Added presentations from EVI 2017

EVI - 2017/EVI 21/EVIray/path_tracer.cpp

@@ -0,0 +1,159 @@
+#include <limits>
+
+#include <glm/gtc/constants.hpp>
+
+#include "path_tracer.hpp"
+#include "sampling.hpp"
+#include "area_light.hpp"
+
+using std::numeric_limits;
+using namespace glm;
+
+PathTracer::~PathTracer() { }
+
+vec3 PathTracer::trace_ray(Ray & r, Scene * s, unsigned int rec_level) const {
+  float t, _t;
+  Figure * _f;
+  vec3 n, color, i_pos, ref, sample, dir_diff_color, dir_spec_color, ind_color, amb_color;
+  Ray mv_r, sr, rr;
+  bool vis, is_area_light = false;
+  float kr, r1, r2;
+  AreaLight * al;
+
+  t = numeric_limits<float>::max();
+  _f = NULL;
+
+  // Find the closest intersecting surface.
+  for (size_t f = 0; f < s->m_figures.size(); f++) {
+    if (s->m_figures[f]->intersect(r, _t) && _t < t) {
+      t = _t;
+      _f = s->m_figures[f];
+    }
+  }
+
+  // If this ray intersects something:
+  if (_f != NULL) {
+    // Take the intersection point and the normal of the surface at that point.
+    i_pos = r.m_origin + (t * r.m_direction);
+    n = _f->normal_at_int(r, t);
+
+    is_area_light = false;
+    // Check if the object is an area light;
+    for (vector<Light *>::iterator it = s->m_lights.begin(); it != s->m_lights.end(); it++) {
+      if ((*it)->light_type() == Light::AREA && static_cast<AreaLight *>(*it)->m_figure == _f)
+	is_area_light = true;
+    }
+
+    // If the object is an area light, return it's emission value.
+    if (is_area_light) {
+      return _f->m_mat->m_emission;
+
+    // Check if the material is not reflective/refractive.
+    } else if (!_f->m_mat->m_refract) {
+      // Calculate the direct lighting.
+      for (size_t l = 0; l < s->m_lights.size(); l++) {
+	// For every light source
+	vis = true;
+
+	if (s->m_lights[l]->light_type() == Light::INFINITESIMAL) {
+	  // Cast a shadow ray to determine visibility.
+	  sr = Ray(s->m_lights[l]->direction(i_pos), i_pos + (n * BIAS));
+
+	  for (size_t f = 0; f < s->m_figures.size(); f++) {
+	    if (s->m_figures[f]->intersect(sr, _t) && _t < s->m_lights[l]->distance(i_pos)) {
+	      vis = false;
+	      break;
+	    }
+	  }
+
+	// Evaluate the shading model accounting for visibility.
+	dir_diff_color += vis ? s->m_lights[l]->diffuse(n, r, i_pos, *_f->m_mat) : vec3(0.0f);
+	dir_spec_color += vis ? s->m_lights[l]->specular(n, r, i_pos, *_f->m_mat) : vec3(0.0f);
+
+	} else if (s->m_lights[l]->light_type() == Light::AREA) {
+	  // Cast a shadow ray towards a sample point on the surface of the light source.
+	  al = static_cast<AreaLight *>(s->m_lights[l]);
+	  al->sample_at_surface();
+	  sr = Ray(al->direction(i_pos), i_pos + (n * BIAS));
+
+	  for (size_t f = 0; f < s->m_figures.size(); f++) {
+	    // Avoid self-intersection with the light source.
+	    if (al->m_figure != s->m_figures[f]) {
+	      if (s->m_figures[f]->intersect(sr, _t) && _t < al->distance(i_pos)) {
+		vis = false;
+		break;
+	      }
+	    }
+	  }
+
+	  // Evaluate the shading model accounting for visibility.
+	  dir_diff_color += vis ? s->m_lights[l]->diffuse(n, r, i_pos, *_f->m_mat) : vec3(0.0f);
+	  dir_spec_color += vis ? s->m_lights[l]->specular(n, r, i_pos, *_f->m_mat) : vec3(0.0f);
+	}
+      }
+
+      // Calculate indirect lighting contribution.
+      if (rec_level < m_max_depth) {
+	r1 = random01();
+	r2 = random01();
+	sample = sample_hemisphere(r1, r2);
+	rotate_sample(sample, n);
+	rr = Ray(normalize(sample), i_pos + (sample * BIAS));
+	ind_color += r1 * trace_ray(rr, s, rec_level + 1) / PDF;
+      }
+
+      // Calculate environment light contribution
+      vis = true;
+
+      r1 = random01();
+      r2 = random01();
+      sample = sample_hemisphere(r1, r2);
+      rotate_sample(sample, n);
+      rr = Ray(normalize(sample), i_pos + (sample * BIAS));
+
+      // Cast a shadow ray to determine visibility.
+      for (size_t f = 0; f < s->m_figures.size(); f++) {
+	if (s->m_figures[f]->intersect(rr, _t)) {
+	  vis = false;
+	  break;
+	}
+      }
+
+      amb_color = vis ? s->m_env->get_color(rr) * max(dot(n, rr.m_direction), 0.0f) / PDF : vec3(0.0f);
+
+      // Add lighting.
+      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) {
+	rr = Ray(normalize(reflect(r.m_direction, n)), i_pos + n * BIAS);
+	color += _f->m_mat->m_rho * trace_ray(rr, s, 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);
+
+      // Determine the specular reflection color.
+      if (kr > 0.0f && rec_level < m_max_depth) {
+	rr = Ray(normalize(reflect(r.m_direction, n)), i_pos + n * BIAS);
+	color += kr * trace_ray(rr, s, rec_level + 1);
+      } else if (rec_level >= m_max_depth)
+	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);
+	color += (1.0f - kr) * trace_ray(rr, s, rec_level + 1);
+      } else if (rec_level >= m_max_depth)
+	  return vec3(0.0f);
+
+    }
+
+    // Return final color.
+    return _f->m_mat->m_emission + color;
+
+  } else
+    return s->m_env->get_color(r);
+}