diff --git a/disk.hpp b/disk.hpp
index feb01d7..4471e25 100644
--- a/disk.hpp
+++ b/disk.hpp
@@ -13,20 +13,11 @@ class Disk : public Plane {
 public:
   float m_radius;
   
-  Disk(): m_radius(1.0f) {
-    m_point = vec3(0.0f);
-    m_normal = vec3(0.0f, 1.0f, 0.0f);
-  }
+  Disk(BRDF * _brdf = NULL): Plane(_brdf), m_radius(1.0f) { }
 
-  Disk(float x, float y, float z, float nx, float ny, float nz, float _r): m_radius(_r) {
-    m_point = vec3(x, y, z);
-    m_normal = normalize(vec3(nx, ny, nz));
-  }
+  Disk(float x, float y, float z, float nx, float ny, float nz, float _r, BRDF * _brdf = NULL): Plane(x, y, z, nx, ny, nz, _brdf), m_radius(_r) { }
 
-  Disk(vec3 _p, vec3 _n, float _r): m_radius(_r) {
-    m_point = _p;
-    m_normal = normalize(_n);
-  }
+  Disk(vec3 _p, vec3 _n, float _r, BRDF * _brdf = NULL): Plane(_p, _n, _brdf), m_radius(_r) { }
 
   virtual ~Disk() { }
 
diff --git a/figure.hpp b/figure.hpp
index 23f7f66..b047978 100644
--- a/figure.hpp
+++ b/figure.hpp
@@ -11,9 +11,15 @@ using glm::vec3;
 
 class Figure {
 public:
-  Material m_mat;
+  Material * m_mat;
 
-  virtual ~Figure() { }
+  Figure(BRDF * brdf = NULL) {
+    m_mat = new Material(brdf);
+  }
+  
+  virtual ~Figure() {
+    delete m_mat;
+  }
 
   virtual bool intersect(Ray & r, float & t) const = 0;
   virtual vec3 normal_at_int(Ray & r, float & t) const = 0;
diff --git a/main.cpp b/main.cpp
index d2becff..469e5d7 100644
--- a/main.cpp
+++ b/main.cpp
@@ -292,56 +292,56 @@ void scene_1(vector<Figure *> & vf, vector<Light *> & vl, mat4x4 & i_model_view)
   DirectionalLight * l;
 
   s = new Sphere(1.0f, 1.0f, -2.0f, 0.5f);
-  s->m_mat.m_diffuse = vec3(1.0f, 0.0f, 0.0f);
+  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);
+  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);
+  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);
+  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);
+  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);
+  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;
+  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;
+  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;
+  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;
+  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;
+  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();
@@ -367,59 +367,59 @@ void scene_2(vector<Figure *> & vf, vector<Light *> & vl, mat4x4 & i_model_view)
   PointLight * l;
  
   s = new Sphere(0.2f, 0.0f, -0.75f, 0.25f);
-  s->m_mat.m_diffuse = vec3(1.0f);
-  s->m_mat.m_rho = 0.2f;
+  s->m_mat->m_diffuse = vec3(1.0f);
+  s->m_mat->m_rho = 0.2f;
   vf.push_back(static_cast<Figure *>(s));
 
   p = new Plane(vec3(0.0f, -1.0f, 0.0f), vec3(0.0f, 1.0f, 0.0f));
-  p->m_mat.m_diffuse = vec3(0.0f, 1.0f, 0.0f);
+  p->m_mat->m_diffuse = vec3(0.0f, 1.0f, 0.0f);
   vf.push_back(static_cast<Figure *>(p));
 
   p = new Plane(vec3(-2.0f, 0.0f, 0.0f), vec3(1.0f, 0.0f, 0.0f));
-  p->m_mat.m_diffuse = vec3(1.0f, 0.0f, 0.0f);
+  p->m_mat->m_diffuse = vec3(1.0f, 0.0f, 0.0f);
   vf.push_back(static_cast<Figure *>(p));
 
   p = new Plane(vec3(2.0f, 0.0f, 0.0f), vec3(-1.0f, 0.0f, 0.0f));
-  p->m_mat.m_diffuse = vec3(0.0f, 0.0f, 1.0f);
+  p->m_mat->m_diffuse = vec3(0.0f, 0.0f, 1.0f);
   vf.push_back(static_cast<Figure *>(p));
 
