Snow

• Snow cover (SnowCover3D): a snowpack from the weather map, with snowfall, settling, melt, sliding off steep slopes and wind drift.
• Deep snow (SnowSurface3D, snow_deform group): deep snow as geometry with prints and tracks; bodies sink by weight (Bekker) and rest in their own tracks; tracks refill with new snow and wind; print edges stay clean at fine deform resolutions, with pushed-aside snow sliding at its repose angle.
• Falling snow (SnowFall3D): falling and blowing snow from the weather; flake counts, sizes and fall speeds from snowfall measurements, drawn as motion streaks; roofs shelter, snow blows above the wind threshold, get_extinction() feeds fog.
• Snow climate (SnowClimate, recipe; SnowCover3D.climate_map): bakes a winter over the whole terrain from the terrain’s climate recipe and precipitation map, with snow lines, shaded faces that keep their snow and loaded lee slopes; the cover carries it on with the weather and draws it far away.
• Cornices (SnowCornice3D): overhangs on lee crests, with collision; milder ranges grow them too (crest wind speed-up).
• Snowstorms (SnowFall3D.haze_enabled, turbulence): falling and blowing snow haze the air through the weather map (Pomeroy-Male suspension, 118 m visibility at 20 m/s); flakes ride turbulent eddies.
• Shelter (SnowCover3D.canopy_enabled, shelter_collision_mask): ground under roofs and overhangs stays bare; tree crowns hold snow and unload it later.
• Wind moves lying snow (SnowCover3D.wind_transport_enabled): windward shoulders and crests are scoured and the lee fills with wind-packed snow.
• Melt-freeze crusts (SnowCover3D.crust_enabled): a thawed surface refreezes into a crust that hardens each cycle; boots break thin ones into tipped pieces and stand on hard ones.
• Cornices crack and fall (cornice_failure_enabled): a creeping tension crack, tumbling blocks, debris below.
• Icicles (SnowIcicles3D, hazy_core): grown from roof melt water below freezing; clear ice with a hazy core.
• Sparkle: dry snow glints from ice grains (its own mirror lobe, raster and path traced), lost when wet.
• Exact path traced sparkle (snow_exact_glints, off by default): every 2 mm ice grain is a facet hit per ray.
• Snow on materials (BaseMaterial3D snow_enabled): surfaces are covered from the snowpack, flattest facets first, raster and path traced; get_snow_shader_code() for ShaderMaterials.

Images#

Snow cover: deep on the cold summit, thinning to patches lower down.

Thin snow: ground and props partly covered, raster and path traced match.

Snowfall and melt: snow builds up down the slopes, then melts back to the summit.

Snowfall on props: the ground covers first, then the flatter tops of the props.

Deep snow: prints and tracks behind the bodies, raster and path traced.

Tracks: bodies sink in by weight as they move.

Print edges: spikes and toothed walls before; clean rims now.

Falling snow: streaked flakes, none under the roof.

Falling snow in wind.

Snow climate: snow holds on the shaded and lee faces below the snow line.

Cornice: a lip of snow over the lee side of a crest.

Cornice fall: a crack opens behind the lip, then the lip breaks into tumbling blocks.

Icicles: clear ice with a hazy core, longest where the most melt water drips.

Transmission bounces: at the default 3 bounces the icicles stay clear instead of going dark.

Sparkle: dry snow glints in raster and path tracing; wet snow loses it.

Exact sparkle: each ice grain catches the sun on its own, densest round the highlight.

Shelter: bare ground under the roof; tree crowns hold their snow.

Melt-freeze crust: boots break it into tipped plates instead of soft prints.

Wind transport: after a day of 15 m/s wind the windward side is scoured bare and the lee is loaded.