Threejs Volumetric Clouds

Volumetric Clouds

Cloud quality comes from density organization, lighting, and temporal stability—not from increasing march steps over unstructured noise.

System order

• Define the cloud volume and layer bounds.
• Generate or source weather, base-shape, detail, and turbulence fields.
• Build a density function with vertical and weather profiles.
• Raymarch only the bounded occupied segment.
• Integrate transmittance and lighting front-to-back.
• Reconstruct low-resolution output temporally.
• Project a separate low-cost cloud-shadow solution.

Read references/weather-volume-and-reconstruction.md before implementing or auditing the cloud system.

Read the weather volume cloud entry

and its source/ modules for weather-layer ownership, spherical shell bounds,

authored shape/detail sampling, cloud shadow maps, temporal upscale,

atmospheric composition, and package-owned diagnostics.

Required controls

• coverage, cloud type, precipitation, and anvil bias;
• base/top altitude and vertical density profile;
• shape/detail scales and erosion;
• wind for each field;
• primary step count, light step count, and empty-space policy;
• history weight and disocclusion threshold;
• cloud-shadow extent, resolution, and update rate.

Failure conditions

• density is only fbm(position);
• the raymarch traverses the full camera range;
• detail noise adds density instead of eroding shaped masses;
• temporal history is accepted across disocclusion;
• shadows use the full beauty raymarch;
• every cloud layer shares the same wind and density profile.

Routing boundary

Use $threejs-atmosphere-aerial-perspective for molecular/aerosol scattering

without weather density. Use $threejs-procedural-vfx for emissive aurora

curtain slabs or bounded interactive voxel fire and smoke with velocity,

pressure, emitter, and collision fields. This skill owns weather-shaped cloud

volumes, reconstruction, cloud lighting, and cloud shadows.