   p = new Plane(vec3(0.0f, 1.0f, 0.0f), vec3(0.0f, -1.0f, 0.0f));
-  p->m_mat.m_diffuse = vec3(0.0f, 1.0f, 1.0f);
+  p->m_mat->m_diffuse = vec3(0.0f, 1.0f, 1.0f);
   vf.push_back(static_cast<Figure *>(p));
 
   p = new Plane(vec3(0.0f, 0.0f, -2.0f), vec3(0.0f, 0.0f, 1.0f));
-  p->m_mat.m_diffuse = vec3(1.0f, 0.0f, 1.0f);
+  p->m_mat->m_diffuse = vec3(1.0f, 0.0f, 1.0f);
   vf.push_back(static_cast<Figure *>(p));
 
   p = new Plane(vec3(0.0f, 0.0f, 1.1f), vec3(0.0f, 0.0f, -1.0f));
-  p->m_mat.m_diffuse = vec3(1.0f, 1.0f, 0.0f);
+  p->m_mat->m_diffuse = vec3(1.0f, 1.0f, 0.0f);
   vf.push_back(static_cast<Figure *>(p));
 
   s = new Sphere(-0.5f, -0.5f, -1.5f, 0.5f);
-  s->m_mat.m_diffuse = vec3(0.0f);
-  s->m_mat.m_rho = 1.0f;
+  s->m_mat->m_diffuse = vec3(0.0f);
+  s->m_mat->m_rho = 1.0f;
   vf.push_back(static_cast<Figure *>(s));
 
   s = new Sphere(-0.5f, -0.5f, 0.6f, 0.5f);
-  s->m_mat.m_diffuse = vec3(1.0f, 1.0f, 0.0f);
-  s->m_mat.m_refract = true;
-  s->m_mat.m_ref_index = 1.33f;
+  s->m_mat->m_diffuse = vec3(1.0f, 1.0f, 0.0f);
+  s->m_mat->m_refract = true;
+  s->m_mat->m_ref_index = 1.33f;
   vf.push_back(static_cast<Figure *>(s));
 
   d = new Disk(vec3(-0.25f, 1.0f, -1.0f), vec3(1.0f, 0.0f, 0.0f), 0.25f);
-  d->m_mat.m_diffuse = vec3(1.0f);
+  d->m_mat->m_diffuse = vec3(1.0f);
   vf.push_back(static_cast<Figure *>(d));
 
   d = new Disk(vec3(0.25f, 1.0f, -1.0f), vec3(-1.0f, 0.0f, 0.0f), 0.25f);
-  d->m_mat.m_diffuse = vec3(1.0f);
+  d->m_mat->m_diffuse = vec3(1.0f);
   vf.push_back(static_cast<Figure *>(d));
 
   d = new Disk(vec3(0.0f, 1.0f, -1.25f), vec3(0.0f, 0.0f, 1.0f), 0.25f);
-  d->m_mat.m_diffuse = vec3(1.0f);
+  d->m_mat->m_diffuse = vec3(1.0f);
   vf.push_back(static_cast<Figure *>(d));
 
   d = new Disk(vec3(0.0f, 1.0f, -0.75f), vec3(0.0f, 0.0f, -1.0f), 0.25f);
-  d->m_mat.m_diffuse = vec3(1.0f);
+  d->m_mat->m_diffuse = vec3(1.0f);
   vf.push_back(static_cast<Figure *>(d));
 
   l = new PointLight();
@@ -438,35 +438,35 @@ void scene_3(vector<Figure *> & vf, vector<Light *> & vl, mat4x4 & i_model_view)
   vec3 up = cross(center - eye, left);
 
   s = new Sphere(0.0f, -0.15f, -2.0f, 1.0f);
-  s->m_mat.m_diffuse = vec3(1.0f, 0.5f, 0.0f);
-  s->m_mat.m_specular = vec3(0.3f);
-  s->m_mat.m_shininess = 5.0f;
-  s->m_mat.m_rho = 0.4f;
-  s->m_mat.m_refract = true;
-  s->m_mat.m_ref_index = 1.33f;
+  s->m_mat->m_diffuse = vec3(1.0f, 0.5f, 0.0f);
+  s->m_mat->m_specular = vec3(0.3f);
+  s->m_mat->m_shininess = 5.0f;
+  s->m_mat->m_rho = 0.4f;
+  s->m_mat->m_refract = true;
+  s->m_mat->m_ref_index = 1.33f;
   vf.push_back(static_cast<Figure *>(s));
 
