* Features [13/20]

 - [X] Perspective projection
 - [X] Ray-sphere intersection
 - [-] Ray-plane and derived intersections
   - [X] Ray-plane
   - [X] Ray-disk
   - [ ] Ray-triangle
   - [ ] Ray-box
 - [ ] Ray-mesh intersection
 - [ ] Octree mesh
 - [X] Directional lights
 - [X] Point lights
 - [X] Spotlights
 - [ ] Area lights
   - [ ] Sphere lights
   - [ ] Box/planar lights
 - [X] Phong shading
 - [X] Specular reflections
 - [X] Transmission
 - [X] Scene description input files (JSON)
 - [X] Indirect illumination
 - [ ] Glossy reflections
 - [X] Image based lighting
 - [X] HDR light probes for IBL
 - [X] Tone mapping
 - [ ] Texture mapping
 - [ ] Photon mapping

* Junk

#+BEGIN_SRC c++
  void scene_1(vector<Figure *> & vf, vector<Light *> & vl, Environment * & e, Camera * c) {
    Sphere * s;
    Plane * p;
    Disk * d;
    DirectionalLight * l;

    e = new Environment(NULL, false, vec3(0.7f, 0.4f, 0.05f));
    
    s = new Sphere(1.0f, 1.0f, -2.0f, 0.5f);
    s->m_mat->m_diffuse = vec3(1.0f, 0.0f, 0.0f);
    vf.push_back(static_cast<Figure *>(s));

    s = new Sphere(-1.0f, 1.0f, -2.0f, 0.5f);
    s->m_mat->m_diffuse = vec3(0.0f, 1.0f, 0.0f);
    vf.push_back(static_cast<Figure *>(s));

    s = new Sphere(1.0f, -1.0f, -2.0f, 0.5f);
    s->m_mat->m_diffuse = vec3(0.0f, 0.0f, 1.0f);
    vf.push_back(static_cast<Figure *>(s));

    s = new Sphere(-1.0f, -1.0f, -2.0f, 0.5f);
    s->m_mat->m_diffuse = vec3(1.0f, 0.0f, 1.0f);
    vf.push_back(static_cast<Figure *>(s));

    s = new Sphere(0.0f, 0.0f, -2.0f, 1.0f);
    s->m_mat->m_diffuse = vec3(1.0f, 1.0f, 0.0f);
    vf.push_back(static_cast<Figure *>(s));

    p = new Plane(vec3(0.0f, -1.5f, 0.0f), vec3(0.0f, 1.0f, 0.0f));
    p->m_mat->m_diffuse = vec3(1.0f, 0.5f, 0.4f);
    vf.push_back(static_cast<Figure *>(p));

    s = new Sphere(-1.5f, 0.0f, -2.0f, 0.5f);
    s->m_mat->m_diffuse = vec3(1.0f, 1.0f, 1.0f);
    s->m_mat->m_rho = 0.3f;
    vf.push_back(static_cast<Figure *>(s));

    s = new Sphere(1.5f, 0.0f, -2.0f, 0.5f);
    s->m_mat->m_diffuse = vec3(1.0f, 1.0f, 1.0f);
    s->m_mat->m_rho = 0.08f;
    s->m_mat->m_refract = true;
    s->m_mat->m_ref_index = 1.1f;
    vf.push_back(static_cast<Figure *>(s));

    s = new Sphere(0.0f, 1.5f, -2.0f, 0.5f);
    s->m_mat->m_diffuse = vec3(1.0f, 1.0f, 1.0f);
    s->m_mat->m_rho = 0.5f;
    vf.push_back(static_cast<Figure *>(s));

    s = new Sphere(0.0f, 0.0f, -1.0f, 0.25f);
    s->m_mat->m_diffuse = vec3(1.0f, 1.0f, 1.0f);
    s->m_mat->m_rho = 0.1f;
    vf.push_back(static_cast<Figure *>(s));

    d = new Disk(vec3(-0.0f, -0.0f, -0.5f), vec3(0.0f, 0.0f, 0.1f), 0.25f);
    d->m_mat->m_diffuse = vec3(1.0f, 0.0f, 0.0f);
    d->m_mat->m_rho = 0.3f;
    d->m_mat->m_refract = true;
    d->m_mat->m_ref_index = 1.33f;
    vf.push_back(static_cast<Figure *>(d));

    l = new DirectionalLight();
    l->m_position = normalize(vec3(1.0f, 1.0f, 1.0f));
    l->m_diffuse = vec3(0.0f, 1.0f, 1.0f);
    vl.push_back(static_cast<Light *>(l));

    l = new DirectionalLight();
    l->m_position = normalize(vec3(-1.0f, 1.0f, 1.0f));
    l->m_diffuse = vec3(1.0f, 1.0f, 0.0f);
    vl.push_back(static_cast<Light *>(l));

    l = new DirectionalLight();
    l->m_position = normalize(vec3(0.0f, 1.0f, -1.0f));
    l->m_diffuse = vec3(1.0f, 0.0f, 1.0f);
    vl.push_back(static_cast<Light *>(l));
  }
#+END_SRC