virtualx-engine/core/math/face3.h

/*************************************************************************/
/*  face3.h                                                              */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
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/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                 */
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/*************************************************************************/
#ifndef FACE3_H
#define FACE3_H

#include "vector3.h"
#include "plane.h"
#include "aabb.h"
#include "transform.h"

class Face3 {
public:

        enum Side {
                SIDE_OVER,
                SIDE_UNDER,
                SIDE_SPANNING,
                SIDE_COPLANAR
        };


        Vector3 vertex[3];

        /**
         *
         * @param p_plane plane used to split the face
         * @param p_res array of at least 3 faces, amount used in functio return
         * @param p_is_point_over array of at least 3 booleans, determining which face is over the plane, amount used in functio return
         * @param _epsilon constant used for numerical error rounding, to add "thickness" to the plane (so coplanar points can happen)
         * @return amount of faces generated by the split, either 0 (means no split possible), 2 or 3
         */
                  
        int split_by_plane(const Plane& p_plane,Face3 *p_res,bool *p_is_point_over) const;

	Plane get_plane(ClockDirection p_dir=CLOCKWISE) const;
	Vector3 get_random_point_inside() const;


        Side get_side_of(const Face3& p_face,ClockDirection p_clock_dir=CLOCKWISE) const;

        bool is_degenerate() const;
	real_t get_area() const;

        Vector3 get_median_point() const;

	bool intersects_ray(const Vector3& p_from,const Vector3& p_dir,Vector3 * p_intersection=0) const;
	bool intersects_segment(const Vector3& p_from,const Vector3& p_dir,Vector3 * p_intersection=0) const;

        ClockDirection get_clock_dir() const; ///< todo, test if this is returning the proper clockwisity

        void get_support(const Vector3& p_normal,const Transform& p_transform,Vector3 *p_vertices,int* p_count,int p_max) const;
        void project_range(const Vector3& p_normal,const Transform& p_transform,float& r_min, float& r_max) const;
        
        AABB get_aabb() const {

                AABB aabb( vertex[0], Vector3() );
                aabb.expand_to( vertex[1] );
                aabb.expand_to( vertex[2] );
                return aabb;
        }

        bool intersects_aabb(const AABB& p_aabb) const;
	_FORCE_INLINE_ bool intersects_aabb2(const AABB& p_aabb) const;
	operator String() const;

        inline Face3() {}
        inline Face3(const Vector3 &p_v1,const Vector3 &p_v2,const Vector3 &p_v3) { vertex[0]=p_v1; vertex[1]=p_v2; vertex[2]=p_v3; }

};


bool Face3::intersects_aabb2(const AABB& p_aabb) const {

	Vector3 perp = (vertex[0]-vertex[2]).cross(vertex[0]-vertex[1]);

	Vector3 half_extents = p_aabb.size * 0.5;
	Vector3 ofs = p_aabb.pos + half_extents;

	Vector3 sup =Vector3(
			(perp.x>0) ? -half_extents.x : half_extents.x,
			(perp.y>0) ? -half_extents.y : half_extents.y,
			(perp.z>0) ? -half_extents.z : half_extents.z
		);

	float d = perp.dot(vertex[0]);
	float dist_a = perp.dot(ofs+sup)-d;
	float dist_b = perp.dot(ofs-sup)-d;

	if (dist_a*dist_b > 0)
		return false; //does not intersect the plane


#define TEST_AXIS(m_ax)\
	{\
		float aabb_min=p_aabb.pos.m_ax;\
		float aabb_max=p_aabb.pos.m_ax+p_aabb.size.m_ax;\
		float tri_min,tri_max;\
		for (int i=0;i<3;i++) {\
			if (i==0 || vertex[i].m_ax > tri_max)\
				tri_max=vertex[i].m_ax;\
			if (i==0 || vertex[i].m_ax < tri_min)\
				tri_min=vertex[i].m_ax;\
		}\
\
		if (tri_max<aabb_min || aabb_max<tri_min)\
			return false;\
	}

	TEST_AXIS(x);
	TEST_AXIS(y);
	TEST_AXIS(z);

#undef TEST_AXIS


	Vector3 edge_norms[3]={
		vertex[0]-vertex[1],
		vertex[1]-vertex[2],
		vertex[2]-vertex[0],
	};

	for (int i=0;i<12;i++) {

		Vector3 from,to;
		switch(i) {

			case 0:{

				from=Vector3( p_aabb.pos.x+p_aabb.size.x	, p_aabb.pos.y		, p_aabb.pos.z		);
				to=Vector3( p_aabb.pos.x	, p_aabb.pos.y		, p_aabb.pos.z		);
			} break;
			case 1:{

				from=Vector3( p_aabb.pos.x+p_aabb.size.x	, p_aabb.pos.y		, p_aabb.pos.z+p_aabb.size.z	);
				to=Vector3( p_aabb.pos.x+p_aabb.size.x	, p_aabb.pos.y		, p_aabb.pos.z		);
			} break;
			case 2:{
				from=Vector3( p_aabb.pos.x	, p_aabb.pos.y		, p_aabb.pos.z+p_aabb.size.z	);
				to=Vector3( p_aabb.pos.x+p_aabb.size.x	, p_aabb.pos.y		, p_aabb.pos.z+p_aabb.size.z	);

