diff --git a/spheroid.cpp b/spheroid.cpp
index 2c0a60b..af24061 100644
--- a/spheroid.cpp
+++ b/spheroid.cpp
@@ -5,7 +5,7 @@
 #include "spheroid.hpp"
 
 Spheroid::Spheroid(Point& _center, size_t _p, size_t _q) :
-    ImplicitSurface(_center), init_p(_p), p(_p), q(_q), stiffness(0) {
+    ImplicitSurface(_center), normal_vector(Point(0,0,1)), init_p(_p), p(_p), q(_q), stiffness(0) {
         _compute_volume();
     }
 
@@ -52,6 +52,15 @@ void Spheroid::check_vertical_plan_collision(double& abscissa) {
     }
 }
 
+void Spheroid::check_perlin_collision(PerlinNoise perlin) {
+    double height = perlin.noise(center.x, center.y);
+    if ((center.z - p) <= height) {
+        p = fmin(init_p, center.z- height );
+        normal_vector = perlin.normal_vector(center.x, center.y);
+        update_radius();
+    }
+}
+
 
 double Spheroid::operator() (double _x, double _y, double _z) const {
             return (pow(_x - center.x, 2) / pow(q, 2)
diff --git a/spheroid.hpp b/spheroid.hpp
index ca74894..df84664 100644
--- a/spheroid.hpp
+++ b/spheroid.hpp
@@ -7,6 +7,7 @@
 #include <cmath>
 #include "Implicit.hpp"
 #include "common_structures.hpp"
+#include "PerlinNoise.hpp"
 
 const double PI = 3.141592653589793;
 
@@ -19,6 +20,8 @@ class Spheroid : public ImplicitSurface {
         void set_stiffness(size_t _stiffness);
         void check_horizontal_plan_collision(double& height);
         void check_vertical_plan_collision(double& abscissa);
+        void check_perlin_collision(PerlinNoise perlin);
+        Point getNormalVector() const { return normal_vector;}
         double operator() (double _x, double _y, double _z) const;
     private:
         /**
@@ -27,6 +30,7 @@ class Spheroid : public ImplicitSurface {
          * V is the volume. Extremely useful to have a constant volume in the
          * ball
         **/
+        Point normal_vector;
         double init_p, p, q;
         size_t stiffness;
         double V;