Metallic surface issue

[tedbyron]

I'm on 9.5 in the 1 weekend book, for some reason the reflection of the center sphere on the left sphere is different than the reflection on the right sphere - I've made left and right the same color to make it easier to see. Any ideas?

[tedbyron]

rust code:

#[derive(Clone, Copy)]
pub struct Metallic {
    pub albedo: Rgb,
    pub blur: f64,
}

impl Metallic {
    pub fn new(albedo: Rgb, blur: f64) -> Self {
        Self {
            albedo,
            blur: blur.min(1.0),
        }
    }
}

impl Material for Metallic {
    fn scatter(&self, r: &Ray, rec: &HitRecord<'_>, rng: &mut ThreadRng) -> Option<Scatter> {
        let reflected = r.direction.unit().reflect(rec.normal);
        let scattered = Ray::new(
            rec.p,
            reflected + self.blur * Vec3::random_in_unit_sphere(rng),
        );

        if scattered.direction.dot(rec.normal) > 0.0 {
            Some(Scatter::new(scattered, self.albedo))
        } else {
            None
        }
    }
}

reflect method for Vec3

    pub fn reflect(self, normal: Self) -> Self {
        self - 2.0 * self.dot(normal) * normal
    }

[tedbyron]

guess it didn't matter too much in the end :-)