/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* TRACE ALGORITHM * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
ngl::Colour Renderer::trace(ngl::Vec3 _from, ngl::Vec3 _direction, int depth)
{
// create vector that will store intersection values for parameter t in the primary ray
// a primary ray has a form like R = O + t * D where O is the origin vector, and D direction.
std::vector<double> intersections;
geo::Ray cam_ray(_from,_direction);
// iterate over objects in the scene and find intersections
for(unsigned int i = 0; i < m_scene->m_objects.size(); i++)
{
// each Shape subclass (Sphere, Plane...) has its own method for calculating intersections
intersections.push_back( m_scene->m_objects.at(i)->getIntersection(cam_ray));
}
// find closest object
int closest_index = getIndexClosest(intersections);
// if no intersections are found RETURN black =
if(closest_index == -1) {return ngl::Colour(0,0,0,1);}
// calculate pHit (position of the new intersection) and nHit (normal at hit point)
ngl::Vec3 pHit = _from + intersections.at(closest_index) * _direction;
ngl::Vec3 nHit = m_scene->m_objects.at(closest_index)->getNormalAt(pHit);
// calculate if we are inside or outside
bool inside = false;
if(_direction.dot(nHit) > 0)
{
nHit = -nHit;
inside = true;
}
float bias = 0.01;
// calculate if point is obscured or shadowed
bool isObscured = raycast(pHit + nHit * bias, closest_index);
// // // // // // // // // // // // //
// put all contributions together //
// // // // // // // // // // // // //
// is the object reflective or refractive???
if ((m_scene->m_objects.at(closest_index)->getMaterial()->isReflective() ||
m_scene->m_objects.at(closest_index)->getMaterial()->isRefractive()) &&
depth < m_max_depth)
{
ngl::Colour crfr(0,0,0,1);
ngl::Colour crfl(0,0,0,1);
// check whether it is REFLECTIVE
if (m_scene->m_objects.at(closest_index)->getMaterial()->isReflective())
{
// calculate reflection dir
float bias = 0.01;
ngl::Vec3 refl_dir = _direction - nHit * 2 * _direction.dot(nHit);
refl_dir.normalize();
// fire ray along reflection direction from hit point
crfl = trace(pHit + bias*nHit, refl_dir, depth+1);
}
// check whether it is REFRACTIVE
if (m_scene->m_objects.at(closest_index)->getMaterial()->isRefractive())
{
// calculate refrection dir (transmission ray)
float ior = m_scene->m_objects.at(closest_index)->getMaterial()->getIOR();
float eta = inside;
float bias = 0.01;
float cosi = -nHit.dot(_direction);
if (eta == true) // we are inside
{
eta = ior;
}
else // we are outside
{
eta = 1 / ior;
}
float k = 1 - eta * eta * (1 - cosi * cosi);
ngl::Vec3 refr_dir = _direction * eta + nHit * (eta * cosi - sqrt(k));
refr_dir.normalize();
crfr = trace(pHit - nHit * bias, refr_dir, depth+1);
}
ngl::Colour surfaceColor = m_scene->m_objects.at(closest_index)->getColour(pHit);
float cosineFactor = std::max(-nHit.dot(cam_ray.getDirection()),(float)0);
float attenuation;
ngl::Colour Ka(1,0,0.4,1);
ngl::Colour Kd;
ngl::Colour Ks;
float ambient_intensity = 0.05;
ngl::Colour ambient_contrib = Ka * surfaceColor * ambient_intensity;
ngl::Colour diffuse_contrib(0,0,0,1);
ngl::Colour specular_contrib(0,0,0,1);
for(unsigned int m = 0; m < m_scene->m_lights.size(); m++)
{
ngl::Vec3 v_distance = m_scene->m_lights.at(m)->m_pos - pHit;
float distance = v_distance.length();
