text: #include "atkui/framework.h"
  
  using glm::vec3;
  
  class Sphere2D : public atkui::Framework {
   public:
    Sphere2D() : atkui::Framework(atkui::Orthographic) {
    }
  
    virtual void scene() {
      // colors are RGB triplets in range [0,1]
      setColor(vec3(0,1,0));
  
      // draw a sphere at center of screen
      double x = width() * 0.5;
      double y = height() * 0.5;
      double radius = 100; 
      drawSphere(vec3(x,y,0), radius);
  
      // draw a sphere behind the big sphere
      setColor(vec3(1, 0, 0));
  
      double behindRadius = 120;
      drawSphere(vec3(x, y, -50), behindRadius);
    }
  };
  
  int main(int argc, char** argv)
  {
    Sphere2D viewer;
  
    // run simply closes the viewer?
    viewer.run();
    return 0;
  }
  