[FEAT] Add Normal

raytracing/src/matrix.cpp

@@ -65,7 +65,8 @@ Matrix::Matrix(const Matrix &an_other) : m_rows(an_other.m_rows), m_cols(an_othe
 /* ------------------------------------------------------------------------- */
 
 Matrix::Matrix(const std::initializer_list<std::initializer_list<double>> &a_values) :
-    m_rows(a_values.size()), m_cols(a_values.size())
+    m_rows(a_values.size()),
+    m_cols(a_values.size())
 {
     m_data = std::vector<std::vector<double>>(m_rows, std::vector<double>(m_cols));
     if (!validate_dimensions(a_values))
@@ -187,19 +188,19 @@ Matrix &Matrix::operator=(const Matrix &a_matrix)
 
 /* ------------------------------------------------------------------------- */
 
-bool Matrix::transpose(void)
+Matrix Matrix::transpose(void)
 {
-    std::vector<std::vector<double>> the_copy = m_data;
+    Matrix the_transposed(m_rows, m_cols);
 
     for (int the_row = 0; the_row < m_rows; the_row++)
     {
         for (int the_col = 0; the_col < m_cols; the_col++)
         {
-            m_data[the_col][the_row] = the_copy[the_row][the_col];
+            the_transposed[the_col][the_row] = m_data[the_row][the_col];
         }
     }
 
-    return true;
+    return the_transposed;
 }
 
 /* ------------------------------------------------------------------------- */

raytracing/src/matrix.h

@@ -60,7 +60,7 @@ namespace Raytracer
 
         Matrix &operator=(const Matrix &a_matrix);
 
-        bool transpose(void);
+        Matrix transpose(void);
         double determinant(void) const;
         Matrix sub_matrix(uint8_t a_row, uint8_t a_col) const;
         double minor(uint8_t a_row, uint8_t a_col) const;

raytracing/src/shape.cpp

@@ -96,10 +96,13 @@ void Shape::set_transform(const Matrix &a_transform_matrix)
 
 /* ------------------------------------------------------------------------- */
 
-Tuple Shape::normal_at(const Tuple &a_point)
+Tuple Shape::normal_at(const Tuple &a_world_point)
 {
-    Tuple the_result = a_point - Tuple::Point(0, 0, 0);
-    return the_result.normalize();
+    Tuple the_object_point  = m_transform.inverse() * a_world_point;
+    Tuple the_object_normal = the_object_point - Tuple::Point(0, 0, 0);
+    Tuple the_world_normal  = m_transform.inverse().transpose() * the_object_normal;
+    the_world_normal.set_w(0);
+    return the_world_normal.normalize();
 }
 
 /* ------------------------------------------------------------------------- */

raytracing/src/tuple.cpp

@@ -258,6 +258,34 @@ double Tuple::w(void) const
 
 /* ------------------------------------------------------------------------- */
 
+void Tuple::set_x(double an_x)
+{
+    m_x = an_x;
+}
+
+/* ------------------------------------------------------------------------- */
+
+void Tuple::set_y(double an_y)
+{
+    m_y = an_y;
+}
+
+/* ------------------------------------------------------------------------- */
+
+void Tuple::set_z(double a_z)
+{
+    m_z = a_z;
+}
+
+/* ------------------------------------------------------------------------- */
+
+void Tuple::set_w(double a_w)
+{
+    m_w = a_w;
+}
+
+/* ------------------------------------------------------------------------- */
+
 bool Tuple::is_point(void)
 {
     return double_equal(m_w, kRaytracerTuplePoint);

raytracing/src/tuple.h

@@ -73,6 +73,11 @@ namespace Raytracer
         double z(void) const;
         double w(void) const;
 
+        void set_x(double an_x);
+        void set_y(double an_y);
+        void set_z(double a_z);
+        void set_w(double a_w);
+
         bool is_point(void);
         bool is_vector(void);
 

tests/03_matrix.cpp

@@ -324,9 +324,7 @@ SCENARIO("Transposing a matrix", "[features/matrices.feature]")
                 {0, 8, 3, 8}
             };
 
-            A.transpose();
-
-            REQUIRE(A == transposed);
+            REQUIRE(A.transpose() == transposed);
         }
     }
 }
@@ -337,9 +335,8 @@ SCENARIO("Transposing the identity matrix", "[features/matrices.feature]")
 {
     GIVEN("A <- transpose(identity_matrix)")
     {
-        Matrix A = Matrix::identity();
+        Matrix A = Matrix::identity().transpose();
 
-        A.transpose();
         THEN("A = identity_matrix")
         {
             REQUIRE(A == Matrix::identity());

tests/06_light_shading.cpp

@@ -120,3 +120,51 @@ SCENARIO("The normal is a normalized vector", "[features/spheres.feature]")
         }
     }
 }
+
+/* ------------------------------------------------------------------------- */
+
+SCENARIO("Computing the normal on a translated sphere", "[features/spheres.feature]")
+{
+    GIVEN("s <- sphere()")
+    {
+        Sphere s;
+        AND_GIVEN("set_transform(s, translation(0,1,0))")
+        {
+            s.set_transform(Matrix::translation(0, 1, 0));
+            WHEN("n <- normal_at(s,point(0,1.70711,-0.70711))")
+            {
+                Tuple n = s.normal_at(Tuple::Point(0, 1.70711, -0.70711));
+                THEN("n = vector(0,0.70711, -0.70711)")
+                {
+                    REQUIRE(n == Tuple::Vector(0, 0.70711, -0.70711));
+                }
+            }
+        }
+    }
+}
+
+/* ------------------------------------------------------------------------- */
+
+SCENARIO("Computing the normal on a transformed sphere", "[features/spheres.feature]")
+{
+    GIVEN("s <- sphere()")
+    {
+        Sphere s;
+        AND_GIVEN("m <- scaling(1,0.5,1) * rotation_z(pi/5)")
+        {
+            Matrix m = Matrix::scaling(1, 0.5, 1) * Matrix::rotation_z(std::numbers::pi / 5);
+            AND_GIVEN("set_transform(s, m)")
+            {
+                s.set_transform(m);
+                WHEN("n <- normal_at(s,point(0,sqrt(2)/2,sqrt(2)/2))")
+                {
+                    Tuple n = s.normal_at(Tuple::Point(0, sqrt(2) / 2, -sqrt(2) / 2));
+                    THEN("n = vector(0,97014, -0.24254)")
+                    {
+                        REQUIRE(n == Tuple::Vector(0, 0.97014, -0.24254));
+                    }
+                }
+            }
+        }
+    }
+}