Smooth triangles! And support for them in the OBJ File parser.

Also add an interesting tea party scene!

source/shapes/smoothtriangle.cpp

@@ -0,0 +1,28 @@
+/*
+ *  DoRayMe - a quick and dirty Raytracer
+ *  Smooth Triangle implementation
+ *
+ *  Created by Manoël Trapier
+ *  Copyright (c) 2020 986-Studio.
+ *
+ */
+#include <ray.h>
+#include <shape.h>
+#include <triangle.h>
+#include <smoothtriangle.h>
+#include <math_helper.h>
+#include <renderstat.h>
+
+SmoothTriangle::SmoothTriangle(Point p1, Point p2, Point p3, Vector n1, Vector n2, Vector n3) : Triangle(p1, p2, p3),
+                                                                                                n1(n1), n2(n2), n3(n3)
+{
+    this->type = SHAPE_SMOOTHTRIANGLE;
+    stats.addSmoothTriangle();
+}
+
+Tuple SmoothTriangle::localNormalAt(Tuple point, Intersection *hit)
+{
+    return (this->n2 * hit->u +
+            this->n3 * hit->v +
+            this->n1 * (1 - hit->u - hit->v)).normalise();
+}