// use phong shading model
Vec4d PhongMaterial::shade(
const RayIntersection& intersection,
const Light& light) const
{
// calculate diffuse part of the equation
Vec3d lightDirection = (light.position() - intersection.position()).normalize();
Vec3d diffuse = this->color() * std::max(dot(intersection.normal(), lightDirection), 0.d);
// calculate specular part
Vec3d viewDirection = intersection.ray().direction();
Vec3d reflection = reflect(lightDirection, intersection.normal());
Vec3d lightcolor = light.spectralIntensity() / 255;
Vec3d specular = ((mShininess + 2) / (2 * M_PI)) * SPECULAR_REFLECTION_DEGREE * pow(std::max(dot(reflection, viewDirection), 0.d), mShininess) * lightcolor;
// calculcate sum -> result
return Vec4d(diffuse + specular, 1);
}
DistributionSample
MirrorMaterial::sampleBxDF( RandomNumberGenerator & rng,
const RayIntersection & intersection ) const
{
// Perfect mirror - PDF if a Dirac delta function
DistributionSample sample;
sample.direction = mirror( intersection.fromDirection(),
intersection.normal );
sample.pdf_sample = DistributionSample::DIRAC_PDF_SAMPLE;
return sample;
}
Vec4d Raytracer::shade(const RayIntersection& intersection,
size_t depth) const
{
// This offset must be added to intersection points for further
// traced rays to avoid noise in the image
const Vec3d offset(intersection.normal() * Math::safetyEps());
Vec4d color(0,0,0,1);
std::shared_ptr<const Renderable> renderable = intersection.renderable();
std::shared_ptr<const Material> material = renderable->material();
for(size_t i=0;i <mScene->lights().size();++i)
{
const Light &light = *(mScene->lights()[i].get());
//Shadow ray from light to hit point.
const Vec3d L = (intersection.position() + offset) - light.position();
const Ray shadowRay(light.position(), L);
//Shade only if light in visible from intersection point.
if (!mScene->anyIntersection(shadowRay,L.length()))
color += material->shade(intersection,light);
}
// limit recursion depth
if (depth >= mMaxDepth)
return color;
Vec3d dir = reflect(intersection.ray().direction(), intersection.normal());
Ray reflectedRay(intersection.position() + offset, dir);
double reflectance = material->reflectance();
color = color * (1 - reflectance) + reflectance * trace(reflectedRay, depth - 1) + Vec4d(0.0,0.0,0.0,1.0);
return color;
}
void InspectionShader::shade( Scene & scene, RandomNumberGenerator & rng, RayIntersection & intersection )
{
RGBColor color( 0.0f, 0.0f, 0.0f );
const float index_in = intersection.ray.index_of_refraction;
const float index_out = intersection.material->index_of_refraction;
const Vector4 from_dir = intersection.fromDirection();
switch( property ) {
case FresnelDialectric:
{
Vector4 refracted = refract( from_dir, intersection.normal, index_in, index_out );
float fresnel = 1.0f;
if( refracted.magnitude() > 0.0001 ) {
fresnel = Fresnel::Dialectric::Unpolarized( dot( from_dir, intersection.normal ),
dot( refracted, intersection.normal.negated() ),
index_in,
index_out );
}
color = RGBColor( fresnel, fresnel, fresnel );
}
break;
case FresnelConductor:
{
float absorptionCoeff = 2.0; // FIXME: material specific
float fresnel = Fresnel::Conductor::Unpolarized( dot( from_dir, intersection.normal ), index_out, absorptionCoeff );
color = RGBColor( fresnel, fresnel, fresnel );
}
break;
case Normal:
{
auto shifted = add( scale( intersection.normal, 0.5 ),
Vector4( 0.5, 0.5, 0.5 ) );
color = RGBColor( shifted.x, shifted.y, shifted.z );
}
break;
case IndexOfRefraction:
{
float v = index_out / 3.0;
color = RGBColor( v, v, v );
}
break;
case TextureUVCoordinate:
{
color = RGBColor( intersection.u, intersection.v, 0.0 );
}
break;
default:
;
}
intersection.sample.color = color;
}
Vec4d Raytracer::shade(const RayIntersection &intersection,
size_t depth) const {
// This offset must be added to intersection points for further
// traced rays to avoid noise in the image
const Vec3d offset(intersection.normal() * Math::safetyEps());
Vec4d color(0, 0, 0, 1);
std::shared_ptr<const Renderable> renderable = intersection.renderable();
std::shared_ptr<const Material> material = renderable->material();
for (size_t i = 0; i < mScene->lights().size(); ++i) {
const Light &light = *(mScene->lights()[i].get());
//Shadow ray from light to hit point.