   s = new Sphere(0.0f, -0.15f, -2.0f, 0.5f);
-  s->m_mat.m_diffuse = vec3(0.0f);
-  s->m_mat.m_specular = vec3(0.0f);
-  s->m_mat.m_rho = 0.0f;
-  s->m_mat.m_refract = true;
-  s->m_mat.m_ref_index = 2.6f;
+  s->m_mat->m_diffuse = vec3(0.0f);
+  s->m_mat->m_specular = vec3(0.0f);
+  s->m_mat->m_rho = 0.0f;
+  s->m_mat->m_refract = true;
+  s->m_mat->m_ref_index = 2.6f;
   vf.push_back(static_cast<Figure *>(s));
 
   s = new Sphere(2.0f, 0.0f, -2.0f, 1.0f);
-  s->m_mat.m_diffuse = vec3(1.0f, 0.0f, 1.0f);
-  s->m_mat.m_rho = 1.0f;
+  s->m_mat->m_diffuse = vec3(1.0f, 0.0f, 1.0f);
+  s->m_mat->m_rho = 1.0f;
   vf.push_back(static_cast<Figure *>(s));
 
   s = new Sphere(-1.0f, 0.25f, -3.25f, 1.0f);
-  s->m_mat.m_diffuse = vec3(1.0f, 1.0f, 0.0f);
-  s->m_mat.m_shininess = 20.0f;
+  s->m_mat->m_diffuse = vec3(1.0f, 1.0f, 0.0f);
+  s->m_mat->m_shininess = 20.0f;
   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);
-  p->m_mat.m_specular = vec3(0.0f);
+  p->m_mat->m_diffuse = vec3(1.0f);
+  p->m_mat->m_specular = vec3(0.0f);
   vf.push_back(static_cast<Figure *>(p));
 
   l = new DirectionalLight();
@@ -500,11 +500,11 @@ void scene_4(vector<Figure *> & vf, vector<Light *> & vl, mat4x4 & i_model_view)
   Plane * p;
 
   s = new Sphere(0.0f, 0.0f, -2.0f, 1.0f);
-  s->m_mat.m_diffuse = vec3(1.0f, 1.0f, 0.0f);
+  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, -1.0f, 0.0f), vec3(0.0f, 1.0f, 0.0f));
-  p->m_mat.m_diffuse = vec3(1.0f);
-  p->m_mat.m_specular = vec3(0.0f);
+  p->m_mat->m_diffuse = vec3(1.0f);
+  p->m_mat->m_specular = vec3(0.0f);
   vf.push_back(static_cast<Figure *>(p));
 }
diff --git a/output.png b/output.png
index 357304b..5c19ea2 100644
Binary files a/output.png and b/output.png differ
diff --git a/path_tracer.cpp b/path_tracer.cpp
index 688bdf8..f0ccd17 100644
--- a/path_tracer.cpp
+++ b/path_tracer.cpp
@@ -37,7 +37,7 @@ vec3 PathTracer::trace_ray(Ray & r, vector<Figure *> & v_figures, vector<Light *
     n = _f->normal_at_int(r, t);
     
     // Check if the material is not reflective/refractive.
-    if (!_f->m_mat.m_refract) {
+    if (!_f->m_mat->m_refract) {
       // Calculate the direct lighting.
       for (size_t l = 0; l < v_lights.size(); l++) {
 	// For every light source
@@ -53,8 +53,8 @@ vec3 PathTracer::trace_ray(Ray & r, vector<Figure *> & v_figures, vector<Light *
 	}
 
 	// Evaluate the shading model accounting for visibility.
-	dir_diff_color += vis ? v_lights[l]->diffuse(n, r, i_pos, _f->m_mat) : vec3(0.0f);
-	dir_spec_color += vis ? v_lights[l]->specular(n, r, i_pos, _f->m_mat) : vec3(0.0f);
+	dir_diff_color += vis ? v_lights[l]->diffuse(n, r, i_pos, *_f->m_mat) : vec3(0.0f);
+	dir_spec_color += vis ? v_lights[l]->specular(n, r, i_pos, *_f->m_mat) : vec3(0.0f);
       }
 
       // Calculate indirect lighting contribution.
@@ -88,18 +88,18 @@ vec3 PathTracer::trace_ray(Ray & r, vector<Figure *> & v_figures, vector<Light *
 	amb_color = vis ? BCKG_COLOR * max(dot(n, rr.m_direction), 0.0f) / PDF : vec3(0.0f);
       }
       
