face3.h

/*************************************************************************/
/*  face3.h                                                              */
/*************************************************************************/
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/*                           GODOT ENGINE                                */
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/* Copyright (c) 2007-2016 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];

        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;
    Vector3 get_closest_point_to(const Vector3& p_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; 

        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