float radius = 8;
attenuation = 1 - pow(distance/radius,2);
Kd = m_scene->m_lights.at(m)->m_diff_col;
Ks = m_scene->m_lights.at(m)->m_spec_col;
ngl::Vec3 L = m_scene->m_lights.at(m)->m_pos - pHit;
L.normalize();
ngl::Vec3 N = nHit;
ngl::Vec3 R = 2 * (L.dot(N) * N) - L;
R.normalize();
diffuse_contrib += (surfaceColor * (Kd * pow(std::max(L.dot(N),(float)0),2) * m_scene->m_lights.at(m)->m_diff_int))*attenuation;
specular_contrib += ((Ks * pow(std::max(R.dot(-_direction),(float)0),900)*400 * m_scene->m_lights.at(m)->m_spec_int))*attenuation;
}
specular_contrib.clamp(0,0.8);
ngl::Colour s01 = crfl * m_scene->m_objects.at(closest_index)->getMaterial()->getReflIntensity();
ngl::Colour s02 = crfr * m_scene->m_objects.at(closest_index)->getMaterial()->getTransparency();
ngl::Colour s03 = s01 + s02;
ngl::Colour diffuseColor = m_scene->m_objects.at(closest_index)->getColour(pHit) * cosineFactor * m_scene->m_objects.at(closest_index)->getMaterial()->getDiffuseIntensity();
// Do PHONG MODEL calculations stuff. By now I keep it VERY VERY simple
ngl::Colour outRadiance = diffuseColor + s03 + specular_contrib + ambient_contrib;
outRadiance.clamp(0,1);
return isObscured ? outRadiance * 0.7f : outRadiance;
}
// if it is not REFLECTIVE nor REFRACTIVE
else
{
ngl::Colour surfaceColor = m_scene->m_objects.at(closest_index)->getColour(pHit);
float attenuation;
ngl::Colour Ka(1,0,0.4,1);
ngl::Colour Kd;
ngl::Colour Ks;
float ambient_intensity = 0.05;
ngl::Colour ambient_contrib = Ka * surfaceColor * ambient_intensity;
ngl::Colour diffuse_contrib(0,0,0,1);
ngl::Colour specular_contrib(0,0,0,1);
for(unsigned int m = 0; m < m_scene->m_lights.size(); m++)
{
ngl::Vec3 v_distance = m_scene->m_lights.at(m)->m_pos - pHit;
float distance = v_distance.length();
float radius = 8;
attenuation = 1 - pow(distance/radius,2);
Kd = m_scene->m_lights.at(m)->m_diff_col;
Ks = m_scene->m_lights.at(m)->m_spec_col;
ngl::Vec3 L = m_scene->m_lights.at(m)->m_pos - pHit;
L.normalize();
ngl::Vec3 N = nHit;
ngl::Vec3 R = 2 * (L.dot(N) * N) - L;
R.normalize();
float spec_hardness = m_scene->m_objects.at(closest_index)->getMaterial()->m_spec_hardness;
diffuse_contrib += (surfaceColor * (Kd * pow(std::max(L.dot(N),(float)0),2) * m_scene->m_lights.at(m)->m_diff_int))*attenuation;
specular_contrib += ((Ks * pow(std::max(R.dot(-_direction),(float)0),spec_hardness) * m_scene->m_lights.at(m)->m_spec_int))*attenuation;
}
diffuse_contrib.clamp(0,1);
specular_contrib.clamp(0,1);
ngl::Colour outRadiance = diffuse_contrib + specular_contrib + ambient_contrib;
outRadiance.clamp(0,1);
return isObscured ? outRadiance * 0.7f : outRadiance;
}
}
void BasicDiffuseSpecularShader::shade( Scene & scene, RandomNumberGenerator & rng, RayIntersection & intersection )
{
RGBColor diffuse_contrib( 0.0, 0.0, 0.0 );
RGBColor specular_contrib( 0.0, 0.0, 0.0 );
RGBColor direct_contrib( 0.0, 0.0, 0.0 );
Ray new_ray;
RayIntersection new_intersection;
new_intersection.min_distance = 0.01;
Vector4 offset( 0.0, 0.0, 0.0 );
//offset = scale( intersection.normal, 0.01 ); // NOTE - Seems to help
new_ray.origin = add( intersection.position, offset );
new_ray.depth = intersection.ray.depth + 1;
const unsigned char max_depth = 5;
//const unsigned char max_depth = 4;
//const unsigned char max_depth = 3;
//const unsigned char max_depth = 2;
