| name | threejs-volumetric-clouds |
| description | Implement volumetric cloud systems in Three.js. Use for weather-driven density, bounded raymarching, shape/detail erosion, vertical profiles, lighting cones, silver lining, temporal reconstruction, cloud shadows, multiple layers, and scalable quality modes. |
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. This skill owns weather-shaped cloud volumes,
reconstruction, cloud lighting, and cloud shadows.