			} break;
			case 3:{

				from=Vector3( p_aabb.pos.x	, p_aabb.pos.y		, p_aabb.pos.z		);
				to=Vector3( p_aabb.pos.x	, p_aabb.pos.y		, p_aabb.pos.z+p_aabb.size.z	);

			} break;
			case 4:{

				from=Vector3( p_aabb.pos.x	, p_aabb.pos.y+p_aabb.size.y		, p_aabb.pos.z		);
				to=Vector3( p_aabb.pos.x+p_aabb.size.x	, p_aabb.pos.y+p_aabb.size.y		, p_aabb.pos.z		);
			} break;
			case 5:{

				from=Vector3( p_aabb.pos.x+p_aabb.size.x	, p_aabb.pos.y+p_aabb.size.y		, p_aabb.pos.z		);
				to=Vector3( p_aabb.pos.x+p_aabb.size.x	, p_aabb.pos.y+p_aabb.size.y		, p_aabb.pos.z+p_aabb.size.z	);
			} break;
			case 6:{
				from=Vector3( p_aabb.pos.x+p_aabb.size.x	, p_aabb.pos.y+p_aabb.size.y		, p_aabb.pos.z+p_aabb.size.z	);
				to=Vector3( p_aabb.pos.x	, p_aabb.pos.y+p_aabb.size.y		, p_aabb.pos.z+p_aabb.size.z	);

			} break;
			case 7:{

				from=Vector3( p_aabb.pos.x	, p_aabb.pos.y+p_aabb.size.y		, p_aabb.pos.z+p_aabb.size.z	);
				to=Vector3( p_aabb.pos.x	, p_aabb.pos.y+p_aabb.size.y		, p_aabb.pos.z		);

			} break;
			case 8:{

				from=Vector3( p_aabb.pos.x	, p_aabb.pos.y		, p_aabb.pos.z+p_aabb.size.z	);
				to=Vector3( p_aabb.pos.x	, p_aabb.pos.y+p_aabb.size.y		, p_aabb.pos.z+p_aabb.size.z	);

			} break;
			case 9:{

				from=Vector3( p_aabb.pos.x	, p_aabb.pos.y		, p_aabb.pos.z		);
				to=Vector3( p_aabb.pos.x	, p_aabb.pos.y+p_aabb.size.y	, p_aabb.pos.z		);

			} break;
			case 10:{

				from=Vector3( p_aabb.pos.x+p_aabb.size.x	, p_aabb.pos.y		, p_aabb.pos.z		);
				to=Vector3( p_aabb.pos.x+p_aabb.size.x	, p_aabb.pos.y+p_aabb.size.y	, p_aabb.pos.z		);

			} break;
			case 11:{

				from=Vector3( p_aabb.pos.x+p_aabb.size.x	, p_aabb.pos.y		, p_aabb.pos.z+p_aabb.size.z		);
				to=Vector3( p_aabb.pos.x+p_aabb.size.x	, p_aabb.pos.y+p_aabb.size.y	, p_aabb.pos.z+p_aabb.size.z		);

			} break;

		}

		Vector3 e1=from-to;
		for (int j=0;j<3;j++) {
			Vector3 e2=edge_norms[j];

			Vector3 axis=vec3_cross( e1, e2 );

			if (axis.length_squared()<0.0001)
				continue; // coplanar
			//axis.normalize();

			Vector3 sup2 =Vector3(
					(axis.x>0) ? -half_extents.x : half_extents.x,
					(axis.y>0) ? -half_extents.y : half_extents.y,
					(axis.z>0) ? -half_extents.z : half_extents.z
				);

			float maxB = axis.dot(ofs+sup2);
			float minB = axis.dot(ofs-sup2);
			if (minB>maxB) {
				SWAP(maxB,minB);
			}

			float minT=1e20,maxT=-1e20;
			for (int k=0;k<3;k++) {

				float d=axis.dot(vertex[k]);

				if (d > maxT)
					maxT=d;

				if (d < minT)
					minT=d;
			}

			if (maxB<minT || maxT<minB)
				return false;
		}
	}
	return true;


}


#endif // FACE3_H