text: /*************************************************************************/
  /*  aabb.h                                                               */
  /*************************************************************************/
  /*                       This file is part of:                           */
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  /* Copyright (c) 2007-2020 Juan Linietsky, Ariel Manzur.                 */
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  #ifndef AABB_H
  #define AABB_H
  
  #include "core/math/math_defs.h"
  #include "core/math/plane.h"
  #include "core/math/vector3.h"
  
  /**
   * AABB / AABB (Axis Aligned Bounding Box)
   * This is implemented by a point (position) and the box size
   */
  
  class AABB {
  public:
  	Vector3 position;
  	Vector3 size;
  
  	real_t get_area() const; /// get area
  	_FORCE_INLINE_ bool has_no_area() const {
  
  		return (size.x <= 0 || size.y <= 0 || size.z <= 0);
  	}
  
  	_FORCE_INLINE_ bool has_no_surface() const {
  
  		return (size.x <= 0 && size.y <= 0 && size.z <= 0);
  	}
  
  	const Vector3 &get_position() const { return position; }
  	void set_position(const Vector3 &p_pos) { position = p_pos; }
  	const Vector3 &get_size() const { return size; }
  	void set_size(const Vector3 &p_size) { size = p_size; }
  
  	bool operator==(const AABB &p_rval) const;
  	bool operator!=(const AABB &p_rval) const;
  
  	bool is_equal_approx(const AABB &p_aabb) const;
  	_FORCE_INLINE_ bool intersects(const AABB &p_aabb) const; /// Both AABBs overlap
  	_FORCE_INLINE_ bool intersects_inclusive(const AABB &p_aabb) const; /// Both AABBs (or their faces) overlap
  	_FORCE_INLINE_ bool encloses(const AABB &p_aabb) const; /// p_aabb is completely inside this
  
  	AABB merge(const AABB &p_with) const;
  	void merge_with(const AABB &p_aabb); ///merge with another AABB
  	AABB intersection(const AABB &p_aabb) const; ///get box where two intersect, empty if no intersection occurs
  	bool intersects_segment(const Vector3 &p_from, const Vector3 &p_to, Vector3 *r_clip = NULL, Vector3 *r_normal = NULL) const;
  	bool intersects_ray(const Vector3 &p_from, const Vector3 &p_dir, Vector3 *r_clip = NULL, Vector3 *r_normal = NULL) const;
  	_FORCE_INLINE_ bool smits_intersect_ray(const Vector3 &p_from, const Vector3 &p_dir, real_t t0, real_t t1) const;
  
  	_FORCE_INLINE_ bool intersects_convex_shape(const Plane *p_planes, int p_plane_count, const Vector3 *p_points, int p_point_count) const;
  	_FORCE_INLINE_ bool inside_convex_shape(const Plane *p_planes, int p_plane_count) const;
  	bool intersects_plane(const Plane &p_plane) const;
  
  	_FORCE_INLINE_ bool has_point(const Vector3 &p_point) const;
  	_FORCE_INLINE_ Vector3 get_support(const Vector3 &p_normal) const;
  
  	Vector3 get_longest_axis() const;
  	int get_longest_axis_index() const;
  	_FORCE_INLINE_ real_t get_longest_axis_size() const;
  
  	Vector3 get_shortest_axis() const;
  	int get_shortest_axis_index() const;
  	_FORCE_INLINE_ real_t get_shortest_axis_size() const;
  
  	AABB grow(real_t p_by) const;
  	_FORCE_INLINE_ void grow_by(real_t p_amount);
  
  	void get_edge(int p_edge, Vector3 &r_from, Vector3 &r_to) const;
  	_FORCE_INLINE_ Vector3 get_endpoint(int p_point) const;
  
  	AABB expand(const Vector3 &p_vector) const;
  	_FORCE_INLINE_ void project_range_in_plane(const Plane &p_plane, real_t &r_min, real_t &r_max) const;
  	_FORCE_INLINE_ void expand_to(const Vector3 &p_vector); /** expand to contain a point if necessary */
  
  	_FORCE_INLINE_ AABB abs() const {
  		return AABB(Vector3(position.x + MIN(size.x, 0), position.y + MIN(size.y, 0), position.z + MIN(size.z, 0)), size.abs());
  	}
  
  	operator String() const;
  
