aabb.hpp

#pragma once
 
#include <common.hpp>
#include <camera/ray.hpp>
#include <utils.hpp>
#include <math3d/vec3.hpp>
 
using namespace ptracey;
 
namespace ptracey {
 
class aabb {
public:
  aabb() {}
  aabb(const point3 &a, const point3 &b) {
    minimum = a;
    maximum = b;
  }
 
  point3 min() const { return minimum; }
  point3 max() const { return maximum; }
  bool hit(const ray &r, double t_min, double t_max) const {
    for (int a = 0; a < 3; a++) {
      auto t0 = fmin(
          (minimum[a] - r.origin()[a]) / r.direction()[a],
          (maximum[a] - r.origin()[a]) / r.direction()[a]);
      auto t1 = fmax(
          (minimum[a] - r.origin()[a]) / r.direction()[a],
          (maximum[a] - r.origin()[a]) / r.direction()[a]);
      t_min = fmax(t0, t_min);
      t_max = fmin(t1, t_max);
      if (t_max <= t_min)
        return false;
    }
    return true;
  }
  double area() const {
    auto a = maximum.x() - minimum.x();
    auto b = maximum.y() - minimum.y();
    auto c = maximum.z() - minimum.z();
    return 2 * (a * b + b * c + c * a);
  }
  int longest_axis() const {
    auto a = maximum.x() - minimum.x();
    auto b = maximum.y() - minimum.y();
    auto c = maximum.z() - minimum.z();
    if (a > b && a > c)
      return 0;
    else if (b > c)
      return 1;
    else
      return 2;
  }
 
public:
  point3 minimum;
  point3 maximum;
};
 
aabb surrounding_box(aabb box0, aabb box1) {
  vec3 small(fmin(box0.min().x(), box1.min().x()),
             fmin(box0.min().y(), box1.min().y()),
             fmin(box0.min().z(), box1.min().z()));
 
  vec3 big(fmax(box0.max().x(), box1.max().x()),
           fmax(box0.max().y(), box1.max().y()),
           fmax(box0.max().z(), box1.max().z()));
 
  return aabb(small, big);
}
}