Update spheroid if conflict with a plan at a given height.

spheroid.cpp

@@ -26,3 +26,11 @@ void Spheroid::update_radius() {
 void Spheroid::update_center_pos(Point& _center) {
     center = _center;
 }
+
+void Spheroid::check_plan_collision(double& height) {
+    if ((center.z - p) <= height) {
+        p = center.z-height;
+        update_radius();
+    }
+}
+

spheroid.hpp

@@ -16,6 +16,7 @@ class Spheroid : public ImplicitSurface {
         void update_center_pos(Point& _center);
         void update_radius();
         void set_stiffness(size_t _stiffness);
+        void check_plan_collision(double& height);
         double operator() (double _x, double _y, double _z) {
             return (pow(_x - center.x, 2) / pow(q, 2)
                   + pow(_y - center.y, 2) / pow(q, 2)