diff --git a/README.md b/README.md
index 26b7594..a681424 100644
--- a/README.md
+++ b/README.md
@@ -20,3 +20,6 @@ Ray Tracing: The Next Week book: http://raytracerchallenge.com/
 # Output
 ### Chapter 05
 ![chapter_05](data/chapter_05.png)
+
+### Chapter 06
+![chapter_06](data/chapter_06.png)
diff --git a/apps/CMakeLists.txt b/apps/CMakeLists.txt
index a98e572..d9394c5 100644
--- a/apps/CMakeLists.txt
+++ b/apps/CMakeLists.txt
@@ -6,5 +6,7 @@ set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
 add_executable(chapter_05 chapter_05.cpp)
-
 target_link_libraries(chapter_05 PRIVATE raytracing gcov)
+
+add_executable(chapter_06 chapter_06.cpp)
+target_link_libraries(chapter_06 PRIVATE raytracing gcov)
diff --git a/apps/chapter_06.cpp b/apps/chapter_06.cpp
new file mode 100644
index 0000000..89017e2
--- /dev/null
+++ b/apps/chapter_06.cpp
@@ -0,0 +1,97 @@
+/*!
+ * chapter_06.cpp
+ *
+ * Copyright (c) 2024, NADAL Jean-Baptiste. All rights reserved.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301 USA
+ *
+ * @Author:  NADAL Jean-Baptiste
+ * @Date: 20/02/2024
+ *
+ */
+
+// This is an independent project of an individual developer. Dear PVS-Studio, please check it.
+// PVS-Studio Static Code Analyzer for C, C++, C#, and Java: http://www.viva64.com
+
+#include <cstdio>
+
+#include <raytracing.h>
+
+/* ------------------------------------------------------------------------- */
+
+#define kImageSize 100
+#define kWallSize  7.0
+#define kWallZ     10
+
+using namespace Raytracer;
+
+/* ------------------------------------------------------------------------- */
+
+int shadow_sphere(uint8_t a_canvas_pixels, double a_wall_size, uint8_t a_wall_z)
+{
+    Canvas the_canvas(a_canvas_pixels, a_canvas_pixels);
+    Sphere the_shape;
+    Tuple the_ray_origin = Tuple::Point(0, 0, -5);
+    PointLight the_light = PointLight(Tuple::Point(-10, 10, -10), Color(1, 1, 1));
+
+    the_shape.material().set_color(Color(1, 0.2, 1));
+
+    double the_pixel_size = a_wall_size / a_canvas_pixels;
+    double the_half       = a_wall_size / 2;
+    double the_world_x, the_world_y;
+
+    // For each row of pixels in the canvas
+    for (int y = 0; y < a_canvas_pixels - 1; y++)
+    {
+        // Compute the world y coordinate (top = +half, bottom = -half)
+        the_world_y = the_half - the_pixel_size * y;
+
+        // For each pixel in the row
+        for (int x = 0; x < a_canvas_pixels; x++)
+        {
+            // Compute the world x coordinate (left = -half, right = half)
+            the_world_x = -the_half + the_pixel_size * x;
+
+            // Describe the point on the wall that the ray will target
+            Tuple the_position = Tuple::Point(the_world_x, the_world_y, a_wall_z);
+            the_position -= the_ray_origin;
+            Ray the_ray(the_ray_origin, the_position.normalize());
+
+            auto the_xs       = the_shape.intersect(the_ray);
+            auto the_intersec = the_xs.hit();
+            if (the_intersec.is_defined())
+            {
+                Tuple the_point  = the_ray.position(the_intersec.distance_t());
+                Tuple the_normal = the_intersec.object().normal_at(the_point);
+                Tuple the_eye    = -the_ray.direction();
+                Color the_color  = the_intersec.object().material().lighting(the_light, the_point, the_eye, the_normal);
+                the_canvas.write_pixel(x, y, the_color);
+            }
+        }
+    }
+
+    the_canvas.save_to_file("chapter06.ppm");
+
+    return 0;
+}
+
+/* ------------------------------------------------------------------------- */
+
+int main(void)
+{
+    printf("Chapter 06 example.\n");
+    return shadow_sphere(kImageSize, kWallSize, kWallZ);
+}
diff --git a/data/chapter_06.png b/data/chapter_06.png
new file mode 100644
index 0000000..f8b342e
Binary files /dev/null and b/data/chapter_06.png differ
diff --git a/raytracing/src/material.cpp b/raytracing/src/material.cpp
index b26b216..928b626 100644
--- a/raytracing/src/material.cpp
+++ b/raytracing/src/material.cpp
@@ -60,6 +60,13 @@ const Color &Material::color(void) const
 
 /* ------------------------------------------------------------------------- */
 
+void Material::set_color(const Color &a_color)
+{
+    m_color = a_color;
+}
+
+/* ------------------------------------------------------------------------- */
+
 const double &Material::ambient(void) const
 {
     return m_ambient;
@@ -116,7 +123,8 @@ void Material::set_shininess(double a_value)
 
