From dae55f5eabbf586833c88d6b145c55a6faa95636 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?R=C3=A9mi=20Oudin?= <oudin@crans.org>
Date: Wed, 31 Jan 2018 16:43:53 +0100
Subject: [PATCH] Rough implementation of an ellipsoid.

In an extremely simple model, the ball will deform as an ellipsoid
during the bounce process.
---
 ellipsoid.cpp | 18 ++++++++++++++++++
 ellipsoid.hpp | 30 ++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)
 create mode 100644 ellipsoid.cpp
 create mode 100644 ellipsoid.hpp

diff --git a/ellipsoid.cpp b/ellipsoid.cpp
new file mode 100644
index 0000000..7b43416
--- /dev/null
+++ b/ellipsoid.cpp
@@ -0,0 +1,18 @@
+/**
+ * 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;
+}
diff --git a/ellipsoid.hpp b/ellipsoid.hpp
new file mode 100644
index 0000000..f4eea39
--- /dev/null
+++ b/ellipsoid.hpp
@@ -0,0 +1,30 @@
+/**
+ * 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);
+};