-      color += ((dir_diff_color + ind_color + amb_color) * (_f->m_mat.m_diffuse / pi<float>())) + (_f->m_mat.m_specular * dir_spec_color);
+      color += ((dir_diff_color + ind_color + amb_color) * (_f->m_mat->m_diffuse / pi<float>())) + (_f->m_mat->m_specular * dir_spec_color);
 
       // Determine the specular reflection color.
-      if (_f->m_mat.m_rho > 0.0f && rec_level < m_max_depth) {
+      if (_f->m_mat->m_rho > 0.0f && rec_level < m_max_depth) {
 	rr = Ray(normalize(reflect(r.m_direction, n)), i_pos + n * BIAS);
-	color += _f->m_mat.m_rho * trace_ray(rr, v_figures, v_lights, rec_level + 1);
-      } else if (_f->m_mat.m_rho > 0.0f && rec_level >= m_max_depth)
+	color += _f->m_mat->m_rho * trace_ray(rr, v_figures, v_lights, rec_level + 1);
+      } else if (_f->m_mat->m_rho > 0.0f && rec_level >= m_max_depth)
 	  return vec3(0.0f);
 
     } else {
       // If the material has transmission enabled, calculate the Fresnel term.
-      kr = fresnel(r.m_direction, n, r.m_ref_index, _f->m_mat.m_ref_index);
+      kr = fresnel(r.m_direction, n, r.m_ref_index, _f->m_mat->m_ref_index);
 
       // Determine the specular reflection color.
       if (kr > 0.0f && rec_level < m_max_depth) {
@@ -109,8 +109,8 @@ vec3 PathTracer::trace_ray(Ray & r, vector<Figure *> & v_figures, vector<Light *
 	return vec3(0.0f);
 
       // Determine the transmission color.
-      if (_f->m_mat.m_refract && kr < 1.0f && rec_level < m_max_depth) {
-	rr = Ray(normalize(refract(r.m_direction, n, r.m_ref_index / _f->m_mat.m_ref_index)), i_pos - n * BIAS, _f->m_mat.m_ref_index);
+      if (_f->m_mat->m_refract && kr < 1.0f && rec_level < m_max_depth) {
+	rr = Ray(normalize(refract(r.m_direction, n, r.m_ref_index / _f->m_mat->m_ref_index)), i_pos - n * BIAS, _f->m_mat->m_ref_index);
 	color += (1.0f - kr) * trace_ray(rr, v_figures, v_lights, rec_level + 1);
       } else if (rec_level >= m_max_depth)
 	  return vec3(0.0f);
diff --git a/plane.hpp b/plane.hpp
index 5ac3baa..00e3ffa 100644
--- a/plane.hpp
+++ b/plane.hpp
@@ -14,11 +14,11 @@ public:
   vec3 m_point;
   vec3 m_normal;
   
-  Plane(): m_point(vec3(0.0f)), m_normal(0.0f, 0.0f, 1.0f) { }
+  Plane(BRDF * _brdf = NULL): Figure(_brdf), m_point(vec3(0.0f)), m_normal(vec3(0.0f, 0.0f, 1.0f)) { }
 
-  Plane(float x, float y, float z, float nx, float ny, float nz): m_point(vec3(x, y, z)), m_normal(normalize(vec3(nx, ny, nz))) { }
+  Plane(float x, float y, float z, float nx, float ny, float nz, BRDF * _brdf = NULL): Figure(_brdf), m_point(vec3(x, y, z)), m_normal(normalize(vec3(nx, ny, nz))) { }
 
-  Plane(vec3 _p, vec3 _n): m_point(_p), m_normal(normalize(_n)) { }
+  Plane(vec3 _p, vec3 _n, BRDF * _brdf = NULL): Figure(_brdf), m_point(_p), m_normal(normalize(_n)) { }
 
   virtual ~Plane() { }
 
diff --git a/sphere.hpp b/sphere.hpp
index 63092ea..555187e 100644
--- a/sphere.hpp
+++ b/sphere.hpp
@@ -13,11 +13,11 @@ public:
   vec3 m_center;
   float m_radius;
   
-  Sphere(): m_center(vec3(0.0f)), m_radius(0.5f) { }
+  Sphere(BRDF * _brdf = NULL): Figure(_brdf), m_center(vec3(0.0f)), m_radius(0.5f) { }
 
