From 681fa9c8230a418457f9df967687da6665d51829 Mon Sep 17 00:00:00 2001
From: Miguel Angel <sonofgrendel@gmail.com>
Date: Sat, 7 Jan 2017 21:42:50 -0400
Subject: [PATCH] Reflective materials have lightning now.

---
 main.cpp        |  4 ++--
 path_tracer.cpp | 29 +++++++++++++++++------------
 2 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/main.cpp b/main.cpp
index 02d3895..a6ac8e0 100644
--- a/main.cpp
+++ b/main.cpp
@@ -264,8 +264,8 @@ static void scene_2(vector<Figure *> & vf, vector<Light *> & vl, mat4x4 & i_mode
   vf.push_back(static_cast<Figure *>(p));
 
   s = new Sphere(-0.5f, -0.5f, -1.5f, 0.5f);
-  s->m_mat.m_diffuse = vec3(1.0f, 1.0f, 0.0f);
-  s->m_mat.m_rho = 0.9f;
+  s->m_mat.m_diffuse = vec3(1.0f);
+  s->m_mat.m_rho = 0.4f;
   vf.push_back(static_cast<Figure *>(s));
 
   s = new Sphere(-0.5f, -0.5f, 0.6f, 0.5f);
diff --git a/path_tracer.cpp b/path_tracer.cpp
index c3b325d..7374db8 100644
--- a/path_tracer.cpp
+++ b/path_tracer.cpp
@@ -9,6 +9,8 @@ using namespace glm;
 
 PathTracer::~PathTracer() { }
 
+static const float PDF = (1.0f / (2.0f * pi<float>()));
+
 vec3 PathTracer::trace_ray(Ray & r, vector<Figure *> & v_figures, vector<Light *> & v_lights, unsigned int rec_level) const {
   float t, _t;
   Figure * _f;
@@ -35,7 +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 && _f->m_mat.m_rho == 0.0f) {
+    if( !_f->m_mat.m_refract) {
       // Calculate the direct lighting.
       for (size_t l = 0; l < v_lights.size(); l++) {
 	// For every light source
@@ -62,30 +64,33 @@ vec3 PathTracer::trace_ray(Ray & r, vector<Figure *> & v_figures, vector<Light *
 	sample = sample_hemisphere(r1, r2);
 	rotate_sample(sample, n);
 	rr = Ray(normalize(sample), i_pos + (sample * BIAS));
-	ind_color += r1 * trace_ray(rr, v_figures, v_lights, rec_level + 1) / (1.0f / (2.0f * pi<float>()));
+	ind_color += r1 * trace_ray(rr, v_figures, v_lights, rec_level + 1) / PDF;
       }
 
       color += ((dir_diff_color + ind_color) * (_f->m_mat.m_diffuse / pi<float>())) + dir_spec_color;
 
-    } else {
-      // If the material has reflection/transmission enabled.
-      // Calculate the Fresnel term if the surface is refracting.
-      if (_f->m_mat.m_refract)
-	kr = fresnel(r.m_direction, n, r.m_ref_index, _f->m_mat.m_ref_index);
-      else
-	kr = _f->m_mat.m_rho;
+      // Determine the specular reflection color.
+      if (_f->m_mat.m_rho > 0.0f && rec_level < MAX_RECURSION) {
+	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 >= MAX_RECURSION)
+	return vec3(0.0f);
 
-      // Determinte the specular reflection color.
+    } 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);
+
+      // Determine the specular reflection color.
       if (kr > 0.0f && rec_level < MAX_RECURSION) {
 	rr = Ray(normalize(reflect(r.m_direction, n)), i_pos + n * BIAS);
-	color += _f->m_mat.m_rho * kr * trace_ray(rr, v_figures, v_lights, rec_level + 1);
+	color += kr * trace_ray(rr, v_figures, v_lights, rec_level + 1);
       } else if (rec_level >= MAX_RECURSION)
 	return vec3(0.0f);
 
       // Determine the transmission color.
       if (_f->m_mat.m_refract && kr < 1.0f && rec_level < MAX_RECURSION) {
 	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 - _f->m_mat.m_rho) * (1.0f - kr) * trace_ray(rr, v_figures, v_lights, rec_level + 1);
+	color += (1.0f - kr) * trace_ray(rr, v_figures, v_lights, rec_level + 1);
       } else if (rec_level >= MAX_RECURSION)
 	return vec3(0.0f);