toytracer/hittable_list.h

#ifndef HITTABLE_LIST_H
#define HITTABLE_LIST_H

#include <memory>
#include <vector>

#include "hittable.h"
#include "bvh.h"

class Hittable_list : public Hittable {
public:
  Hittable_list() {}
  Hittable_list(std::shared_ptr<Hittable> object) { add(object); }

  void clear() { objects.clear(); }
  void add(std::shared_ptr<Hittable> object) { objects.push_back(object); }

  virtual bool hit(const Ray &r, double tmin, double tmax, hit_record &rec) const;
  bool bounding_box(double t0, double t1, Aabb& output_box) const;

  Bvh_node generate_bvh(double t0, double t1);

private:
  std::vector<std::shared_ptr<Hittable>> objects;

};

bool Hittable_list::hit(const Ray &r, double tmin, double tmax, hit_record &rec) const {
    hit_record temp_rec;
    bool hit_anything = false;
    auto closest_so_far = tmax;

    for (const auto& object : objects) {
       if (object->hit(r, tmin, closest_so_far, temp_rec)) {
           hit_anything = true;
           closest_so_far = temp_rec.t;
           rec = temp_rec;
       }
    }

    return hit_anything;
}

bool Hittable_list::bounding_box(double t0, double t1, Aabb& output_box) const {
    if (objects.empty()) return false;

    Aabb temp_box;
    bool first_box = true;

    for (const auto& object : objects) {
        if (!object->bounding_box(t0, t1, temp_box)) return false;
        output_box = first_box ? temp_box : surrounding_box(output_box, temp_box);
        first_box = false;
    }
    return true;
}

Bvh_node Hittable_list::generate_bvh(double t0, double t1) {
    return Bvh_node(objects, 0, objects.size(), t0, t1);
}

#endif // HITTABLE_LIST_H