Volumetrics P2: volumetric sky cloud layer (EEP-driven, configurable altitude, cloud shadows) #719

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opened 2026-10-12 13:15:16 +00:00 by sky_line · 1 comment

sky_line commented

2026-10-12 13:15:16 +00:00

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Part of #722 (volumetrics epic).

Raymarched cloud layer in a shell between two altitudes (Horizon Zero Dawn / Nubis / Frostbite style).

Shape: tiling 3D noise (128^3 base + 32^3 detail erosion) + a 2D weather map (coverage, cloud type, wind).
Lighting: Beer's law transmittance + powder term, dual Henyey-Greenstein phase (silver lining), multi-scattering approximation.
Cost: quarter resolution, partial update per frame with temporal accumulation + denoise, early exit on opaque rays. Target ~1-2 ms mid-range, < 1 ms high end.
EEP mapping: the region environment's cloud coverage, density, scale, scroll (wind), colour and texture drive the volumetric layer, so region skies keep working. Altitude and thickness are a viewer setting (EEP has no altitude).
Cloud shadows: a cloud shadow map feeds sun shadows (maps and the RT mask); godrays through gaps; atmosphere distance fade.
Flying through the layer goes through the froxel path (P1), not a hard surface.

Part of #722 (volumetrics epic). Raymarched cloud layer in a shell between two altitudes (Horizon Zero Dawn / Nubis / Frostbite style). - **Shape:** tiling 3D noise (128^3 base + 32^3 detail erosion) + a 2D weather map (coverage, cloud type, wind). - **Lighting:** Beer's law transmittance + powder term, dual Henyey-Greenstein phase (silver lining), multi-scattering approximation. - **Cost:** quarter resolution, partial update per frame with temporal accumulation + denoise, early exit on opaque rays. Target ~1-2 ms mid-range, < 1 ms high end. - **EEP mapping:** the region environment's cloud coverage, density, scale, scroll (wind), colour and texture drive the volumetric layer, so region skies keep working. Altitude and thickness are a viewer setting (EEP has no altitude). - **Cloud shadows:** a cloud shadow map feeds sun shadows (maps and the RT mask); godrays through gaps; atmosphere distance fade. - Flying through the layer goes through the froxel path (P1), not a hard surface.

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2026-10-12 13:15:16 +00:00

sky_line added this to the Slipstream project

2026-10-12 13:15:16 +00:00

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2026-10-12 13:15:16 +00:00

[Epic] Volumetrics: froxel fog, volumetric sky clouds, cloud platforms, volumetric particles #722

sky_line referenced this issue