std::pair< T, T > intersection( const ray<T,2u>& ray, const circle<T>& circle )
{
// check for no intersection
const T a = dot( ray.direction(), ray.direction() );
const T b = T(2.) * sum( ray.direction() * ( ray.source() - circle.center() ) );
const T c = dot( circle.center(), circle.center() )
+ dot( ray.source(), ray.source() )
- T(2.) * dot( ray.source(), circle.center() )
- sqr( circle.radius() );
return solve_quadratic_equation(a,b,c);
}
bool sphere::hit(const ray& r, float t_min, float t_max, hit_record& rec) const
{
vec3 oc = r.origin() - center;
float v2 = dot(r.direction(), r.direction());
float voc = dot(oc, r.direction());
// 判別式.
float discriminant = voc * voc - v2 * (dot(oc, oc) - radius*radius);
if (discriminant > 0) {
// 手前.
float temp = (-voc - sqrt(discriminant)) / v2;
if (temp < t_max && temp > t_min) {
rec.t = temp;
rec.p = r.org + rec.t * r.dir;
rec.normal = (rec.p - center);
rec.normal.noramlize();
getUV(rec.u, rec.v, rec.normal);
rec.mat_ptr = mat_ptr;
return true;
}
// 奥.
temp = (-voc + sqrt(discriminant)) / v2;
if (temp < t_max && temp > t_min) {
rec.t = temp;
rec.p = r.org + rec.t * r.dir;
rec.normal = (rec.p - center) / radius;
rec.normal.noramlize();
getUV(rec.u, rec.v, rec.normal);
rec.mat_ptr = mat_ptr;
return true;
}
}
return false;
}
bool yz_rect::hit(const ray& r, double t_min, double t_max, hit_record& rec) const {
double t = (k - r.origin().x()) / r.direction().x();
if (t<t_min || t>t_max) return false;
double y = r.origin().y() + t*r.direction().y();
double z = r.origin().z() + t*r.direction().z();
if (y<y0 || y>y1 || z<z0 || z>z1) return false;
rec.u = (y - y0) / (y1 - y0);
rec.v = (z - z0) / (z1 - z0);
rec.t = t;
rec.mat_ptr = mat_ptr;
rec.point = r.point_at_parameter(t);
rec.normal = vec3(1.0, 0.0, 0.0);
return true;
}
vec3 color(const ray& r, surface* world, int depth) {
hit_record rec;
if (world->hit(r, 0.001, DBL_MAX, rec)) {
ray scattered;
vec3 attenuation;
if (depth < MAXDEPTH &&
rec.mat_ptr->scatter(r, rec, attenuation, scattered)) {
return attenuation*color(scattered, world, depth+1);
} else {
return vec3(0, 0, 0);
}
} else {
vec3 unit_direction = unit_vector(r.direction());
double t = 0.5*(unit_direction.y() + 1.0);
return (1.0 - t)*vec3(1.0, 1.0, 1.0) + t*vec3(0.5, 0.7, 1.0);
}
}
static hdr_color
do_shade(scene const& scene, ray const& ray, shading_policy const& policy,
unsigned depth, double importance, sampler_prng_engine& prng)
{
if (!should_continue(depth, importance, policy))
return policy.background;
boost::optional<scene::intersection> i = scene.intersect_solid(ray);
if (!i)
return policy.background;
hdr_color result = i->texture();
for (light const& l : scene.lights()) {
vector3 const light_dir{l.get_source() - i->position()};
if (auto obstacle = scene.intersect_solid({i->position(), light_dir}))
if ((obstacle->position() - i->position()).squaredNorm() <
(l.get_source() - i->position()).squaredNorm())
continue; // Obstacle blocks direct path from light to solid
result = blend_light(
i->solid().material(), result, i->normal(), l.color(), light_dir
);
}
unit3 const perfect_reflection_dir = reflect(ray.direction(), i->normal());
unit3 const reflection_dir = cos_lobe_perturb(
perfect_reflection_dir,
i->solid().material().specular_exponent(),
prng
);
oxatrace::ray const reflected{i->position(), reflection_dir};
double const reflection_importance = i->solid().material().reflectance();
hdr_color const reflection = do_shade(
scene, reflected, policy, depth + 1, reflection_importance * importance,
prng
);
result = blend_reflection(i->solid().material(), result, reflection);
return result;
}
vec3 color(const ray& r, hitable *world, int depth)
{
hit_record rec;
if (world->hit(r,0.001f, 10000, rec)) {
ray scattered;
vec3 attenuation;
if (depth < 10 && rec.mat_ptr->scatter(r, rec, attenuation, scattered)) {
return attenuation * color(scattered, world, depth + 1);
}
else {
// ‰e.
return vec3(0,0,0);
}
}
else {
// ‹ó.
vec3 unit_direction = unit_vector(r.direction());
float t = 0.5 * (unit_direction.y() + 1.0);
return (1.0 - t) * vec3(1.0, 1.0, 1.0) + t * vec3(0.5, 0.7, 1.0);
}
}
ray(const ray<T,Dim>& r)
: m_src( r.source() ), m_dir( r.direction() ) { }