 /* ------------------------------------------------------------------------- */
 
-Color Material::lighting(const PointLight &a_light, const Tuple &a_point, const Tuple &an_eyev, const Tuple &a_normalv)
+Color Material::lighting(const PointLight &a_light, const Tuple &a_point, const Tuple &an_eyev,
+                         const Tuple &a_normalv) const
 {
     Color the_effective_color;
     Tuple the_light_v, the_reflect_v;
@@ -137,8 +145,7 @@ Color Material::lighting(const PointLight &a_light, const Tuple &a_point, const
 
     if (the_light_dot_normal < 0)
     {
-        the_diffuse  = Color::Black();
-        the_specular = Color::Black();
+        the_diffuse = the_specular = Color::Black();
     }
     else
     {
diff --git a/raytracing/src/material.h b/raytracing/src/material.h
index ce70c71..a9a0615 100644
--- a/raytracing/src/material.h
+++ b/raytracing/src/material.h
@@ -44,6 +44,7 @@ namespace Raytracer
         bool operator==(const Material &a_material) const;
 
         const Color &color(void) const;
+        void set_color(const Color &a_color);
 
         const double &ambient(void) const;
         void set_ambient(double a_value);
@@ -57,7 +58,8 @@ namespace Raytracer
         const double &shininess(void) const;
         void set_shininess(double a_value);
 
-        Color lighting(const PointLight &a_light, const Tuple &a_point, const Tuple &an_eyev, const Tuple &a_normalv);
+        Color lighting(const PointLight &a_light, const Tuple &a_point, const Tuple &an_eyev,
+                       const Tuple &a_normalv) const;
 
     private:
         Color m_color;
diff --git a/raytracing/src/ray.cpp b/raytracing/src/ray.cpp
index 3f3e8b8..f2e8872 100644
--- a/raytracing/src/ray.cpp
+++ b/raytracing/src/ray.cpp
@@ -55,6 +55,13 @@ const Tuple &Ray::direction(void) const
 
 /* ------------------------------------------------------------------------- */
 
+Tuple &Ray::direction(void)
+{
+    return m_direction;
+}
+
+/* ------------------------------------------------------------------------- */
+
 Tuple Ray::position(double a_distance)
 {
     return m_origin + m_direction * a_distance;
diff --git a/raytracing/src/ray.h b/raytracing/src/ray.h
index 6074b34..d3ee1b6 100644
--- a/raytracing/src/ray.h
+++ b/raytracing/src/ray.h
@@ -43,6 +43,7 @@ namespace Raytracer
 
         const Tuple &origin(void) const;
         const Tuple &direction(void) const;
+        Tuple &direction(void);
 
         Tuple position(double a_distance);
 
diff --git a/raytracing/src/shape.cpp b/raytracing/src/shape.cpp
index 9af2d2e..756bc0e 100644
--- a/raytracing/src/shape.cpp
+++ b/raytracing/src/shape.cpp
@@ -48,13 +48,13 @@ Shape::Shape(void) : m_id(kNothing), m_transform(Matrix::identity())
 
 /* ------------------------------------------------------------------------- */
 
-Shape::Shape(Shape &a_copy) : m_id(a_copy.m_id), m_transform(Matrix::identity())
+Shape::Shape(Shape &a_copy) : m_id(a_copy.m_id), m_transform(Matrix::identity()), m_material(a_copy.m_material)
 {
 }
 
 /* ------------------------------------------------------------------------- */
 
-Shape::Shape(const Shape &a_copy) : m_id(a_copy.m_id), m_transform(Matrix::identity())
+Shape::Shape(const Shape &a_copy) : m_id(a_copy.m_id), m_transform(Matrix::identity()), m_material(a_copy.m_material)
 {
 }
 
@@ -69,6 +69,7 @@ const Shape &Shape::operator=(const Shape &a_shape)
 
     m_id        = a_shape.m_id;
     m_transform = a_shape.m_transform;
+    m_material  = a_shape.m_material;
 
     return *this;
 }
@@ -77,7 +78,7 @@ const Shape &Shape::operator=(const Shape &a_shape)
 
 bool Shape::operator==(const Shape &a_shape) const
 {
-    return (m_id == a_shape.m_id) && (m_transform == a_shape.m_transform);
+    return (m_id == a_shape.m_id) && (m_transform == a_shape.m_transform) && (m_material == a_shape.m_material);
 }
 
 /* ------------------------------------------------------------------------- */
@@ -96,6 +97,13 @@ void Shape::set_transform(const Matrix &a_transform_matrix)
 
 /* ------------------------------------------------------------------------- */
 
+Material &Shape::material(void)
+{
+    return m_material;
+}
+
+/* ------------------------------------------------------------------------- */
+
 const Material &Shape::material(void) const
 {
     return m_material;
@@ -110,7 +118,7 @@ void Shape::set_material(const Material &a_material)
 
 /* ------------------------------------------------------------------------- */
 
-Tuple Shape::normal_at(const Tuple &a_world_point)
+Tuple Shape::normal_at(const Tuple &a_world_point) const
 {
     Tuple the_object_point  = m_transform.inverse() * a_world_point;
     Tuple the_object_normal = the_object_point - Tuple::Point(0, 0, 0);
diff --git a/raytracing/src/shape.h b/raytracing/src/shape.h
index 8bd21fe..c8da14d 100644
--- a/raytracing/src/shape.h
+++ b/raytracing/src/shape.h
@@ -55,10 +55,11 @@ namespace Raytracer
         Matrix &transform(void);
         void set_transform(const Matrix &a_transform_matrix);
 
+        Material &material(void);
         const Material &material(void) const;
         void set_material(const Material &a_material);
 
-        Tuple normal_at(const Tuple &a_point);
+        Tuple normal_at(const Tuple &a_point) const;
 
         virtual Intersections intersect(Ray &a_ray);