lw_dist2d_arc_arc_concentric()

int lw_dist2d_arc_arc_concentric	(	const POINT2D *	A1,
		const POINT2D *	A2,
		const POINT2D *	A3,
		double	radius_A,
		const POINT2D *	B1,
		const POINT2D *	B2,
		const POINT2D *	B3,
		double	radius_B,
		const POINT2D *	CENTER,
		DISTPTS *	dl
	)

Definition at line 1675 of file measures.c.

References DISTPTS::distance, distance2d_sqr_pt_pt(), lw_segment_side(), LW_TRUE, DISTPTS::p1, DISTPTS::p2, POINT2D::x, and POINT2D::y.

Referenced by lw_dist2d_arc_arc(), and lw_dist2d_pt_arc().

{
        int seg_size;
        double dist_sqr, shortest_sqr;
        const POINT2D *P1;
        const POINT2D *P2;
        POINT2D proj;

        if (radius_A == radius_B)
        {
                /* Check if B1 or B3 are in the same side as A2 in the A1-A3 arc */
                seg_size = lw_segment_side(A1, A3, A2);
                if (seg_size == lw_segment_side(A1, A3, B1))
                {
                        dl->p1 = *B1;
                        dl->p2 = *B1;
                        dl->distance = 0;
                        return LW_TRUE;
                }
                if (seg_size == lw_segment_side(A1, A3, B3))
                {
                        dl->p1 = *B3;
                        dl->p2 = *B3;
                        dl->distance = 0;
                        return LW_TRUE;
                }
                /* Check if A1 or A3 are in the same side as B2 in the B1-B3 arc */
                seg_size = lw_segment_side(B1, B3, B2);
                if (seg_size == lw_segment_side(B1, B3, A1))
                {
                        dl->p1 = *A1;
                        dl->p2 = *A1;
                        dl->distance = 0;
                        return LW_TRUE;
                }
                if (seg_size == lw_segment_side(B1, B3, A3))
                {
                        dl->p1 = *A3;
                        dl->p2 = *A3;
                        dl->distance = 0;
                        return LW_TRUE;
                }
        }
        else
        {
                /* Check if any projection of B ends are in A*/
                seg_size = lw_segment_side(A1, A3, A2);

                /* B1 */
                proj.x = CENTER->x + (B1->x - CENTER->x) * radius_A / radius_B;
                proj.y = CENTER->y + (B1->y - CENTER->y) * radius_A / radius_B;

                if (seg_size == lw_segment_side(A1, A3, &proj))
                {
                        dl->p1 = proj;
                        dl->p2 = *B1;
                        dl->distance = fabs(radius_A - radius_B);
                        return LW_TRUE;
                }
                /* B3 */
                proj.x = CENTER->x + (B3->x - CENTER->x) * radius_A / radius_B;
                proj.y = CENTER->y + (B3->y - CENTER->y) * radius_A / radius_B;
                if (seg_size == lw_segment_side(A1, A3, &proj))
                {
                        dl->p1 = proj;
                        dl->p2 = *B3;
                        dl->distance = fabs(radius_A - radius_B);
                        return LW_TRUE;
                }

                /* Now check projections of A in B */
                seg_size = lw_segment_side(B1, B3, B2);

                /* A1 */
                proj.x = CENTER->x + (A1->x - CENTER->x) * radius_B / radius_A;
                proj.y = CENTER->y + (A1->y - CENTER->y) * radius_B / radius_A;
                if (seg_size == lw_segment_side(B1, B3, &proj))
                {
                        dl->p1 = proj;
                        dl->p2 = *A1;
                        dl->distance = fabs(radius_A - radius_B);
                        return LW_TRUE;
                }

                /* A3 */
                proj.x = CENTER->x + (A3->x - CENTER->x) * radius_B / radius_A;
                proj.y = CENTER->y + (A3->y - CENTER->y) * radius_B / radius_A;
                if (seg_size == lw_segment_side(B1, B3, &proj))
                {
                        dl->p1 = proj;
                        dl->p2 = *A3;
                        dl->distance = fabs(radius_A - radius_B);
                        return LW_TRUE;
                }
        }

        /* Check the shortest between the distances of the 4 ends */
        shortest_sqr = dist_sqr = distance2d_sqr_pt_pt(A1, B1);
        P1 = A1;
        P2 = B1;

        dist_sqr = distance2d_sqr_pt_pt(A1, B3);
        if (dist_sqr < shortest_sqr)
        {
                shortest_sqr = dist_sqr;
                P1 = A1;
                P2 = B3;
        }

        dist_sqr = distance2d_sqr_pt_pt(A3, B1);
        if (dist_sqr < shortest_sqr)
        {
                shortest_sqr = dist_sqr;
                P1 = A3;
                P2 = B1;
        }

        dist_sqr = distance2d_sqr_pt_pt(A3, B3);
        if (dist_sqr < shortest_sqr)
        {
                shortest_sqr = dist_sqr;
                P1 = A3;
                P2 = B3;
        }

        dl->p1 = *P1;
        dl->p2 = *P2;
        dl->distance = sqrt(shortest_sqr);

        return LW_TRUE;
}

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