aabb.h

#ifndef AABB_H
#define AABB_H

#include "rtweekend.h"

class aabb {
public:
	aabb(){}
	aabb(const point3& a, const point3& b) : minimum(a), maximum(b) {}

	point3 min() { return minimum; }
	point3 max() { return maximum; }

	bool hit(const ray& r, double t_min, double t_max) const;

	point3 minimum, maximum;
};

inline bool aabb::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 = (minimum[a] - r.origin()[a]) * invD;
		auto t1 = (maximum[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 // !AABB_H