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Glass cockpit lamps: sweep every frame so lit buttons track the sim under load

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Playtesters (all on the glass surround) reported the cockpit lighting
sometimes going slow or nonexistent while the 3D view stayed perfectly
smooth.  The RIO serial/lamp stack is byte-identical to pod-proven Red
Planet (diffed L4LAMP/L4RIO/L4SERIAL), so the wiring was fine -- the defect
is the glass UPDATE CADENCE:

The lit buttons draw every frame (BTDrawCockpitPanels, reading
PadRIO::GetLampState), but the lamp STATE sweep that fills that store
(LampManager::Update -> AssertNewLampValue -> SetLamp) rides the gauge
renderer's FOREGROUND turn, which fires only once per full gauge cycle
(foreground->background->copy).  The cycle can't reach the next foreground
turn until the throttled background gauge sweep drains the ~140-instrument
active list -- and that background task starves under MP load (issue #45,
"instruments freeze while fps stays healthy").  So the lamp sweep ran
~1x/second: buttons froze / flashes stalled while the view (a separate
per-frame foreground render) stayed smooth.

Fix: BTGlassSweepLamps() runs the lamp sweep EVERY frame on the dev/glass
composite path (L4VB16.cpp, in BTDrawGaugeInset), decoupled from the gauge
cycle.  It is cheap -- deduped state pushes over ~72 lamps, no raster.  The
pod never enters BTDrawGaugeInset (real gauge hardware), so its authentic
bandwidth-paced serial lamp cadence is untouched.  BT_GLASS_LAMP_SWEEP=0
restores the authentic once-per-cycle behaviour.

Verified: Release links clean (only the 40 tolerated /FORCE externals);
glass surround boots and runs, lamp sweep pushes state (43 [lamp] pushes,
buttons lit), ~60 fps, no crash.  The under-load win is structural (the
sweep is now an unconditional per-frame call); true MP-starvation repro
needs multiple nodes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
Cyd
2026-08-04 09:41:04 -05:00
co-authored by Claude Opus 4.8
parent 08ca66e5b5
commit f99003cf50
3 changed files with 60 additions and 1 deletions
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engine/MUNGA_L4/L4VB16.cpp
+44 -1
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@@ -1284,6 +1284,47 @@ void BTCockpitMouseUp(void)
}
}
//
// (glass lamp responsiveness, 2026-08) Sweep the cockpit lamp STATE every frame.
//
// The lamp sweep -- LampManager::Update -> AssertNewLampValue -> RIO/PadRIO::SetLamp,
// which is what lights the cockpit buttons -- authentically rides the gauge
// renderer's FOREGROUND turn (GaugeRenderer::ExecuteForeground, gaugrend.cpp), and
// that turn fires only ONCE PER FULL GAUGE CYCLE (foreground -> background -> copy).
// The cycle only advances to the next foreground turn after the THROTTLED background
// gauge sweep drains the whole active-instrument list -- and that background task
// starves under load (issue #45: "every cockpit instrument freezes at its last paint
// while the underlying values AND fps stay perfectly healthy"). So on a busy MP
// mission the lamp sweep ran ~1x/second: the lit buttons froze / flashes stalled while
// the 3D view (a separate per-frame foreground render) stayed smooth -- exactly the
// "lighting slow or nonexistent" playtest reports (all on glass desktops).
//
// The lamp sweep is CHEAP -- deduped state pushes over ~72 lamps, no raster -- so on
// the dev/glass composite path we run it EVERY frame here, decoupled from the gauge
// cycle, and the buttons track the sim regardless of background-sweep slack. The pod
// NEVER enters BTDrawGaugeInset (it drives real gauge hardware), so its authentic
// bandwidth-paced serial lamp cadence is untouched. BT_GLASS_LAMP_SWEEP=0 restores the
// authentic once-per-cycle behaviour.
//
static void
BTGlassSweepLamps()
{
static int s_on = -1;
if (s_on < 0)
{
const char *e = getenv("BT_GLASS_LAMP_SWEEP");
s_on = (e != NULL && e[0] == '0') ? 0 : 1;
}
if (!s_on) return;
GaugeRenderer *gr = BTResolveGaugeRenderer();
if (gr == NULL || application == NULL) return;
LampManager *lm = gr->GetLampManager();
ModeManager *mm = application->GetModeManager();
if (lm != NULL && mm != NULL)
lm->Update(mm->GetModeMask());
}
//
// Free entry point the MAIN renderer calls (L4VIDEO DPLRenderer::ExecuteImplementation,
// just before EndScene). No-op unless BT_DEV_GAUGES is set. Docks the 6-surface panel
@@ -1292,7 +1333,9 @@ void BTCockpitMouseUp(void)
//
void BTDrawGaugeInset(LPDIRECT3DDEVICE9 device)
{
if (!DevGaugeComposite() || !DevGaugeDocked() || device == NULL) return;
if (!DevGaugeComposite()) return;
BTGlassSweepLamps(); // keep the cockpit lamps tracking the sim EVERY frame (see above)
if (!DevGaugeDocked() || device == NULL) return;
if (GlassPanelsOwnSurfaces()) return; // the per-display glass windows draw the surfaces
if (gBTGaugeCockpit)
{