From 522ab7be397ce5c8dc5373d8257528a9d875bec6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?R=C3=A9mi=20Oudin?= <oudin@crans.org>
Date: Wed, 7 Feb 2018 15:08:16 +0100
Subject: [PATCH] Raw implementation of a Ball

---
 Ball.cpp | 38 ++++++++++++++++++++++++++++++++++++++
 Ball.hpp | 30 ++++++++++++++++++++++++++++++
 2 files changed, 68 insertions(+)
 create mode 100644 Ball.cpp
 create mode 100644 Ball.hpp

diff --git a/Ball.cpp b/Ball.cpp
new file mode 100644
index 0000000..8e01d60
--- /dev/null
+++ b/Ball.cpp
@@ -0,0 +1,38 @@
+#include "Ball.hpp"
+#include <cmath>
+
+Ball::Ball(Point& _center, double _p, double _q) : Center(_center),
+    init_h(_center.z), bounce_number(0), crt_time(0), T(0), A(_center.z), B(0),
+    U(sqrt(2 * G_CTE * _center.z)), surface(_center, _p, _q) {}
+
+void Ball::_compute_pos() {
+    Center.x = A + B * crt_time - (G_CTE / 2) * crt_time * crt_time;
+    surface.update_center_pos(Center);
+}
+
+void Ball::_compute_T_n() {
+    double swap = T;
+    T = swap + 2/G_CTE * pow(1/2, bounce_number - 2) * sqrt(2 * init_h / G_CTE);
+}
+void Ball::_compute_B_n() {
+    B = G_CTE * T + U;
+}
+
+void Ball::_compute_A_n() {
+    A = - G_CTE * T * T / 2 - (U * T);
+}
+
+void Ball::_compute_U_n() {
+    U *= 1/2;
+}
+
+void Ball::update_pos(double dt) {
+    crt_time += dt;
+    if (crt_time >= T) {
+        _compute_T_n();
+        _compute_U_n();
+        _compute_A_n();
+        _compute_B_n();
+    }
+    _compute_pos();
+}
diff --git a/Ball.hpp b/Ball.hpp
new file mode 100644
index 0000000..5980f5d
--- /dev/null
+++ b/Ball.hpp
@@ -0,0 +1,30 @@
+/**
+ * Header file defining a ball.
+ * A ball is the kind of real object, with a physical model, and the implicit
+ * surface.
+ * The physical model is strongly inspired from
+ * http://www.physics-online.info/book1/chapt1/sect1a/problem1a-12/Problem1A-12.htm
+ **/
+
+#include <cstddef>
+#include "spheroid.hpp"
+
+#define G_CTE 9.81
+
+class Ball {
+    private:
+        Point Center;
+        Spheroid surface;
+        double init_h;
+        size_t bounce_number;
+        double crt_time;
+        double A, B, U, T; // Coefficients for the physical model.
+        void _compute_pos();
+        void _compute_A_n();
+        void _compute_B_n();
+        void _compute_U_n();
+        void _compute_T_n();
+    public:
+        Ball(Point& _center, double p, double q);
+        void update_pos(double dt);
+};