BTDPL.INI's fog values for this mission (testarn.egg = arena1/day/clear,
[ardayclear] leaf: fog=200.0 1250.0 0.32 0.3 0.5, clip=0.25 1300.0) are exact,
verified ground truth. The depth term took two tries: `tz` (texz) looked like
the right candidate (BT411 says fog is linear on "W") but measured live it
DECREASES with distance -- the wrong direction/shape. Re-derived from the
actual firmware source instead of guessing again: AS860/XFPROJ.SS's own
comment on the projection code ("pz=wz*invz, where pz=1 at near clip, 0 at
infinity") establishes the z-buffer value as a normalized hither/distance
quantity, giving distance = hither * 2^20 / raw_zbuf_value.
gpu_raster.py: added a 10th shader output channel carrying the raw z-buffer
float (previously only a filled/empty flag existed), and the fog blend using
this formula + BTDPL.INI's exact color. Verified offline: distance climbs
smoothly (394->1051) across a receding ceiling, landing inside the authored
200-1250 range with no further fudging; visually the horizon shows the
authored blue-purple haze, correctly absent near the camera.
IG-SHADING-MODEL.md: documented the false start (tz) and the source-grounded
fix, with the honest caveats that remain (2^20 exact scale, hither as a fixed
per-mission constant vs. per-view from the wire).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Extends the existing shading-model reference (already the established pattern
for this cross-check) with tonight's live-pod findings, explicitly framed for
the BT411 modernization team's consumption per the user's stated purpose for
this whole pipeline: a hardware-grounded source of truth where the software
renderer has open or hard-to-fix questions.
Added: a cross-reference index into BT411's context/ docs (rendering.md,
open-questions.md, combat-damage.md); the lit-color-plane finding (real
mechanism, confirmed values, wrong when used as a texture tint -- reverted
same session); fog (BT411's complete model, not yet ported here); and honest
open/uninvestigated status for HUD, weapon-fire rendering, and cockpit-cage,
each pointing at where BT411 has probably already solved the adjacent
question so it isn't re-derived from scratch.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
These changes were made and verified earlier this session (the all-cyan bug
fix is already recorded as SOLVED in project memory) but never got committed --
render_final.py has referenced dpl_sampler as a module in its docstring since
ac4142e7, yet dpl_sampler.py itself was never added, leaving the repo unable
to run the M4b/M4c/M4d renderer scripts that all import it.
texstore.py: fix the texel word format. SVT texels are [pad,B,G,R] (ground
truth: dpl3-revive patha/vrboard.py do_texels + stage_assets.py); reading RGB
as bytes (0,1,2)=(pad,B,G) zeroed red, producing the all-cyan render. Correct
read is bytes (3,2,1).
dpl_sampler.py: the authentic IG-board texture-value model (wrap repeat/clamp,
near-black CUT keying) factored into its own tested module, distilled from the
shipped libDPL headers -- see IG-SHADING-MODEL.md (also added, referenced by
render_final.py's docstring but likewise never committed).
igc_exec.py: OP48/OP49 candidate opcodes (pixel global-X/Y seed into mem) added
to the CPU golden-model executor alongside the existing SCMEMA seed handling.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
CydandClaude Opus 4.8