Vector4 from_dir = intersection.fromDirection();
// Asserts
intersection.normal.assertIsUnity();
intersection.normal.assertIsDirection();
// Direct lighting
//
// Area lights
//for( Traceable * traceable : scene.lights ) {
// // TODO - sample lights
//}
// Point lights
for( const PointLight & light : scene.point_lights ) {
Vector4 to_light = subtract( light.position, intersection.position );
float dist_sq_to_light = to_light.magnitude_sq();
Vector4 direction = to_light.normalized();
direction.makeDirection();
// Shoot a ray toward the light to see if we are in shadow
Ray shadow_ray( intersection.position, direction );
RayIntersection shadow_isect;
shadow_isect.min_distance = 0.01;
if( scene.intersect( shadow_ray, shadow_isect )
&& sq(shadow_isect.distance) < dist_sq_to_light ) {
continue;
}
// Not in shadow
float cos_r_n = fabs( dot( direction, intersection.normal ) );
RGBColor color = light.band_power;
color.scale(cos_r_n);
color.scale(1.0f / to_light.magnitude_sq()); // distance falloff
// TODO: use actual material parameters properly so we can get specular here, too
if( intersection.material )
direct_contrib.accum( mult( color, intersection.material->diffuse ) );
else
direct_contrib.accum( color );
}
// TODO - How best should we choose between diffuse and specular?
// FIXME: Should I scale by the cosine for a perfect reflector?
if( intersection.ray.depth < max_depth ) {
const float diffuse_chance = 0.9;
float diff_spec_select = rng.uniform01();
if( intersection.material->perfect_reflector
|| intersection.material->perfect_refractor ) {
auto sample = intersection.material->sampleBxDF( rng, intersection );
new_ray.direction = sample.direction;
new_ray.index_of_refraction = sample.new_index_of_refraction;
if( scene.intersect( new_ray, new_intersection ) ) {
if( new_intersection.distance != FLT_MAX ) {
shade( scene, rng, new_intersection );
}
specular_contrib.accum( new_intersection.sample.color );
}
}
else if( diff_spec_select < diffuse_chance ) {
// Diffuse
rng.uniformSurfaceUnitHalfSphere( intersection.normal, new_ray.direction );
new_ray.direction.makeDirection();
if( scene.intersect( new_ray, new_intersection ) ) {
if( new_intersection.distance != FLT_MAX )
shade( scene, rng, new_intersection );
float cos_r_n = dot( new_ray.direction, intersection.normal );
new_intersection.sample.color.scale( cos_r_n );
diffuse_contrib.accum( new_intersection.sample.color );
}
}
else {
// Specular
// TODO - sample the specular lobe, not just the mirror direction
new_ray.direction = mirror( from_dir, intersection.normal );
new_ray.direction.makeDirection();
if( scene.intersect( new_ray, new_intersection ) ) {
if( new_intersection.distance != FLT_MAX )
shade( scene, rng, new_intersection );
float cos_r_n = dot( new_ray.direction, intersection.normal );
new_intersection.sample.color.scale( cos_r_n );
specular_contrib.accum( new_intersection.sample.color );
}
}
}
if( intersection.material ) {
intersection.sample.color = mult( diffuse_contrib, intersection.material->diffuse );
intersection.sample.color.accum( mult( specular_contrib, intersection.material->specular ) );
intersection.sample.color.accum( intersection.material->emittance );
intersection.sample.color.accum( direct_contrib );
}
else {
intersection.sample.color = diffuse_contrib;
intersection.sample.color.accum( direct_contrib );
}
}
