From 2e24fef5acada5d63dfa6517d628356ddb8c72f2 Mon Sep 17 00:00:00 2001
From: Phireh <Phireh@fukurokuju.dev>
Date: Sat, 21 Aug 2021 22:39:59 +0200
Subject: [PATCH] New scatter formula

---
 main.cpp |  2 +-
 vec3.hpp | 16 ++++++++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/main.cpp b/main.cpp
index 8f30161..1c16754 100644
--- a/main.cpp
+++ b/main.cpp
@@ -21,7 +21,7 @@ color ray_color(const ray& r, const hittable& world, int32_t depth)
     hit_record rec;
     if (world.hit(r, 0.001, INFINITY, rec))
     {
-        point3 target = rec.p + rec.normal + random_in_unit_sphere();
+        point3 target = rec.p + rec.normal + random_in_hemisphere(rec.normal);
         return 0.5 * ray_color(ray(rec.p, target - rec.p), world, depth-1);
     }
     vec3 unit_direction = normalize(r.direction);
diff --git a/vec3.hpp b/vec3.hpp
index acc9513..614938a 100644
--- a/vec3.hpp
+++ b/vec3.hpp
@@ -159,4 +159,20 @@ vec3 random_in_unit_sphere()
     }
 }
 
+// Returns a normalized version of the above vector
+vec3 random_unit_vector()
+{
+    return normalize(random_in_unit_sphere());
+}
+
+vec3 random_in_hemisphere(const vec3& normal)
+{
+    vec3 in_unit_sphere = random_in_unit_sphere();
+    
+    if (dot(in_unit_sphere, normal) > 0.0)
+        return in_unit_sphere;
+    else
+        return -in_unit_sphere;
+}
+
 #endif