt139f44` frame used the captured contents of TBP 11264
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for the two late full-screen darkening sprites. That texture was stale GS
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local memory rather than the intermediate produced by the current frame.
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The result retained recognizable scene structure, but its lighting was not
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chronologically connected to the scene being rendered.
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The omitted current-frame chain is:
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1. a PSMCT16S light target at FBP 256/TBP 8192, built by a clear, 2,053
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untextured Z-tested additive/subtractive volume draws, and a final bias
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sprite;
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2. conversion to the CT32 target at FBP 320/TBP 10240;
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3. three CT32 ping-pong sprites through FBP 352/TBP 11264 and FBP 320;
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4. the authentic draws 196167 and 196177, which sample the final TBP 11264
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image and blend it across the display.
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Ch434 reconstructs this chain as ordered static fixtures. The PSMCT16S
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target is rendered with the accepted scene Z, decoded to linear CT32, and
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then passed through the captured CT32 sprite states before the two display
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composites. This is a static fidelity bridge; animated render-to-texture
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still requires native target residency and ping-pong ownership in RTL.
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## Triangle-record topology repair
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The first integrated attempt exposed a fixture-contract bug. The scheduler
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generator expanded captured TRI_STRIP, TRI_FAN, and SPRITE topology into
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independent three-vertex records, while preserving the captured PRIM type in
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the feeder header. Because the feeder reissues PRIM for every record, a
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SPRITE record was assembled as a two-vertex sprite plus a dangling vertex,
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and strip/fan records restarted with the wrong topology.
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`tools/gs_make_sh3_scheduler_fixture.py` now advertises TRIANGLE for every
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expanded three-vertex record while preserving authentic TME, ABE, FST, and
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CTXT state. This changed the broken all-white ping-pong result into a stable
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binary light mask that retains the booth and character geometry through all
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three copies.
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## Rejected diagnostics
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- `zsrt139f46` painted the untextured volume family directly into the display.
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It was useful for isolation but architecturally wrong because the family
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targets PSMCT16S off-screen storage. It was never deployed.
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- `zsrt139f48` used the reconstructed chain before the triangle-record repair.
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It passed the internal RTL scoreboard but collapsed the intermediate to
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white and over-darkened the display. Its mapped PCSX2 score was
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MAE/RMSE 19.4763/29.3660, so it was rejected and never deployed.
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## Accepted result
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`zsrt139f49` combines the accepted Ch433 scene, the topology-correct
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current-frame light composite, and the existing textured-alpha tail. The
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production registered-gradient simulation passed all 311 epochs:
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- 2,339,914 fragments fed and 2,286,292 passed;
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- zero fragment drops, color overflows, and AXI errors;
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- 311 complete markers and drains;
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- zero final Z and color scoreboard mismatches.
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Against the PCSX2 frame through the accepted display map, f49 scores
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MAE/RMSE 14.1067/21.3468. This improves both metrics from f44's
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14.8127/21.5567, with a 0.7060 MAE reduction.
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No compile was required. The timing-clean Ch432 RBF ran the new assets on
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the Terasic board. All 311 runtime texture, palette, staging, drain, and
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zero-drop gates passed. The host reported 244,981 nonzero words, bounds
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`(0,0)..(511,479)`, sum32 `0x385dc4f6`, xor32 `0x6330653c`, and selected HDMI
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line-buffer source 1.
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The 307,200-word board framebuffer is byte-identical to production
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simulation at SHA-256
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`adb21828465758b0601956abef39b649f1f441a0a51831f90826ae76936f6606`.
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The accepted board image is
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`captures/gs/silenthill3/extracted/sh3_zsrt139f49_ch434_board.png`; its mapped
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comparison is
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`captures/gs/silenthill3/extracted/recon/sh3_zsrt139f49_ch434_board_mapped.png`.
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Ch434 is accepted, and f49 is the current live HDMI baseline.
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