virtualx-engine/core/math/aabb.h

/*************************************************************************/
/*  aabb.h                                                               */
/*************************************************************************/
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/*                           GODOT ENGINE                                */
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/* Copyright (c) 2007-2015 Juan Linietsky, Ariel Manzur.                 */
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#ifndef AABB_H
#define AABB_H



#include "vector3.h"
#include "plane.h"
/**
 * AABB / AABB (Axis Aligned Bounding Box)
 * This is implemented by a point (pos) and the box size
 */



class AABB {
public:
	Vector3 pos;
	Vector3 size;

	float get_area() const; /// get area
	_FORCE_INLINE_ bool has_no_area() const {
	
		return (size.x<=CMP_EPSILON || size.y<=CMP_EPSILON  || size.z<=CMP_EPSILON);
	}

	_FORCE_INLINE_ bool has_no_surface() const {
	
		return (size.x<=CMP_EPSILON && size.y<=CMP_EPSILON  && size.z<=CMP_EPSILON);
	}
	
	const Vector3& get_pos() const { return pos; }
	void set_pos(const Vector3& p_pos) { pos=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;

	_FORCE_INLINE_ bool intersects(const AABB& p_aabb) const; /// Both AABBs 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 &from,const Vector3& p_dir, float t0, float t1) const;

	_FORCE_INLINE_ bool intersects_convex_shape(const Plane *p_plane, 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,float &r_min,float& r_max) const;
	_FORCE_INLINE_ void expand_to(const Vector3& p_vector); /** expand to contain a point if necesary */

	operator String() const;

	_FORCE_INLINE_ AABB() {}
	inline AABB(const Vector3 &p_pos,const Vector3& p_size) { pos=p_pos; size=p_size; }


};

inline bool AABB::intersects(const AABB& p_aabb) const {

	if ( pos.x >= (p_aabb.pos.x + p_aabb.size.x) )
                return false;
	if ( (pos.x+size.x) <= p_aabb.pos.x  )
                return false;
	if ( pos.y >= (p_aabb.pos.y + p_aabb.size.y) )
                return false;
	if ( (pos.y+size.y) <= p_aabb.pos.y  )
                return false;
	if ( pos.z >= (p_aabb.pos.z + p_aabb.size.z) )
                return false;
	if ( (pos.z+size.z) <= p_aabb.pos.z  )
                return false;

        return true;
}


inline bool AABB::encloses(const AABB & p_aabb) const {

	Vector3 src_min=pos;
	Vector3 src_max=pos+size;
	Vector3 dst_min=p_aabb.pos;
	Vector3 dst_max=p_aabb.pos+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 = pos + 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( pos.x	, pos.y		, pos.z		);
		case 1: return Vector3( pos.x	, pos.y		, pos.z+size.z	);
		case 2: return Vector3( pos.x	, pos.y+size.y	, pos.z		);
		case 3: return Vector3( pos.x	, pos.y+size.y	, pos.z+size.z	);
		case 4: return Vector3( pos.x+size.x	, pos.y		, pos.z		);
		case 5: return Vector3( pos.x+size.x	, pos.y		, pos.z+size.z	);
		case 6: return Vector3( pos.x+size.x	, pos.y+size.y	, pos.z		);
		case 7: return Vector3( pos.x+size.x	, pos.y+size.y	, pos.z+size.z	);
	};

	ERR_FAIL_V(Vector3());
}

bool AABB::intersects_convex_shape(const Plane *p_planes, int p_plane_count) const {

#if 1

	Vector3 half_extents = size * 0.5;
	Vector3 ofs = pos + 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;
#else
	//cache all points to check against!
// #warning should be easy to optimize, just use the same as when taking the support and use only that point
	Vector3 points[8] = {
		Vector3( pos.x	, pos.y		, pos.z		),
		Vector3( pos.x	, pos.y		, pos.z+size.z	),
		Vector3( pos.x	, pos.y+size.y	, pos.z		),
		Vector3( pos.x	, pos.y+size.y	, pos.z+size.z	),
		Vector3( pos.x+size.x	, pos.y		, pos.z		),
		Vector3( pos.x+size.x	, pos.y		, pos.z+size.z	),
		Vector3( pos.x+size.x	, pos.y+size.y	, pos.z		),
		Vector3( pos.x+size.x	, pos.y+size.y	, pos.z+size.z	),
	};

	for (int i=0;i<p_plane_count;i++) { //for each plane

		const Plane & plane=p_planes[i];
		bool all_points_over=true;
		//test if it has all points over!

		for (int j=0;j<8;j++) {


			if (!plane.is_point_over( points[j] )) {

				all_points_over=false;
				break;
			}

		}

		if (all_points_over) {

			return false;
		}
	}
	return true;
#endif
}

bool AABB::has_point(const Vector3& p_point) const {

	if (p_point.x<pos.x)
		return false;
	if (p_point.y<pos.y)
		return false;
	if (p_point.z<pos.z)
		return false;
	if (p_point.x>pos.x+size.x)
		return false;
	if (p_point.y>pos.y+size.y)
		return false;
	if (p_point.z>pos.z+size.z)
		return false;
		
	return true;
}


inline void AABB::expand_to(const Vector3& p_vector) {

	Vector3 begin=pos;
	Vector3 end=pos+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;

	pos=begin;
	size=end-begin;
}

void AABB::project_range_in_plane(const Plane& p_plane,float &r_min,float& r_max) const {

	Vector3 half_extents( size.x * 0.5, size.y * 0.5, size.z * 0.5 );
	Vector3 center( pos.x + half_extents.x, pos.y + half_extents.y, pos.z + half_extents.z );
		
	float length = p_plane.normal.abs().dot(half_extents);
	float 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 &from,const Vector3& dir, float t0, float t1) const {

	float divx=1.0/dir.x;
	float divy=1.0/dir.y;
	float divz=1.0/dir.z;

	Vector3 upbound=pos+size;
	float tmin, tmax, tymin, tymax, tzmin, tzmax;
	if (dir.x >= 0) {
		tmin = (pos.x - from.x) * divx;
		tmax = (upbound.x - from.x) * divx;
	}
	else {
		tmin = (upbound.x - from.x) * divx;
		tmax = (pos.x - from.x) * divx;
	}
	if (dir.y >= 0) {
		tymin = (pos.y - from.y) * divy;
		tymax = (upbound.y - from.y) * divy;
	}
	else {
		tymin = (upbound.y - from.y) * divy;
		tymax = (pos.y - from.y) * divy;
	}
	if ( (tmin > tymax) || (tymin > tmax) )
		return false;
	if (tymin > tmin)
			tmin = tymin;
	if (tymax < tmax)
		tmax = tymax;
	if (dir.z >= 0) {
		tzmin = (pos.z - from.z) * divz;
		tzmax = (upbound.z - from.z) * divz;
	}
	else {
		tzmin = (upbound.z - from.z) * divz;
		tzmax = (pos.z - 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) {

	pos.x-=p_amount;
	pos.y-=p_amount;
	pos.z-=p_amount;
	size.x+=2.0*p_amount;
	size.y+=2.0*p_amount;
	size.z+=2.0*p_amount;
}

typedef AABB Rect3;

#endif // AABB_H