curve_helper.h

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/* === S Y N F I G ========================================================= */
/* ========================================================================= */

/* === S T A R T =========================================================== */

#ifndef __SYNFIG_CURVE_HELPER_H
#define __SYNFIG_CURVE_HELPER_H

/* === H E A D E R S ======================================================= */
#include <ETL/bezier>

#include "rect.h"
#include "real.h"
#include "vector.h"

#include <vector>

/* === M A C R O S ========================================================= */

/* === T Y P E D E F S ===================================================== */

/* === C L A S S E S & S T R U C T S ======================================= */

namespace synfig {

//line helper functions
inline Real line_point_distsq(const Point &p1, const Point &p2,
                                        const Point &p, float &t)
{
    Vector v,vt;

    v = p2 - p1;
    vt = p - p1;

    t = v.mag_squared() > 1e-12 ? (vt*v)/v.mag_squared() : 0; //get the projected time value for the current line

    //get distance to line segment with the time value clamped 0-1
    if(t >= 1)  //use p+v
    {
        vt += v; //makes it pp - (p+v)
        t = 1;
    }else if(t > 0) //use vt-proj
    {
        vt -= v * t; // vt - proj_v(vt) //must normalize the projection vector to work
    }else
    {
        t = 0;
    }

    //else use p
    return vt.mag_squared();
}


//----- RAY CLASS AND FUNCTIONS --------------
struct Ray
{
    Point   p;
    Vector  v;

    Ray() {}
    Ray(const Point &pin, const Vector &vin):p(pin), v(vin) {}
};

/* This algorithm calculates the INTERSECTION of 2 line segments
    (not the closest point or anything like that, just intersection)
    //parameter values returned are [0,1]
*/
int intersect(const Point &p1, const Vector &v1, float &t1,
                const Point &p2, const Vector &v2, float &t2);

inline bool intersect_line_segments(const Point &a, const Point &b, float &tout,
                                        const Point &c, const Point &d, float &sout)
{
    Vector v1(b-a), v2(d-c);

    //ok so treat both lines as parametric (so we can find the time values simultaneously)
    float t,s;

    if( intersect(a,v1,t, b,v2,s) && t >= 0 && t <= 1 && s >= 0 && s <= 1 )
    {
        tout = t;
        sout = s;
        return true;
    }

    return false;
}

//Find the closest point on the curve to a point (and return its distance, and time value)
Real find_closest(const etl::bezier<Point> &curve, const Point &point, float step, Real *closest, float *t);

//----------- Rectangle helper functions ---------------

template < typename T >
inline void Bound(etl::rect<T> &r, const etl::bezier<Point> &b)
{
    r.set_point(b[0][0],b[0][1]);
    r.expand(b[1][0],b[1][1]);
    r.expand(b[2][0],b[2][1]);
    r.expand(b[3][0],b[3][1]);
}

/*template < typename T >
inline bool intersect(const etl::rect<T> &r1, const etl::rect<T> &r2)
{
    return (r1.minx < r2.maxx) &
            (r2.minx < r1.maxx) &
            (r1.miny < r2.maxy) &
            (r2.miny < r1.maxy);
}*/

//----- Convex Hull of a Bezier Curve --------------
struct BezHull
{
    Point   p[4];
    int     size;

    void Bound(const etl::bezier<Point> &b);
};

//Line Intersection
int intersect(const Rect &r1, const Point &p, const Vector &v);
int intersect(const Rect &r1, const Point &p); //inside or to the right
int intersect(const BezHull &bh, const Point &p, const Vector &v);
//int intersect(const etl::bezier<Point> &b, const Point &p, const Vector &v);
int intersect(const etl::bezier<Point> &b, const Point &p); //for use in containment tests for regions

//Curve intersection object
class CIntersect
{
public:
    struct SCurve;
private:
    void recurse_intersect(const SCurve &left, const SCurve &right, int depth = 0);

public:
    //size should be equal
    typedef std::vector< std::pair<float,float > >  intersect_set;
    intersect_set   times;

    int     max_depth;

    CIntersect();

    bool operator()(const etl::bezier<Point> &b1, const etl::bezier<Point> &b2);
};

}; // END of namespace studio

/* === E N D =============================================================== */

#endif