Add 3 new type of object: Sphere, Object and Intersect.

Add Intersect object as a way to report where a ray intersect another object and which one it is.
Add an Object base class for all object that can be rendered.
Add the Sphere object.

tests/intersect_test.cpp

@@ -0,0 +1,51 @@
+/*
+ *  DoRayMe - a quick and dirty Raytracer
+ *  Intersect unit tests
+ *
+ *  Created by Manoël Trapier
+ *  Copyright (c) 2020 986-Studio.
+ *
+ */
+#include <intersect.h>
+#include <sphere.h>
+#include <gtest/gtest.h>
+
+
+TEST(IntersectTest, Creating_an_intersect_and_do_some_check)
+{
+    Intersect i;
+
+    ASSERT_EQ(i.count(), 0);
+
+    i.add(newIntersection(1.0, nullptr));
+    i.add(newIntersection(4.2, nullptr));
+
+    ASSERT_EQ(i.count(), 2);
+
+    ASSERT_EQ(i[0]->t, 1.0);
+    ASSERT_EQ(i[1]->t, 4.2);
+}
+
+TEST(IntersectTest, An_intersection_encapsulate_t_and_object)
+{
+    Sphere s = Sphere();
+    Intersection *i = newIntersection(3.5, &s);
+
+    ASSERT_EQ(i->t, 3.5);
+    ASSERT_EQ(i->object, (Object *)&s);
+}
+
+TEST(IntersectTest, Aggregating_intersections)
+{
+    Sphere s = Sphere();
+    Intersection *i1 = newIntersection(1, &s);
+    Intersection *i2 = newIntersection(2, &s);
+
+    Intersect xs = Intersect();
+    xs.add(i1);
+    xs.add(i2);
+
+    ASSERT_EQ(xs.count(), 2);
+    ASSERT_EQ(xs[0]->t, 1);
+    ASSERT_EQ(xs[1]->t, 2);
+}