GE's texLoadFromGdl picks a handler per G_NOOP texture reference from w0 & 7.
TEXTURETYPE_LOD/MIPMAP (texHandleType0/Type2) issue ONE load block at TMEM 0,
so tiles 0..n are LOD levels of that one image. TEXTURETYPE_DETAIL
(texHandleType1, src/game/tex.c) issues TWO: the detail texture at TMEM 0 and
the real base image at TMEM texGetSizeInBytes(detail,0) on tiles 1+.
gfx_lod_tile_offset folded every G_TL_LOD draw to tile 0 (D107 -- correct for
the first two, wrong for DETAIL), so the port drew the detail texture and never
imported the base image at all. All four Surface 1 treeline cards
(tex1198-tex1201, RGBA5551 64x17 cut-outs) are DETAIL bindings sharing one
detail texture, tex2465: an opaque 32x32 IA8 noise tile. That is the same
texture D267/D276 measured at 1023/1024 texels opaque and called the mystery
"noise painter" -- hence 20+ passes chasing decode, alpha, mip and geometry
theories for what was a binding bug.
Fix (port layer only): under G_TL_LOD, if tile fi+1 differs from tile fi in
BOTH TMEM address and fmt/siz, sample tile 1. Asymmetric on purpose -- LOD
levels of one image always share a format, so a mip chain can never trip it,
and a detail pair that happened to share a format just keeps the old
behaviour. Config Video.DetailBaseTile, default on.
Verified: Surface 1 idle spawn goes from an opaque tiled noise wall to discrete
snow-covered pines with ground/snow unchanged; Surface 2 shows a discrete night
treeline; Depot renders clean; bunker1 golden framediff is bit-identical with
the fix on and off. Offline scan of every level's bg: DETAIL bindings exist
only in sevx (84), depo (39), sevb (4), sev (4), so every other level is
provably untouched. User play-test confirmed.
Also refuted and removed pass 25's fix direction: cut-out mip suppression
changed nothing, and its alpha census showed the wall is painted by a fully
opaque texture -- retiring the mip / 1-bit-alpha / XLU-smear branch. The
GE_D236P25 probe is gone with it.
tools_pc/gen_env_probes.py: stop counting a "GE_FOO[" log-line TAG in the doc
as a documented env var. GE_TEXDUMP_ADDR prints "GE_TEXA[...]", which is not
the name of any getenv(), so the check reported a permanent phantom GONE.
Generalised as docs/porting-notes.md D12; full trail in findings.md D236 pass
26. Carries the pending D75/M-197 sidecar-converter fix and the env-gated
D236/D75 probes, which the doc gates require to land alongside their rows.