  	_FORCE_INLINE_ AABB() {}
  	inline AABB(const Vector3 &p_pos, const Vector3 &p_size) :
  			position(p_pos),
  			size(p_size) {
  	}
  };
  
  inline bool AABB::intersects(const AABB &p_aabb) const {
  
  	if (position.x >= (p_aabb.position.x + p_aabb.size.x))
  		return false;
  	if ((position.x + size.x) <= p_aabb.position.x)
  		return false;
  	if (position.y >= (p_aabb.position.y + p_aabb.size.y))
  		return false;
  	if ((position.y + size.y) <= p_aabb.position.y)
  		return false;
  	if (position.z >= (p_aabb.position.z + p_aabb.size.z))
  		return false;
  	if ((position.z + size.z) <= p_aabb.position.z)
  		return false;
  
  	return true;
  }
  
  inline bool AABB::intersects_inclusive(const AABB &p_aabb) const {
  
  	if (position.x > (p_aabb.position.x + p_aabb.size.x))
  		return false;
  	if ((position.x + size.x) < p_aabb.position.x)
  		return false;
  	if (position.y > (p_aabb.position.y + p_aabb.size.y))
  		return false;
  	if ((position.y + size.y) < p_aabb.position.y)
  		return false;
  	if (position.z > (p_aabb.position.z + p_aabb.size.z))
  		return false;
  	if ((position.z + size.z) < p_aabb.position.z)
  		return false;
  
  	return true;
  }
  
  inline bool AABB::encloses(const AABB &p_aabb) const {
  
  	Vector3 src_min = position;
  	Vector3 src_max = position + size;
  	Vector3 dst_min = p_aabb.position;
  	Vector3 dst_max = p_aabb.position + p_aabb.size;
  
  	return (
  			(src_min.x <= dst_min.x) &&
  			(src_max.x > dst_max.x) &&
  			(src_min.y <= dst_min.y) &&
  			(src_max.y > dst_max.y) &&
  			(src_min.z <= dst_min.z) &&
  			(src_max.z > dst_max.z));
  }
  
  Vector3 AABB::get_support(const Vector3 &p_normal) const {
  
  	Vector3 half_extents = size * 0.5;
  	Vector3 ofs = position + half_extents;
  
  	return Vector3(
  				   (p_normal.x > 0) ? -half_extents.x : half_extents.x,
  				   (p_normal.y > 0) ? -half_extents.y : half_extents.y,
  				   (p_normal.z > 0) ? -half_extents.z : half_extents.z) +
  		   ofs;
  }
  
  Vector3 AABB::get_endpoint(int p_point) const {
  
  	switch (p_point) {
  		case 0: return Vector3(position.x, position.y, position.z);
  		case 1: return Vector3(position.x, position.y, position.z + size.z);
  		case 2: return Vector3(position.x, position.y + size.y, position.z);
  		case 3: return Vector3(position.x, position.y + size.y, position.z + size.z);
  		case 4: return Vector3(position.x + size.x, position.y, position.z);
  		case 5: return Vector3(position.x + size.x, position.y, position.z + size.z);
  		case 6: return Vector3(position.x + size.x, position.y + size.y, position.z);
  		case 7: return Vector3(position.x + size.x, position.y + size.y, position.z + size.z);
  	};
  
  	ERR_FAIL_V(Vector3());
  }
  
  bool AABB::intersects_convex_shape(const Plane *p_planes, int p_plane_count, const Vector3 *p_points, int p_point_count) const {
  
  	Vector3 half_extents = size * 0.5;
  	Vector3 ofs = position + half_extents;
  
  	for (int i = 0; i < p_plane_count; i++) {
  		const Plane &p = p_planes[i];
  		Vector3 point(
  				(p.normal.x > 0) ? -half_extents.x : half_extents.x,
  				(p.normal.y > 0) ? -half_extents.y : half_extents.y,
  				(p.normal.z > 0) ? -half_extents.z : half_extents.z);
  		point += ofs;
  		if (p.is_point_over(point))
  			return false;
  	}
  
  	// Make sure all points in the shape aren't fully separated from the AABB on
  	// each axis.
  	int bad_point_counts_positive[3] = { 0 };
  	int bad_point_counts_negative[3] = { 0 };
  
  	for (int k = 0; k < 3; k++) {
  
  		for (int i = 0; i < p_point_count; i++) {
  			if (p_points[i].coord[k] > ofs.coord[k] + half_extents.coord[k]) {
  				bad_point_counts_positive[k]++;
  			}
  			if (p_points[i].coord[k] < ofs.coord[k] - half_extents.coord[k]) {
  				bad_point_counts_negative[k]++;
  			}
  		}
  
  		if (bad_point_counts_negative[k] == p_point_count) {
  			return false;
  		}
  		if (bad_point_counts_positive[k] == p_point_count) {
  			return false;
  		}
  	}
  
  	return true;
  }
  
  bool AABB::inside_convex_shape(const Plane *p_planes, int p_plane_count) const {
  
  	Vector3 half_extents = size * 0.5;
  	Vector3 ofs = position + half_extents;
  
