Add transformation to objects.

tests/sphere_test.cpp

@@ -8,6 +8,7 @@
  */
 #include <ray.h>
 #include <sphere.h>
+#include <transformation.h>
 #include <gtest/gtest.h>
 
 
@@ -62,4 +63,46 @@ TEST(SphereTest, A_sphere_is_behind_a_ray)
     ASSERT_EQ(xs.count(), 2);
     ASSERT_EQ(xs[0].t, -6.0);
     ASSERT_EQ(xs[1].t, -4.0);
+}
+
+TEST(SphereTest, A_sphere_default_transformation)
+{
+    Sphere s = Sphere();
+    ASSERT_EQ(s.transformMatrix, Matrix4().identity());
+}
+
+TEST(SphereTest, Changing_a_sphere_transformation)
+{
+    Sphere s = Sphere();
+    Matrix t = translation(2, 3, 4);
+
+    s.setTransform(t);
+
+    ASSERT_EQ(s.transformMatrix, t);
+}
+
+TEST(SphereTest, Intersecting_a_scaled_sphere_with_a_ray)
+{
+    Ray r = Ray(Point(0, 0, -5), Vector(0, 0, 1));
+    Sphere s = Sphere();
+
+    s.setTransform(scaling(2, 2, 2));
+
+    Intersect xs = s.intersect(r);
+
+    ASSERT_EQ(xs.count(), 2);
+    ASSERT_EQ(xs[0].t, 3.0);
+    ASSERT_EQ(xs[1].t, 7.0);
+}
+
+TEST(SphereTest, Intersecting_a_translated_sphere_with_a_ray)
+{
+    Ray r = Ray(Point(0, 0, -5), Vector(0, 0, 1));
+    Sphere s = Sphere();
+
+    s.setTransform(translation(5, 0, 0));
+
+    Intersect xs = s.intersect(r);
+
+    ASSERT_EQ(xs.count(), 0);
 }