moved Rendering to Display class

Display.cpp

@@ -0,0 +1,29 @@
+
+// make sure sfml is installed:
+// linux - sudo apt-get install libsfml-dev
+// windows - manual dl from https://www.sfml-dev.org/download.php
+#include <SFML/Graphics.hpp>
+#include <iostream>
+
+#include "Display.h"
+
+void Display::show()
+{
+    sf::RenderWindow window(sf::VideoMode(WIDTH, HEIGHT), "SFML works!");
+    sf::CircleShape shape(100.f);
+    shape.setFillColor(sf::Color::Green);
+
+    while (window.isOpen())
+    {
+        sf::Event event;
+        while (window.pollEvent(event))
+        {
+            if (event.type == sf::Event::Closed)
+                window.close();
+        }
+
+        window.clear();
+        window.draw(shape);
+        window.display();
+    }
+}

Display.h

@@ -0,0 +1,13 @@
+#pragma once
+
+#define WIDTH 800
+#define HEIGHT 600
+
+class Display
+{
+public:
+    void show();
+
+    // TODO:
+    // setData for used stuff... current triangle, all points, ladida...
+};