}
+static int ptarray_segmentize_sphere_edge_recursive (
+ const POINT3D *p1, const POINT3D *p2, /* 3-space points we are interpolating beween */
+ const POINT4D *v1, const POINT4D *v2, /* real values and z/m values */
+ double d, double max_seg_length, /* current segment length and segment limit */
+ POINTARRAY *pa) /* write out results here */
+{
+ /* Reached the terminal leaf in recursion. Add */
+ /* the left-most point to the pointarray here */
+ /* We recurse down the left side first, so outputs should */
+ /* end up added to the array in order this way */
+ if (d <= max_seg_length)
+ {
+ GEOGRAPHIC_POINT g;
+ POINT4D p;
+ cart2geog(p1, &g);
+ p.x = rad2deg(g.lon);
+ p.y = rad2deg(g.lat);
+ p.z = v1->z;
+ p.m = v1->m;
+ return ptarray_append_point(pa, &p, LW_FALSE);
+ }
+ /* Find the mid-point and recurse on the left and then the right */
+ else
+ {
+ /* Calculate mid-point */
+ POINT3D mid;
+ mid.x = (p1->x + p2->x) / 2.0;
+ mid.y = (p1->y + p2->y) / 2.0;
+ mid.z = (p1->z + p2->z) / 2.0;
+ normalize(&mid);
+
+ /* Calculate z/m mid-values */
+ /* (ignore x/y, we get those from the 3-space calculations) */
+ POINT4D midv;
+ midv.z = (v1->z + v2->z) / 2.0;
+ midv.m = (v1->m + v2->m) / 2.0;
+ /* Recurse on the left first */
+ ptarray_segmentize_sphere_edge_recursive(p1, &mid, v1, &midv, d/2.0, max_seg_length, pa);
+ ptarray_segmentize_sphere_edge_recursive(&mid, p2, &midv, v2, d/2.0, max_seg_length, pa);
+ return LW_SUCCESS;
+ }
+}
+
+
+/* xxx */
+// void geog2cart(const GEOGRAPHIC_POINT *g, POINT3D *p);
+// #define deg2rad(d) (M_PI * (d) / 180.0)
+// #define rad2deg(r) (180.0 * (r) / M_PI)
+
/**
* Create a new point array with no segment longer than the input segment length (expressed in radians!)
* @param pa_in - input point array pointer
POINTARRAY *pa_out;
int hasz = ptarray_has_z(pa_in);
int hasm = ptarray_has_m(pa_in);
- int pa_in_offset = 0; /* input point offset */
- POINT4D p1, p2, p;
- GEOGRAPHIC_POINT g1, g2, g;
- double d;
+ POINT4D p1, p2;
+ POINT3D q1, q2;
+ GEOGRAPHIC_POINT g1, g2;
+ int i;
/* Just crap out on crazy input */
if ( ! pa_in )
- lwerror("ptarray_segmentize_sphere: null input pointarray");
+ lwerror("%s: null input pointarray", __func__);
if ( max_seg_length <= 0.0 )
- lwerror("ptarray_segmentize_sphere: maximum segment length must be positive");
+ lwerror("%s: maximum segment length must be positive", __func__);
/* Empty starting array */
pa_out = ptarray_construct_empty(hasz, hasm, pa_in->npoints);
- /* Add first point */
- getPoint4d_p(pa_in, pa_in_offset, &p1);
- ptarray_append_point(pa_out, &p1, LW_FALSE);
- geographic_point_init(p1.x, p1.y, &g1);
- pa_in_offset++;
-
- while ( pa_in_offset < pa_in->npoints )
+ /* Simple loop per edge */
+ for (i = 1; i < pa_in->npoints; i++)
{
- getPoint4d_p(pa_in, pa_in_offset, &p2);
+ getPoint4d_p(pa_in, i-1, &p1);
+ getPoint4d_p(pa_in, i, &p2);
+ geographic_point_init(p1.x, p1.y, &g1);
geographic_point_init(p2.x, p2.y, &g2);
/* Skip duplicate points (except in case of 2-point lines!) */
- if ( (pa_in->npoints > 2) && p4d_same(&p1, &p2) )
- {
- /* Move one offset forward */
- p1 = p2;
- g1 = g2;
- pa_in_offset++;
+ if ((pa_in->npoints > 2) && p4d_same(&p1, &p2))
continue;
- }
/* How long is this edge? */
- d = sphere_distance(&g1, &g2);
+ double d = sphere_distance(&g1, &g2);
- /* We need to segmentize this edge */
- if ( d > max_seg_length )
+ if (d > max_seg_length)
{
- int nsegs = 1 + d / max_seg_length;
- int i;
- double dzz = 0, dmm = 0;
- double delta = d / nsegs;
-
- /* The independent Z/M values on the ptarray */
- if ( hasz ) dzz = (p2.z - p1.z) / nsegs;
- if ( hasm ) dmm = (p2.m - p1.m) / nsegs;
-
- g = g1;
- p = p1;
- for ( i = 0; i < nsegs - 1; i++ )
- {
- GEOGRAPHIC_POINT gn;
- double heading;
-
- /* Compute the current heading to the destination */
- heading = sphere_direction(&g, &g2, (nsegs-i) * delta);
- /* Move one increment forwards */
- sphere_project(&g, delta, heading, &gn);
- g = gn;
-
- p.x = rad2deg(g.lon);
- p.y = rad2deg(g.lat);
- if ( hasz )
- p.z += dzz;
- if ( hasm )
- p.m += dmm;
- ptarray_append_point(pa_out, &p, LW_FALSE);
- }
-
- ptarray_append_point(pa_out, &p2, LW_FALSE);
+ geog2cart(&g1, &q1);
+ geog2cart(&g2, &q2);
+ /* 3-d end points, XYZM end point, current edge size, min edge size */
+ ptarray_segmentize_sphere_edge_recursive(&q1, &q2, &p1, &p2, d, max_seg_length, pa_out);
}
- /* This edge is already short enough */
+ /* If we don't segmentize, we need to add first point manually */
else
{
- ptarray_append_point(pa_out, &p2, (pa_in->npoints==2)?LW_TRUE:LW_FALSE);
+ ptarray_append_point(pa_out, &p1, LW_TRUE);
}
-
- /* Move one offset forward */
- p1 = p2;
- g1 = g2;
- pa_in_offset++;
}
-
+ /* Always add the last point */
+ ptarray_append_point(pa_out, &p2, LW_TRUE);
return pa_out;
}
projects / postgis / commitdiff