src/material.rs


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use cgmath::Vector3;
use rand::prelude::*;
use crate::ray::{Ray, NextRay};
use crate::hittable::Hit;
use crate::random::random_unit_vector;

pub trait Material {
    fn scatter(&self, rng: &mut ThreadRng, ray: &Ray, hit: &Hit) -> Option<NextRay>;
}

pub struct Lambertian {
    pub albedo: Vector3<f64>
}

impl Lambertian {
    pub fn new(albedo: Vector3<f64>) -> Lambertian {
        Lambertian { albedo }
    }
}

impl Material for Lambertian {
    fn scatter(&self, rng: &mut ThreadRng, _ray: &Ray, hit: &Hit) -> Option<NextRay> {
        let scatter_direction = hit.normal + random_unit_vector(rng);
        Some(NextRay::new(self.albedo, Ray::new(hit.p, scatter_direction)))
    }
}