main.cpp

    // for all pixels of window
    for (int y = height_half_neg; y < height_half; ++y) {
      for (int x = width_half_neg; x < width_half; ++x) {
        Pixel p(x+width_half, y+height_half);

                // pseudo-camera-model:
                // by setting the camera origin at z=+focal_length, projecting
                // the vector at z=-focal_length results in the image plane being at
                // [0,0,0]
                camera_ray = Ray( math3d::point(0.,0.,focal_length),
                                  math3d::vector(x,y,-focal_length));

        // compute color for pixel
        std::shared_ptr<CRDS> intersection = m_scene->getNearestIntersection(camera_ray);
        if (intersection->hit == 1)
        {
          Ray camera_ray_t = Ray(
                intersection->shape->getInverseTransformation()
                      * camera_ray.origin,
                intersection->shape->getInverseTransformation()
                      * camera_ray.dir
                                );
          //camera_ray_t = camera_ray;   // ???
          math3d::point intersection_point = math3d::point(
                   camera_ray_t.origin[0]+intersection->t*camera_ray_t.dir[0],
                   camera_ray_t.origin[1]+intersection->t*camera_ray_t.dir[1],
                   camera_ray_t.origin[2]+intersection->t*camera_ray_t.dir[2]
                                             );
          intersection_point = intersection->shape->getTransformation()
                               * intersection_point;
                                      // ???
          Color temp_color = intersection->shape->getColor(intersection_point, m_scene);
          p.color = temp_color;
        } else {
          p.color = Color(0., 0., 0.);
        }

        window.write(p); // write pixel to output window
        image.write(p);  // write pixel to image writer
      }
    }