Class fractal_t

Nested Relationships

Nested Types

Inheritance Relationships

Base Type

Class Documentation

class fractal_t : public wt::surface_profile::surface_profile_t

Surface with fractal statistics (aka K-Correlation model). Implements sampling and evaluation.

Surface statistics are parametrized by either of:

  1. Perceptual roughness and \( \gamma \) (log-log space slope of the fractal profile); in the optical regime the perceptual roughness is parameterized such that it produces a lobe shape similar to a classical microfacet surface with a GGX NDF (and matches GGX when \( \gamma=3 \)).

  2. Or, by surface correlation length squared (T), RMS surface roughness ( \( \sigma_h \)) and \( \gamma \).

Public Functions

inline fractal_t(std::string id, f_t gamma, std::unique_ptr<texture::quantity_t<fractalT_t>> &&T_tex, std::unique_ptr<texture::quantity_t<rms_t>> &&sigmah_tex) noexcept
inline fractal_t(std::string id, f_t gamma, std::shared_ptr<texture::texture_t> &&roughness_tex) noexcept
inline virtual variance_t variance(const texture_query_t &query) const noexcept override

Variance of the surface profile.

inline virtual rms_t rms_roughness(const texture_query_t &query) const noexcept override

RMS roughness of the surface profile.

inline virtual f_t alpha(const dir3_t &wi, const dir3_t &wo, const texture_query_t &query) const noexcept override

Fraction of scatter contained in specular term.

Parameters:

k – wavenumber

inline virtual f_t alpha(const dir3_t &wi, const texture_query_t &query) const noexcept override

Fraction of scatter contained in specular term.

Parameters:

k – wavenumber

inline virtual bool is_delta_only(wavenumber_t k) const noexcept override
inline virtual bool needs_interaction_footprint() const noexcept override

Returns true for profiles that make use of the surface interaction footprint data.

inline virtual f_t psd(const dir3_t &wi, const dir3_t &wo, const texture_query_t &query) const noexcept override

Evaluates the fractal lobe power spectral density (PSD).

virtual surface_profile_sample_ret_t sample(const dir3_t &wi, const texture_query_t &query, sampler::sampler_t &sampler) const noexcept override

Samples a scattered direction.

inline virtual f_t pdf(const dir3_t &wi, const dir3_t &wo, const texture_query_t &query) const noexcept override

Provides the sampling density.

virtual scene::element::info_t description() const override

Public Static Functions

static std::unique_ptr<surface_profile_t> load(std::string id, scene::loader::loader_t *loader, const scene::loader::node_t &node, const wt::wt_context_t &context)