[FEAT] Add Plane Chapter 09 is done

tests/09_planes.cpp

@@ -244,3 +244,142 @@ SCENARIO("Computing the normal on a transformed shape", "[features/shapes.featur
         }
     }
 }
+
+/* ------------------------------------------------------------------------- */
+
+SCENARIO("The normal of a plane is constant everywhere", "[features/planes.feature]")
+{
+    GIVEN("p <- plane()")
+    {
+        Plane p;
+        WHEN("n1 <- local_normal_at(p, point(0, 0, 0)))")
+        {
+            Tuple n1 = p.local_normal_at(Tuple::Point(0, 0, 0));
+            AND_WHEN("n2 <- local_normal_at(p, point(10, 0, 0)))")
+            {
+                Tuple n2 = p.local_normal_at(Tuple::Point(10, 0, 0));
+                AND_WHEN("n3 <- local_normal_at(p, point(-5, 0, 150)))")
+                {
+                    Tuple n3 = p.local_normal_at(Tuple::Point(-5, 0, 150));
+
+                    THEN("n1 = vector(0, 1, 0)")
+                    {
+                        REQUIRE(n1 == Tuple::Vector(0, 1, 0));
+                    }
+                    AND_THEN("n2 = vector(0, 1, 0)")
+                    {
+                        REQUIRE(n1 == Tuple::Vector(0, 1, 0));
+                    }
+                    AND_THEN("n3 = vector(0, 1, 0)")
+                    {
+                        REQUIRE(n1 == Tuple::Vector(0, 1, 0));
+                    }
+                }
+            }
+        }
+    }
+}
+
+/* ------------------------------------------------------------------------- */
+
+SCENARIO("Intersect with a ray parallel to the plane", "[features/planes.feature]")
+{
+    GIVEN("p <- plane()")
+    {
+        Plane p;
+        AND_GIVEN("r <- ray(point(0, 10, 0), vector(0, 0, 1))")
+        {
+            Ray r(Tuple::Point(0, 10, 0), Tuple::Vector(0, 0, 1));
+            WHEN("xs <-local_intersect(p, r)")
+            {
+                Intersections xs = p.local_intersect(r);
+                THEN("xs is empty")
+                {
+                    REQUIRE(xs.count() == 0);
+                }
+            }
+        }
+    }
+}
+
+/* ------------------------------------------------------------------------- */
+
+SCENARIO("Intersect with a coplanar ray", "[features/planes.feature]")
+{
+    GIVEN("p <- plane()")
+    {
+        Plane p;
+        AND_GIVEN("r <- ray(point(0, 0, 0), vector(0, 0, 1))")
+        {
+            Ray r(Tuple::Point(0, 0, 0), Tuple::Vector(0, 0, 1));
+            WHEN("xs <-local_intersect(p, r)")
+            {
+                Intersections xs = p.local_intersect(r);
+                THEN("xs is empty")
+                {
+                    REQUIRE(xs.count() == 0);
+                }
+            }
+        }
+    }
+}
+
+/* ------------------------------------------------------------------------- */
+
+SCENARIO("A ray Intersecting a plane from above", "[features/planes.feature]")
+{
+    GIVEN("p <- plane()")
+    {
+        Plane p;
+        AND_GIVEN("r <- ray(point(0, 1, 0), vector(0, -1, 0))")
+        {
+            Ray r(Tuple::Point(0, 1, 0), Tuple::Vector(0, -1, 0));
+            WHEN("xs <-local_intersect(p, r)")
+            {
+                Intersections xs = p.local_intersect(r);
+                THEN("xs.count = 1")
+                {
+                    REQUIRE(xs.count() == 1);
+                }
+                AND_THEN("xs[0].t = 1")
+                {
+                    REQUIRE(xs[0].distance_t() == 1);
+                }
+                AND_THEN("xs[0].object = p")
+                {
+                    REQUIRE(xs[0].object() == p);
+                }
+            }
+        }
+    }
+}
+
+/* ------------------------------------------------------------------------- */
+
+SCENARIO("A ray Intersecting a plane from below", "[features/planes.feature]")
+{
+    GIVEN("p <- plane()")
+    {
+        Plane p;
+        AND_GIVEN("r <- ray(point(0, -1, 0), vector(0, 1, 0))")
+        {
+            Ray r(Tuple::Point(0, -1, 0), Tuple::Vector(0, 1, 0));
+            WHEN("xs <-local_intersect(p, r)")
+            {
+                Intersections xs = p.local_intersect(r);
+                THEN("xs.count = 1")
+                {
+                    REQUIRE(xs.count() == 1);
+                }
+                AND_THEN("xs[0].t = 1")
+                {
+                    REQUIRE(xs[0].distance_t() == 1);
+                }
+                AND_THEN("xs[0].object = p")
+                {
+                    REQUIRE(xs[0].object() == p);
+                }
+            }
+        }
+    }
+}