toytracer/hittable.h

#ifndef HITTABLE_H
#define HITTABLE_H

#include <memory>

#include "ray.h"
#include "material.h"
#include "aabb.h"

class Material;

struct hit_record {
  Point3 p;
  Vec3 normal;
  std::shared_ptr<Material> mat_ptr;
  double t;
  double u;
  double v;
  bool front_face;

  inline void set_face_normal(const Ray& r, const Vec3& outward_normal) {
    front_face = dot(r.direction(), outward_normal) < 0;
    normal = front_face ? outward_normal : -outward_normal;
  }
};

class Hittable {
public:
  virtual bool hit(const Ray &r, double tmin, double tmax, hit_record &rec) const = 0;
  virtual bool bounding_box(double t0, double t1, Aabb& output_box) const = 0;
};

class Flip_face : public Hittable {
  public:
    Flip_face(std::shared_ptr<Hittable> p) : ptr(p) {}

  virtual bool hit(const Ray &r, double tmin, double tmax, hit_record &rec) const {
      if (!ptr->hit(r, tmin, tmax, rec))
          return false;

      rec.front_face = !rec.front_face;
      return true;
  }

  virtual bool bounding_box(double t0, double t1, Aabb& output_box) const {
      return ptr->bounding_box(t0, t1, output_box);
  }

  private:
    std::shared_ptr<Hittable> ptr;
};

#endif // HITTABLE_H