  	for (int i = 0; i < p_plane_count; i++) {
  		const Plane &p = p_planes[i];
  		Vector3 point(
  				(p.normal.x < 0) ? -half_extents.x : half_extents.x,
  				(p.normal.y < 0) ? -half_extents.y : half_extents.y,
  				(p.normal.z < 0) ? -half_extents.z : half_extents.z);
  		point += ofs;
  		if (p.is_point_over(point))
  			return false;
  	}
  
  	return true;
  }
  
  bool AABB::has_point(const Vector3 &p_point) const {
  
  	if (p_point.x < position.x)
  		return false;
  	if (p_point.y < position.y)
  		return false;
  	if (p_point.z < position.z)
  		return false;
  	if (p_point.x > position.x + size.x)
  		return false;
  	if (p_point.y > position.y + size.y)
  		return false;
  	if (p_point.z > position.z + size.z)
  		return false;
  
  	return true;
  }
  
  inline void AABB::expand_to(const Vector3 &p_vector) {
  
  	Vector3 begin = position;
  	Vector3 end = position + size;
  
  	if (p_vector.x < begin.x)
  		begin.x = p_vector.x;
  	if (p_vector.y < begin.y)
  		begin.y = p_vector.y;
  	if (p_vector.z < begin.z)
  		begin.z = p_vector.z;
  
  	if (p_vector.x > end.x)
  		end.x = p_vector.x;
  	if (p_vector.y > end.y)
  		end.y = p_vector.y;
  	if (p_vector.z > end.z)
  		end.z = p_vector.z;
  
  	position = begin;
  	size = end - begin;
  }
  
  void AABB::project_range_in_plane(const Plane &p_plane, real_t &r_min, real_t &r_max) const {
  
  	Vector3 half_extents(size.x * 0.5, size.y * 0.5, size.z * 0.5);
  	Vector3 center(position.x + half_extents.x, position.y + half_extents.y, position.z + half_extents.z);
  
  	real_t length = p_plane.normal.abs().dot(half_extents);
  	real_t distance = p_plane.distance_to(center);
  	r_min = distance - length;
  	r_max = distance + length;
  }
  
  inline real_t AABB::get_longest_axis_size() const {
  
  	real_t max_size = size.x;
  
  	if (size.y > max_size) {
  		max_size = size.y;
  	}
  
  	if (size.z > max_size) {
  		max_size = size.z;
  	}
  
  	return max_size;
  }
  
  inline real_t AABB::get_shortest_axis_size() const {
  
  	real_t max_size = size.x;
  
  	if (size.y < max_size) {
  		max_size = size.y;
  	}
  
  	if (size.z < max_size) {
  		max_size = size.z;
  	}
  
  	return max_size;
  }
  
  bool AABB::smits_intersect_ray(const Vector3 &p_from, const Vector3 &p_dir, real_t t0, real_t t1) const {
  
  	real_t divx = 1.0 / p_dir.x;
  	real_t divy = 1.0 / p_dir.y;
  	real_t divz = 1.0 / p_dir.z;
  
  	Vector3 upbound = position + size;
  	real_t tmin, tmax, tymin, tymax, tzmin, tzmax;
  	if (p_dir.x >= 0) {
  		tmin = (position.x - p_from.x) * divx;
  		tmax = (upbound.x - p_from.x) * divx;
  	} else {
  		tmin = (upbound.x - p_from.x) * divx;
  		tmax = (position.x - p_from.x) * divx;
  	}
  	if (p_dir.y >= 0) {
  		tymin = (position.y - p_from.y) * divy;
  		tymax = (upbound.y - p_from.y) * divy;
  	} else {
  		tymin = (upbound.y - p_from.y) * divy;
  		tymax = (position.y - p_from.y) * divy;
  	}
  	if ((tmin > tymax) || (tymin > tmax))
  		return false;
  	if (tymin > tmin)
  		tmin = tymin;
  	if (tymax < tmax)
  		tmax = tymax;
  	if (p_dir.z >= 0) {
  		tzmin = (position.z - p_from.z) * divz;
  		tzmax = (upbound.z - p_from.z) * divz;
  	} else {
  		tzmin = (upbound.z - p_from.z) * divz;
  		tzmax = (position.z - p_from.z) * divz;
  	}
  	if ((tmin > tzmax) || (tzmin > tmax))
  		return false;
  	if (tzmin > tmin)
  		tmin = tzmin;
  	if (tzmax < tmax)
  		tmax = tzmax;
  	return ((tmin < t1) && (tmax > t0));
  }
  
  void AABB::grow_by(real_t p_amount) {
  
  	position.x -= p_amount;
  	position.y -= p_amount;
  	position.z -= p_amount;
  	size.x += 2.0 * p_amount;
  	size.y += 2.0 * p_amount;
  	size.z += 2.0 * p_amount;
  }
  
  #endif // AABB_H
  