User-visible bug: connected the reconstructed renderer to the REAL running pod
for the first time (M4d demo) and the render fell increasingly behind the live
game, plus looked near-grayscale. Root-caused with direct profiling instead of
guessing:
1. VPX_RENDER=1 was set in launch_live.ps1 (copied from launch_pod.ps1's
defaults without thinking it through) -- it starts vpxlog.cpp's OWN native
GL render thread (rt_main), which contends with our renderer for the same
CPU/GL resources. Live-caught: with it set, wire delivery stalled at wire
command 8 for 90+s; removing it, the same mission reached command 21,488
in the same window. This was the dominant cause of the visible lag.
2. gpu_raster.build_prims() scanned the whole per-draw program window
(0x08158000-0x08170000, ~24k words) via a Python-level r32() call per word
every frame. Added emu860c.dump_range(lo,hi)->bytes (one bulk C read) and
rewrote build_prims to index a numpy array instead -- verified byte-identical
dump_range output first, then reconfirmed the whole render is STILL
bit-identical to the CPU reference (frames 0/5/11, differ>24 = 0.000%).
3. Profiling after (1) showed the per-texture compositing loop was the real
remaining cost: 62ms/frame doing full-832x512-frame fancy-indexed texture
sampling for EACH of 13 textures, regardless of how few pixels use each one.
Added dpl_sampler.composite_masked (sample+composite only the pixels a
texture actually covers; verified equivalent to composite() on a partial
mask in dpl_sampler's own conformance test) and hoisted the invariant
out of the loop.
Combined: render time 95.8ms -> 54.9ms/frame (~1.75x from this change alone,
~2.1x vs the original ~117ms/frame baseline), still bit-identical to the CPU
reference throughout.
launch_live.ps1: removed VPX_RENDER, renamed the automatic-variable shadow
-> (flagged by PSScriptAnalyzer), added -Pin <fifodump> to
pre-load the full texture set (bit-identical to offline) instead of the
incremental default, for a demo that wants correct color immediately rather
than waiting on the live mission's own upload order.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
CydandClaude Opus 4.8
ef7db9f2e4