Two April stand-ins, neither registered, met at the horizon from altitude as
a hard line between the dome's rim and the fog-coloured clear:
1. sky.frag fogged every non-additive sky layer with a 0.2 floor. Retail's
GameSky::Draw @0x00506FF0 disables fixed-function fog around the whole
sky draw unless an AdminEnvirons fog override is active (SetFFFogEnable(
LScape::m_override_enabled ? 1 : 0)); additive layers stay unfogged via
SetFFFogAlphaDisabled(1) at D3DPolyRender::SetSurface 0x59c882. The sky
pass now sets ApplyFog only for (override active && !additive), with no
floor.
2. WorldRenderFrameBuilder overwrote the authored fog range with one derived
from the streaming window (538..2189 m always). Retail sets FOGSTART/
FOGEND straight from the keyframe's MinWorldFog/MaxWorldFog
(SkyDesc::GetWorldFog @0x00500CE0 -> SetFFFogProperties @0x005A2F70) with
no draw-distance scaling; zfar is a constant 4000 m. The builder now
leaves SceneLightingUbo.Build's values alone; ACDREAM_FOG_START_MULT /
_END_MULT are deleted from RuntimeOptions.
Guards: SkyFogRuleTests (source-level, the sky renderer has no hermetic
harness); sky.frag.spv re-pinned in VulkanShaderManifestTests with the
reason. Research note 2026-04-23-sky-fog.md carries a correction banner.
App hermetic 6,070/0, Core 4,707/0 (Release). Owner look gate owed: night
and rain fog are now retail's shorter authored ranges.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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