Module atmosphere 

Atmospheric and environmental rendering mathematics.

Covers Rayleigh/Mie scattering, physical sky models, volumetric fog, procedural clouds, Gerstner ocean waves, and shadow-mapping helpers.

All math is CPU-side, using glam::{Vec2, Vec3, Vec4, Mat4}.

Structs

AtmosphereParams

Full atmosphere parameter set for physical sky rendering.

CloudLayer

A single cloud layer definition.

MieScattering

Mie scattering parameters for Earth’s atmosphere.

OceanWave

A single Gerstner wave component.

Preetham

Simplified Preetham sky model.

RayleighScattering

Rayleigh scattering parameters for Earth’s atmosphere.

SkyModel

Physical sky colour model using single-scattering path integrals.

TransmittanceLut

Precomputed transmittance lookup table.

VolumetricFog

Homogeneous volumetric fog parameters.

Functions

bias_matrix

Bias matrix to map NDC [-1,1] to UV [0,1] and depth [0,1].

cascade_shadow_splits

Compute cascade split distances for Cascaded Shadow Maps (CSM).

cornette_shanks_phase

Cornette-Shanks phase function — more accurate than HG for large g.

exponential_height_fog

Exponential height-fog density at world position pos.

fog_inscattering

In-scattering colour accumulated along a ray through volumetric fog toward a single directional light.

fog_transmittance

Beer-Lambert transmittance through homogeneous fog of distance.

gerstner_wave

Compute Gerstner wave displacement at horizontal position pos and time time.

light_space_matrix

Compute a light-space view matrix and ortho projection for a directional light, tightly fitted to a scene AABB.

mie_phase

Henyey-Greenstein phase function for Mie scattering.

ocean_normal

Compute the analytic surface normal of a Gerstner wave field.

optical_depth

Compute the optical depth (column density) from start to the atmosphere boundary, and also toward the sun for shadow computation.

pcf_kernel

Generate a Poisson-disc PCF kernel of size taps.

pcss_blocker_search_uv

Compute the PCSS blocker-search UV radius.

rayleigh_phase

Rayleigh phase function.

raymarch_cloud

Raymarche through cloud layers and return Vec4(rgb_color, alpha).

sample_cloud_density

Evaluate procedural cloud density at pos using layered FBM noise.

water_color

Simple deep-water colour model.

water_fresnel

Fresnel reflectance for water (IOR = 1.333) using Schlick approximation.