Rough implementation of an ellipsoid.

In an extremely simple model, the ball will deform as an ellipsoid
during the bounce process.

ellipsoid.cpp

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+/**
+ * Implementation of an ellipsoid
+ **/
+
+#include "ellipsoid.hpp"
+
+Ellipsoid::Ellipsoid(Point& _center, size_t _p, size_t _q) :
+    center(_center), p(_p), q(_q), stiffness(0) {
+        _compute_volume();
+    }
+
+void Ellipsoid::_compute_volume() {
+    V = (4/3) * PI * p * q * q;
+}
+
+void Ellipsoid::set_stiffness(size_t _stiffness) {
+    stiffness = _stiffness;
+}

ellipsoid.hpp

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+/**
+ * Defines an ellispoid, which is a basic interpretaion of the ball when it is
+ * bouncing.
+ **/
+
+#include <cstddef>
+#include "Implicit.hpp"
+#include "common_structures.hpp"
+
+const double PI = 3.141592653589793;
+
+class Ellipsoid : public ImplicitSurface {
+    public:
+        Ellipsoid(Point& _center, size_t _p, size_t _q);
+        void update_center_pos(size_t dt);
+        void set_stiffness(size_t _stiffness);
+    private:
+        /**
+         * p corresponds to the half-height of the ball,
+         * q to the radius of the ball,
+         * V is the volume. Extremely useful to have a constant volume in the
+         * ball
+        **/
+        size_t stiffness;
+        size_t p, q;
+        double V;
+        Point& center;
+        void _compute_volume();
+        void _compute_pos(size_t t);
+};