From b28a6cc7f5d1e8dc21b006d3fdd22d61bf9ef153 Mon Sep 17 00:00:00 2001
From: dengqn <someonedeng@qq.com>
Date: Tue, 12 Aug 2025 17:37:25 +0800
Subject: [PATCH] 10.6.Fuzzy Reflection

---
 src/main.rs     |  4 ++--
 src/material.rs | 11 ++++-------
 src/vec3.rs     |  2 +-
 3 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index 7b23ee7..4f3a6ac 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -51,9 +51,9 @@ fn camera_render() {
     let plane_m = Some(MaterialKind::Lambertian(Lambertian{albedo: Color::new(0.899, 0.899, 0.999)}));
     // let plane2_m = Some(MaterialKind::Metal(Metal{albedo: Color::new(0.784,0.784,0.784)}));
     let center_m = Some(MaterialKind::Lambertian(Lambertian{albedo: Color::new(0.5, 0.5, 0.5)}));
-    let left_m = Some(MaterialKind::Metal(Metal{albedo: Color::new(0.799, 0.599, 0.799)}));
+    let left_m = Some(MaterialKind::Metal(Metal{albedo: Color::new(0.799, 0.599, 0.799), fuzz: 0.0005}));
     let left_behind_m = Some(MaterialKind::Lambertian(Lambertian{albedo: Color::new(0.799, 0.599, 0.599)}));
-    let right_m = Some(MaterialKind::Metal(Metal{albedo: Color::new(0.8, 0.6, 0.2)}));
+    let right_m = Some(MaterialKind::Metal(Metal{albedo: Color::new(0.8, 0.6, 0.2), fuzz: 0.3}));
 
     world.put(Box::new(Sphere::new(Point::new(0.0,    0.0, -1.0), 0.5, center_m)));
     world.put(Box::new(Sphere::new(Point::new(-1.0,    0.0, -1.0), 0.5, left_m)));
diff --git a/src/material.rs b/src/material.rs
index fe1fd62..26b8ff8 100644
--- a/src/material.rs
+++ b/src/material.rs
@@ -46,26 +46,23 @@ impl Material for Lambertian {
 #[derive(Debug)]
 pub struct Metal {
     pub albedo: Color,
+    pub fuzz: f32
 }
 
 impl Clone for Metal {
     fn clone(&self) -> Self {
         Metal {
             albedo: self.albedo,
+            fuzz: self.fuzz
         }
     }
 }
 
 impl Material for Metal {
     fn scatter(&self, r_in: &Ray, hit_record: &mut HitRecord, attenuation: &mut Color, scattered: &mut Ray) -> bool {
-        /*
-            vec3 reflected = reflect(r_in.direction(), rec.normal);
-            scattered = ray(rec.p, reflected);
-            attenuation = albedo;
-            return true;
-        */
         let reflected = reflect(r_in.direction, hit_record.normal);
-        *scattered = Ray::new(hit_record.p, reflected);
+        let fuzz_relected = (reflected / reflected.length_squared()) + (Vec3::random_unit() * self.fuzz);
+        *scattered = Ray::new(hit_record.p, fuzz_relected);
         *attenuation = self.albedo.clone();
         true
     }
diff --git a/src/vec3.rs b/src/vec3.rs
index 24ce443..ebe21ac 100644
--- a/src/vec3.rs
+++ b/src/vec3.rs
@@ -50,7 +50,7 @@ impl Vec3 {
     pub fn random_unit() -> Self {
         loop {
             let v = Vec3::random();
-            if f32::MIN < v.length_squared() && v.length_squared() <= 1.0 {
+            if 1e-160 < v.length_squared() && v.length_squared() <= 1.0 {
                 return v / v.length_squared();
             }
         }