-  Sphere(float x, float y, float z, float r): m_center(vec3(x, y, z)), m_radius(r) { }
+  Sphere(float x, float y, float z, float r, BRDF * _brdf = NULL): Figure(_brdf), m_center(vec3(x, y, z)), m_radius(r) { }
 
-  Sphere(vec3 _c, float r): m_center(_c), m_radius(r) { }
+  Sphere(vec3 _c, float r, BRDF * _brdf = NULL): Figure(_brdf), m_center(_c), m_radius(r) { }
 
   virtual ~Sphere() { }
 
diff --git a/whitted_tracer.cpp b/whitted_tracer.cpp
index bae60bf..666cb11 100644
--- a/whitted_tracer.cpp
+++ b/whitted_tracer.cpp
@@ -35,7 +35,7 @@ vec3 WhittedTracer::trace_ray(Ray & r, vector<Figure *> & v_figures, vector<Ligh
     n = _f->normal_at_int(r, t);
     
     // Check if the material is not reflective/refractive.
-    if (!_f->m_mat.m_refract) {
+    if (!_f->m_mat->m_refract) {
       // Calculate the direct lighting.
       for (size_t l = 0; l < v_lights.size(); l++) {
 	// For every light source
@@ -51,22 +51,22 @@ vec3 WhittedTracer::trace_ray(Ray & r, vector<Figure *> & v_figures, vector<Ligh
 	}
 
 	// Evaluate the shading model accounting for visibility.
-	dir_diff_color += vis ? v_lights[l]->diffuse(n, r, i_pos, _f->m_mat) : vec3(0.0f);
-	dir_spec_color += vis ? v_lights[l]->specular(n, r, i_pos, _f->m_mat) : vec3(0.0f);
+	dir_diff_color += vis ? v_lights[l]->diffuse(n, r, i_pos, *_f->m_mat) : vec3(0.0f);
+	dir_spec_color += vis ? v_lights[l]->specular(n, r, i_pos, *_f->m_mat) : vec3(0.0f);
       }
       
-      color += (dir_diff_color * (_f->m_mat.m_diffuse / pi<float>())) + (_f->m_mat.m_specular * dir_spec_color);
+      color += (dir_diff_color * (_f->m_mat->m_diffuse / pi<float>())) + (_f->m_mat->m_specular * dir_spec_color);
 
       // Determine the specular reflection color.
-      if (_f->m_mat.m_rho > 0.0f && rec_level < m_max_depth) {
+      if (_f->m_mat->m_rho > 0.0f && rec_level < m_max_depth) {
 	rr = Ray(normalize(reflect(r.m_direction, n)), i_pos + n * BIAS);
-	color += _f->m_mat.m_rho * trace_ray(rr, v_figures, v_lights, rec_level + 1);
-      } else if (_f->m_mat.m_rho > 0.0f && rec_level >= m_max_depth)
+	color += _f->m_mat->m_rho * trace_ray(rr, v_figures, v_lights, rec_level + 1);
+      } else if (_f->m_mat->m_rho > 0.0f && rec_level >= m_max_depth)
 	  return vec3(0.0f);
 
     } else {
       // If the material has transmission enabled, calculate the Fresnel term.
-      kr = fresnel(r.m_direction, n, r.m_ref_index, _f->m_mat.m_ref_index);
+      kr = fresnel(r.m_direction, n, r.m_ref_index, _f->m_mat->m_ref_index);
 
       // Determine the specular reflection color.
       if (kr > 0.0f && rec_level < m_max_depth) {
@@ -76,8 +76,8 @@ vec3 WhittedTracer::trace_ray(Ray & r, vector<Figure *> & v_figures, vector<Ligh
 	return vec3(0.0f);
 
       // Determine the transmission color.
-      if (_f->m_mat.m_refract && kr < 1.0f && rec_level < m_max_depth) {
-	rr = Ray(normalize(refract(r.m_direction, n, r.m_ref_index / _f->m_mat.m_ref_index)), i_pos - n * BIAS, _f->m_mat.m_ref_index);
+      if (_f->m_mat->m_refract && kr < 1.0f && rec_level < m_max_depth) {
+	rr = Ray(normalize(refract(r.m_direction, n, r.m_ref_index / _f->m_mat->m_ref_index)), i_pos - n * BIAS, _f->m_mat->m_ref_index);
 	color += (1.0f - kr) * trace_ray(rr, v_figures, v_lights, rec_level + 1);
       } else if (rec_level >= m_max_depth)
 	  return vec3(0.0f);