const Vec3d L = (intersection.position() + offset) - light.position();
const Ray shadowRay(light.position(), L);
//Shade only if light in visible from intersection point.
if (!mScene->anyIntersection(shadowRay, L.length()))
color += material->shade(intersection, light);
}
return color;
}
bool
Scene::closestIntersection(const Ray &ray,RayIntersection& intersection, double maxLambda) const
{
double closestLambda = maxLambda;
RayIntersection tmpIntersection;
RayIntersection closestIntersection;
bool hit(false);
for (size_t i=0;i<mRenderables.size();++i)
{
std::shared_ptr<Renderable> r = mRenderables[i];
if(r->closestIntersection(ray,closestLambda,tmpIntersection))
{
if(tmpIntersection.lambda() < closestLambda)
{
hit=true;
closestLambda = tmpIntersection.lambda();
closestIntersection = tmpIntersection;
}
}
}
intersection=closestIntersection;
return hit;
}
DistributionSample
RefractiveMaterial::sampleBxDF( RandomNumberGenerator & rng,
const RayIntersection & intersection ) const
{
// Perfect Fresnel refractor
DistributionSample sample;
const float index_in = intersection.ray.index_of_refraction;
const float index_out = index_of_refraction;
const Vector4 from_dir = intersection.fromDirection();
// FIXME: HACK - This assumes that if we hit the surface of an object with the same
// index of refraction as the material we're in, then we are moving back into
// free space. This might not be true if there are numerical errors tracing
// abutting objects of the same material type, or for objects that are intersecting.
if( index_out == index_in ) {
sample.new_index_of_refraction = 1.0f;
}
Vector4 refracted = refract( from_dir, intersection.normal, index_in, index_out );
float fresnel = 1.0f; // default to total internal reflection if refract() returns
// a zero length vector
if( refracted.magnitude() > 0.0001 ) {
fresnel = Fresnel::Dialectric::Unpolarized( dot( from_dir, intersection.normal ),
dot( refracted, intersection.normal.negated() ),
index_in,
index_out );
}
const float draw = rng.uniform01();
// Use RNG to choose whether to reflect or refract based on Fresnel coefficient.
// Random selection accounts for fresnel or 1-fresnel scale factor.
if( fresnel == 1.0f || draw < fresnel ) {
// Trace reflection (mirror ray scaled by fresnel or 1 for total internal reflection)
sample.direction = mirror( from_dir, intersection.normal );
// FIXME - How do we determine pdf_sample for total internal reflection?
sample.pdf_sample = fresnel;
sample.new_index_of_refraction = index_in;
}
else {
// Trace refraction (refracted ray scaled by 1-fresnel)
sample.direction = refracted;
sample.pdf_sample = 1.0 - fresnel;
sample.new_index_of_refraction = index_out;
}
return sample;
}
Vec4d CheckerMaterial::shade(const RayIntersection& intersection,
const Light& light) const
{
const Vec3d &uvw = intersection.uvw();
const bool left = (fmod(fabs(uvw[0]), 1/mTiles[0])
< (1/mTiles[0] / double(2)))
^ (uvw[0] < double(0));
const bool lower = (fmod(fabs(uvw[1]), 1/mTiles[1])
< (1/mTiles[1] / double(2)))
^ (uvw[1] < double(0));
if(left ^ lower)
return mMaterial1->shade(intersection, light);
else
return mMaterial2->shade(intersection, light);
}
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 );
}
}
Spectrum Path::computeLi( const vec2f &pFilm, const SceneData &i_scene, const Camera &i_camera, const Sampler &i_sampler, int i_depth )
{
Camera::CameraSample cameraSample;
cameraSample.pixelSample = pFilm + i_sampler.sample2D();
cameraSample.lensSample = i_sampler.sample2D();
Ray ray;
float weight = i_camera.generateRay( cameraSample, &ray );
// Radiance
Spectrum L = Spectrum( 0.0f );
// Importance
Spectrum beta = Spectrum( 1.0 );
