48 lines
1.7 KiB
Rust
48 lines
1.7 KiB
Rust
use nalgebra::{convert, RealField, Vector3};
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use super::algebra_utils::try_change_of_basis_matrix;
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use super::colour::ColourRgbF;
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use super::raycasting::{IntersectionInfo, Ray};
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use super::sampler::Sampler;
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pub trait Integrator<T: RealField> {
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fn integrate(&self, sampler: &Sampler<T>, info: &IntersectionInfo<T>) -> ColourRgbF<T>;
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}
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pub struct DirectionalLight<T: RealField> {
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pub direction: Vector3<T>,
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pub colour: ColourRgbF<T>,
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}
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pub struct WhittedIntegrator<T: RealField> {
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pub ambient_light: ColourRgbF<T>,
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pub lights: Vec<DirectionalLight<T>>,
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}
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// TODO: Get rid of the magic bias number, which should be calculated base on expected error
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// bounds and tangent direction
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impl<T: RealField> Integrator<T> for WhittedIntegrator<T> {
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fn integrate(&self, sampler: &Sampler<T>, info: &IntersectionInfo<T>) -> ColourRgbF<T> {
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self.lights
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.iter()
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.map(|light| {
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let basis_change =
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try_change_of_basis_matrix(&info.tangent, &info.cotangent, &info.normal)
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.expect("Normal, tangent and cotangent don't for a valid basis.");
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match sampler
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.sample(&Ray::new(info.location, light.direction).bias(convert(0.000000001)))
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{
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Some(_) => self.ambient_light,
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None => {
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info.material.bsdf()(
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basis_change * info.retro,
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basis_change * light.direction,
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light.colour,
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) * light.direction.dot(&info.normal).abs()
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}
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}
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})
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.fold(self.ambient_light, |a, b| a + b)
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}
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}
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