lw_dist3d_ptarray_poly()

int lw_dist3d_ptarray_poly	(	POINTARRAY *	pa,
		LWPOLY *	poly,
		PLANE3D *	plane,
		DISTPTS3D *	dl
	)

Computes pointarray to polygon distance.

Definition at line 1077 of file measures3d.c.

References DISTPTS3D::distance, get_3dvector_from_points(), getPoint3dz_p(), intersects(), lw_dist3d_pt_poly(), lw_dist3d_ptarray_ptarray(), LW_FALSE, LW_TRUE, POINTARRAY::npoints, LWPOLY::nrings, rect_node::p1, DISTPTS3D::p1, rect_node::p2, DISTPTS3D::p2, project_point_on_plane(), pt_in_ring_3d(), LWPOLY::rings, DISTPTS3D::tolerance, VECTOR3D::x, POINT3DZ::x, VECTOR3D::y, POINT3DZ::y, VECTOR3D::z, and POINT3DZ::z.

Referenced by lw_dist3d_line_poly(), and lw_dist3d_poly_poly().

{


        int i,j,k;
        double f, s1, s2;
        VECTOR3D projp1_projp2;
        POINT3DZ p1, p2,projp1, projp2, intersectionp;

        getPoint3dz_p(pa, 0, &p1);

        s1 = project_point_on_plane(
            &p1, plane, &projp1); /*the sign of s1 tells us on which side of the plane the point is. */
        lw_dist3d_pt_poly(&p1, poly, plane,&projp1, dl);
        if ((s1 == 0.0) && (dl->distance < dl->tolerance))
        {
                return LW_TRUE;
        }

        for (i=1;i<pa->npoints;i++)
        {
                int intersects;
                getPoint3dz_p(pa, i, &p2);
                s2=project_point_on_plane(&p2, plane, &projp2);
                lw_dist3d_pt_poly(&p2, poly, plane,&projp2, dl);
                if ((s2 == 0.0) && (dl->distance < dl->tolerance))
                {
                        return LW_TRUE;
                }

                /*If s1and s2 has different signs that means they are on different sides of the plane of the polygon.
                That means that the edge between the points crosses the plane and might intersect with the polygon*/
                if ((s1 * s2) < 0)
                {
                        f=fabs(s1)/(fabs(s1)+fabs(s2)); /*The size of s1 and s2 is the distance from the point to the plane.*/
                        get_3dvector_from_points(&projp1, &projp2,&projp1_projp2);

                        /*get the point where the line segment crosses the plane*/
                        intersectionp.x=projp1.x+f*projp1_projp2.x;
                        intersectionp.y=projp1.y+f*projp1_projp2.y;
                        intersectionp.z=projp1.z+f*projp1_projp2.z;

                        intersects = LW_TRUE; /*We set intersects to true until the opposite is proved*/

                        if(pt_in_ring_3d(&intersectionp, poly->rings[0], plane)) /*Inside outer ring*/
                        {
                                for (k=1;k<poly->nrings; k++)
                                {
                                        /* Inside a hole, so no intersection with the polygon*/
                                        if ( pt_in_ring_3d(&intersectionp, poly->rings[k], plane ))
                                        {
                                                intersects=LW_FALSE;
                                                break;
                                        }
                                }
                                if(intersects)
                                {
                                        dl->distance=0.0;
                                        dl->p1.x=intersectionp.x;
                                        dl->p1.y=intersectionp.y;
                                        dl->p1.z=intersectionp.z;

                                        dl->p2.x=intersectionp.x;
                                        dl->p2.y=intersectionp.y;
                                        dl->p2.z=intersectionp.z;
                                        return LW_TRUE;

                                }
                        }
                }

                projp1=projp2;
                s1=s2;
                p1=p2;
        }

        /*check or pointarray against boundary and inner boundaries of the polygon*/
        for (j=0;j<poly->nrings;j++)
        {
                lw_dist3d_ptarray_ptarray(pa, poly->rings[j], dl);
        }

return LW_TRUE;
}

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