for ( int bounces = 0;; bounces++ ) {
RayIntersection intersection;
bool foundIntersection = i_scene.intersect( ray, intersection );
float maxDepth = 5;
if ( !foundIntersection || bounces >= maxDepth ) {
break;
}
Spectrum Le = intersection.Le();
if ( Le.isBlack() )
{
// Direct illumination sampling
Spectrum Ld = beta * uniformSampleOneLight( intersection, i_sampler, i_scene );
L += Ld;
// BSDF Sampling
const shading::BSDF &bsdf = intersection.getBSDF();
const vec3f &surfacePosition = intersection.getSurfacePoint().pos;
vec3f woLocal = -intersection.worldToSurface( -intersection.dir );
vec3f wiLocal;
float pdf = 1.0;
const vec2f &bsdfSample = i_sampler.sample2D();
Spectrum f = bsdf.sampleF( woLocal, &wiLocal, bsdfSample, &pdf );
// No point of continuing if no color
if ( f.isBlack() || pdf == 0.0 ) {
break;
}
// Transform to world space
vec3f wiWorld = intersection.surfaceToWorld( wiLocal );
// Generate new ray
ray = Ray( surfacePosition, wiWorld );
beta *= ( f * absDot( wiWorld, intersection.getSurfacePoint().normal ) ) / pdf;
// Russian Roulette
if ( beta.y() < 1.0f && bounces > 3 ) {
float q = std::max( .05f, 1 - beta.maxComponentValue() );
if ( i_sampler.sample1D() > q ) {
beta /= ( 1.0 - q );
}
else {
break;
}
}
}
else {
L += beta * intersection.Le() / 50.0;
break;
}
}
return weight * L;
}
Spectrum Path::estimateDirectLighting( const RayIntersection i_intersection, RenderablePtr i_light, const Sampler &i_sampler, const SceneData &i_scene )
{
// Direct contribution
Spectrum Ld = Spectrum::black();
float lightPdf = 0.0f;
float surfacePdf = 0.0f;
vec3f wiWorld;
const vec3f &woWorld = -i_intersection.dir;
const vec3f &woLocal = i_intersection.worldToSurface( woWorld );
const vec3f &normal = i_intersection.getSurfacePoint().normal;
const shading::BSDF &bsdf = i_intersection.getBSDF();
/* ==================== */
/* Sample Light */
/* ==================== */
{
VisibilityTester visibilityTester;
const vec3f &uLight = i_sampler.sample3D();
Spectrum Li = i_light->sampleIncidenceRadiance( i_intersection, uLight, &wiWorld, &lightPdf, &visibilityTester );
// Convert to local (surface) coords
const vec3f &wiLocal = i_intersection.worldToSurface( wiWorld );
// Sample light
if ( !Li.isBlack() && lightPdf > 0.0f ) {
const Spectrum &f = bsdf.computeF( woLocal, wiLocal ) * absDot( wiWorld, normal );
surfacePdf = bsdf.pdf( woLocal, wiLocal );
if ( !f.isBlack() ) {
// Ray is in shadow
if ( visibilityTester.isOccluded( i_scene ) ) {
Li = Spectrum::black();
}
if ( !Li.isBlack() ) {
// Weight with MIS
float misWeight = powerHeuristic( lightPdf, surfacePdf );
Ld += ( Li * f * misWeight ) / lightPdf;
}
}
}
}
/* ==================== */
/* Sample BSDF */
/* ==================== */
{
const vec2f &uSurface = i_sampler.sample2D();
vec3f wiLocal;
const Spectrum &f = bsdf.sampleF( woLocal, &wiLocal, uSurface, &surfacePdf ) * absDot( wiWorld, normal );
if ( !f.isBlack() && surfacePdf > 0.0f ) {
// TODO computer light PDF
lightPdf = 0.0;
// No contribution, return
if ( lightPdf == 0.0 ) {
return Ld;
}
// Convert to local (surface) coords
vec3f wiWorld = i_intersection.surfaceToWorld( wiLocal );
const Ray bsdfRay = Ray( i_intersection.getSurfacePoint().pos, wiWorld );
RayIntersection lightIntersection;
bool foundIntersection = i_scene.intersect( bsdfRay, lightIntersection );
Spectrum Li = Spectrum::black();
if ( foundIntersection ) {
if ( lightIntersection.m_shapeId == i_light->getIdentifier() ) {
Li = i_light->computeRadiance( lightIntersection.getSurfacePoint(), wiWorld );
}
}
if ( !Li.isBlack() ) {
// Weight with MIS
float misWeight = powerHeuristic( lightPdf, surfacePdf );
Ld += ( Li * f * misWeight ) / surfacePdf;
}
}
}
return Ld;
}