64 lines
2.0 KiB
Rust
64 lines
2.0 KiB
Rust
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use crate::ray::Ray;
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use crate::hittable::HitRecord;
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use crate::Vec3;
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use rand::Rng;
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use rand::rngs::SmallRng;
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use rand::distributions::Uniform;
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#[derive(Copy, Clone, Debug)]
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pub enum Material{
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Lambertian{ albedo: Vec3 },
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Metal{ albedo:Vec3, fuzz: f32 },
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}
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impl Material {
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pub fn scatter(
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&self,
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ray_in: Ray,
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rec: HitRecord,
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attenuation: &mut Vec3,
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scattered: &mut Ray,
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srng: &mut SmallRng,
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distrib: Uniform<f32>,
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) -> bool {
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match self {
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Material::Lambertian { albedo } => {
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let scatter_dir = rec.normal + Vec3::rand_unit_vector(srng, distrib);
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// The compiler might be smart enough to compute this ^^^ just once. In which case,
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// I don't need to do this weird dance. Oh well. It'll work.
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let scatter_dir = if scatter_dir.near_zero() { // if near zero,
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rec.normal // replace with normal
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} else {
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scatter_dir // else preserve current
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};
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//TODO: Revisit this out-parameter pattern
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// It's a side effect of C++'s obtuse move semantics (and the RTIOW author not
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// using them at all)
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*scattered = Ray{
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orig: rec.p,
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dir: scatter_dir
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};
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*attenuation = *albedo; // deref on both sides? Wacky
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return true;
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},
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Material::Metal { albedo, fuzz } => {
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let reflected = Vec3::reflect(
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Vec3::as_unit(&ray_in.dir),
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rec.normal
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);
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*scattered = Ray{
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orig: rec.p,
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dir: reflected + Vec3::rand_in_unit_sphere(srng, distrib) * *fuzz,
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};
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*attenuation = *albedo;
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return Vec3::dot(scattered.dir, rec.normal) > 0.0;
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},
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}
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}
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}
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