aabb.h

#ifndef AABB_H
#define AABB_H

#include "utils.h"
#include "ray.h"
#include "vec3.h"

struct aabb {
    aabb() {}
    aabb(const point3& a, const point3& b) {minimum = a; maximum = b;}
    point3 minimum, maximum;
    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 invD = 1.0f/r.direction()[a];
            auto t0 = (min()[a] - r.origin()[a])*invD, t1 = (max()[a] - r.origin()[a])*invD;
            if (invD < 0.0f) std::swap(t0, t1);
            t_min = t0 > t_min ? t0 : t_min, t_max = t1 < t_max ? t1 : t_max;
            if (t_max <= t_min) return false;
        }
        return true;
    }
};

aabb surrounding_box(aabb box0, aabb box1) {
    point3 small(fmin(box0.min().x(), box1.min().x()), fmin(box0.min().y(), box1.min().y()), fmin(box0.min().z(), box1.min().z()));
    point3 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);
}

#endif