Prakash

Prakash (Sanskrit: light, illumination) -- optics and light simulation for AGNOS

Physics of light: ray optics, wave optics, spectral math, lens geometry, atmospheric scattering, and physically-based rendering primitives. Built on hisab for math foundations.

Quick Start

use prakash::ray::{Medium, snell, fresnel_normal, brewster_angle, beer_lambert};
use prakash::spectral::{wavelength_to_rgb, color_temperature_to_rgb, wien_peak};
use prakash::lens::{thin_lens_image_distance, magnification};
use prakash::wave::{malus_law, single_slit_intensity};

// Snell's law: light entering glass from air at 30 degrees
let refracted = snell(Medium::AIR.n, Medium::GLASS.n, 0.5236).unwrap();

// How much light reflects off glass at normal incidence?
let reflectance = fresnel_normal(1.0, 1.52); // ~4%

// What color is 550nm light?
let green = wavelength_to_rgb(550.0).unwrap();

// What color is a 2700K warm bulb?
let warm = color_temperature_to_rgb(2700.0);

// Where does a 50mm lens focus an object at 2 meters?
let image_dist = thin_lens_image_distance(50.0, 2000.0).unwrap();
let mag = magnification(2000.0, image_dist);

// Malus's law: light through a polarizer at 45 degrees
let transmitted = malus_law(1.0, std::f64::consts::FRAC_PI_4); // 50%

Modules

Module	Description
`ray`	Geometric optics: Snell's law, Fresnel equations (s/p/normal/unpolarized), reflection (2D/3D), critical angle, Brewster angle, Beer-Lambert, total internal reflection. 12 built-in materials with refractive indices. Sequential ray tracer, optical system builder, paraxial analysis, cardinal point finder.
`wave`	Wave optics: interference intensity, single/double slit diffraction, diffraction grating, thin film reflectance, Malus's law, polarization (Jones vectors/calculus). 2D Fraunhofer diffraction (FFT), multi-source interference patterns, PSF from wavefront error.
`spectral`	Wavelength to RGB conversion, Planck blackbody radiance, Wien displacement law, color temperature to RGB, photon energy (J and eV), wavelength/frequency conversion. CIE 1931 2-degree observer, XYZ tristimulus, SPD integration, standard illuminants (A/D50/D65/E/F2/F11), color rendering index (CRI). Physical constants (c, h, k_B).
`lens`	Thin lens equation, magnification, lensmaker's equation, combined focal length, depth of field, f-number/NA, mirror focal length, lens classification.
`pbr`	Physically-based rendering: Fresnel-Schlick, GGX/Beckmann NDF, geometry Smith, Cook-Torrance specular BRDF, Lambert diffuse, IOR-to-F0 conversion. Full metallic-roughness pipeline.
`atmosphere`	Atmospheric optics: Rayleigh and Mie scattering, sky color computation, air mass, optical depth.
`error`	Unified error types for all modules.

Feature Flags

Feature	Default	Description
`ray`	yes	Geometric optics, sequential ray tracing, optical system builder
`wave`	yes	Wave optics, interference, diffraction, polarization, FFT patterns
`spectral`	yes	Spectral math, CIE color science, blackbody, color temperature
`lens`	yes	Thin lens, lensmaker, mirrors, depth of field
`pbr`	no	Cook-Torrance BRDF, Fresnel-Schlick, GGX/Beckmann NDF
`atmosphere`	no	Rayleigh/Mie scattering, sky color, air mass
`ai`	no	Daimon/hoosh integration (network deps)
`logging`	no	Structured logging via `PRAKASH_LOG` env var
`full`	--	Enables all features

Examples

Example	Features	Description
`basic_optics`	`ray`, `spectral`, `lens`	Snell's law, Fresnel, wavelength-to-RGB, thin lens
`rainbow`	`ray`, `spectral`	Rainbow simulation via raindrop refraction
`camera_lens`	`ray`, `spectral`, `lens`	Camera lens system analysis with prescriptions
`pbr_materials`	`pbr`	PBR material shading with Cook-Torrance BRDF

Run an example:

cargo run --example basic_optics --features ray,spectral,lens

Architecture

prakash (this crate)
  +-- hisab (math: vectors, geometry, calculus, numerical methods)

Consumer Crates

Crate	Usage
soorat	PBR shading
kiran	Physically-based lighting
ranga	Lens effects

Building

cargo build --all-features
cargo test --all-features

License

GPL-3.0 -- see LICENSE.

prakash 1.0.0