#1159 Weather: glass roofs keep the rain and snow out #1168

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TheSlowly wants to merge 1 commit from TheSlowly/Slipstream:weather-glass-roof-1159 into main

TheSlowly commented

2026-10-27 21:03:16 +00:00

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Fixes #1159 (a closed glass dome let rain and snow through).

Cause: the weather roof map drew alpha-blend casters with the shadow alpha test's 0.5 cutoff, so any glass below half opacity counted as open sky.

Change: the map's blend bucket uses its own pipeline (a specialization constant in clean_shadow_mask.frag) with a weather-only cutoff, RenderVKWeatherGlassAlphaCutoff (default 0.05, the same threshold as shadows and the avatar shelter maps). Glass roofs now shelter, while alpha-0 and near-invisible prims stay open. Alpha-mask foliage keeps its own cutoff, and the shadow passes are unchanged.

Tested in-world: a glass dome at alpha 0.26 keeps the floor under it dry; 0.5 brings the old behaviour back.

Fixes #1159 (a closed glass dome let rain and snow through). Cause: the weather roof map drew alpha-blend casters with the shadow alpha test's 0.5 cutoff, so any glass below half opacity counted as open sky. Change: the map's blend bucket uses its own pipeline (a specialization constant in `clean_shadow_mask.frag`) with a weather-only cutoff, `RenderVKWeatherGlassAlphaCutoff` (default 0.05, the same threshold as shadows and the avatar shelter maps). Glass roofs now shelter, while alpha-0 and near-invisible prims stay open. Alpha-mask foliage keeps its own cutoff, and the shadow passes are unchanged. Tested in-world: a glass dome at alpha 0.26 keeps the floor under it dry; 0.5 brings the old behaviour back.

TheSlowly added 1 commit

2026-10-27 21:03:17 +00:00

#1159 Weather: glass roofs keep the rain and snow out (a weather-only alpha-blend cutoff) a62017f95c

The weather occlusion map drew alpha-blend casters with the projector tiles' alpha test, which
cuts blend materials at 0.5: glass under half opaque (the observatory dome, PBR alpha 0.26) was
open sky for the rain streaks, the surface wetness and the snow cover.

The map's alpha-blend bucket now draws with mWeatherBlendPipe: mProjMaskDsPipe with the
alpha-test FS's weather twin (clean_shadow_mask.frag specialization constant 0). It tests a
blend caster's alpha (PBR base colour alpha or legacy transparency, x the texel's alpha) against
RenderVKWeatherGlassAlphaCutoff (default 0.05, about 95% transparency; floored at 1/255),
pushed in VKDrawViewPush::pad1. Alpha-mask materials keep their own cutoff. Every sun /
projector / cluster shadow pipeline specializes the constant false: their test is unchanged
and they never read the push. One extra pipeline (+ its depth-only VS twin) at init, nothing
per frame; while it compiles (or if it fails) the map falls back to the 0.5 test.

TheSlowly referenced this pull request

2026-10-27 21:35:03 +00:00

GPU hang (Xid 109) in the RT reflection trace (c_defer_rtrefl_trace) -- persists past ab53e12cc9 #1128

TheSlowly commented

2026-10-27 22:10:00 +00:00

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Merged into main (rebased) as dfb46dc975.

Merged into main (rebased) as dfb46dc975.

TheSlowly closed this pull request

2026-10-27 22:10:00 +00:00

TheSlowly referenced this pull request