distance2d_sqr_pt_seg()

double distance2d_sqr_pt_seg	(	const POINT2D *	p,
		const POINT2D *	A,
		const POINT2D *	B
	)

Definition at line 2391 of file measures.c.

References distance2d_sqr_pt_pt(), r, s, POINT2D::x, and POINT2D::y.

Referenced by ptarray_dp_findsplit().

{
        double  r,s;

        if (  ( A->x == B->x) && (A->y == B->y) )
                return distance2d_sqr_pt_pt(p,A);

        r = ( (p->x-A->x) * (B->x-A->x) + (p->y-A->y) * (B->y-A->y) )/( (B->x-A->x)*(B->x-A->x) +(B->y-A->y)*(B->y-A->y) );

        if (r<0) return distance2d_sqr_pt_pt(p,A);
        if (r>1) return distance2d_sqr_pt_pt(p,B);


        /*
         * (2)
         *           (Ay-Cy)(Bx-Ax)-(Ax-Cx)(By-Ay)
         *      s = -----------------------------
         *                      L^2
         *
         *      Then the distance from C to P = |s|*L.
         *
         */

        s = ( (A->y-p->y)*(B->x-A->x)- (A->x-p->x)*(B->y-A->y) ) /
            ( (B->x-A->x)*(B->x-A->x) +(B->y-A->y)*(B->y-A->y) );

        return s * s * ( (B->x-A->x)*(B->x-A->x) + (B->y-A->y)*(B->y-A->y) );
}

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