begin implementing polymorphism

src/object.hpp

@@ -0,0 +1,20 @@
+#ifndef __OBJECT_H_
+#define __OBJECT_H_
+
+#include <SFML/Graphics.hpp>
+
+class Object {
+protected:
+  double x, y;
+  const unsigned short radius;
+
+  sf::CircleShape appearance;
+
+protected:
+  Object(double x, double y, unsigned short radius);
+
+public:
+  virtual bool collide(const Object& other);
+};
+
+#endif // __OBJECT_H_

src/umwelt.hpp

@@ -0,0 +1,11 @@
+#ifndef __UMWELT_H_
+#define __UMWELT_H_
+
+#include <vector>
+#include "object.hpp"
+
+struct Umwelt {
+  std::vector<Object> objects;
+};
+
+#endif // __UMWELT_H_