Struct tray_rust::bxdf::bsdf::BSDF

pub struct BSDF<'a> {
    pub p: Point,
    pub n: Normal,
    pub ng: Normal,
    pub tan: Vector,
    pub bitan: Vector,
    pub eta: f32,
    // some fields omitted
}

The BSDF contains the various BRDFs and BTDFs that describe the surface's properties at some point. It also transforms incident and outgoing light directions into shading space to make the BxDFs easier to implement. TODO: We really need the memory pool. Each time we get the bsdf from a material we need to allocate a decent amount of stuff since they each need their own tangent, bitangent and differential geometry reference.

Fields

p: Point

The hit point

n: Normal

Shading normal, may be perturbed by bump mapping

ng: Normal

The actual geometry normal

tan: Vector

Tangent vector for the surface

bitan: Vector

Bitangent vector for the surface

eta: f32

Refractive index of the geometry

Methods

impl<'a> BSDF<'a>

pub fn new<'b>(
    bxdfs: &'a [&'a dyn BxDF],
    eta: f32,
    dg: &DifferentialGeometry<'b>
) -> BSDF<'a>

Create a new BSDF using the BxDFs passed to shade the differential geometry with refractive index eta

pub fn num_bxdfs(&self) -> usize

Return the total number of BxDFs

pub fn num_matching(&self, flags: EnumSet<BxDFType>) -> usize

Return the number of BxDFs matching the flags

pub fn to_shading(&self, v: &Vector) -> Vector

Transform the vector from world space to shading space

pub fn from_shading(&self, v: &Vector) -> Vector

Transform the vectro from shading space to world space

pub fn eval(
    &self,
    wo_world: &Vector,
    wi_world: &Vector,
    flags: EnumSet<BxDFType>
) -> Colorf

Evaluate the BSDF for the outgoing and incident light directions w_o and w_i in world space, sampling the desired subset of BxDFs selected by the flags passed. wo_world and wi_world should point from the hit point in the outgoing and incident light directions respectively.

pub fn sample(
    &self,
    wo_world: &Vector,
    flags: EnumSet<BxDFType>,
    samples: &Sample
) -> (Colorf, Vector, f32, EnumSet<BxDFType>)

Sample a component of the BSDF to get an incident light direction for light leaving the surface along w_o. samples are the 3 random values to use when sampling a component of the BSDF and a the chosen BSDF Returns the color, direction, pdf and the type of BxDF that was sampled.

pub fn pdf(
    &self,
    wo_world: &Vector,
    wi_world: &Vector,
    flags: EnumSet<BxDFType>
) -> f32

Compute the pdf for sampling the pair of incident and outgoing light directions for the BxDFs matching the flags set