static POINTARRAY*
ptarray_locate_along(const POINTARRAY *pa, double m, double offset)
{
int i;
POINT4D p1, p2, pn;
POINTARRAY *dpa = NULL;
/* Can't do anything with degenerate point arrays */
if ( ! pa || pa->npoints < 2 ) return NULL;
/* Walk through each segment in the point array */
for ( i = 1; i < pa->npoints; i++ )
{
getPoint4d_p(pa, i-1, &p1);
getPoint4d_p(pa, i, &p2);
/* No derived point? Move to next segment. */
if ( segment_locate_along(&p1, &p2, m, offset, &pn) == LW_FALSE )
continue;
/* No pointarray, make a fresh one */
if ( dpa == NULL )
dpa = ptarray_construct_empty(ptarray_has_z(pa), ptarray_has_m(pa), 8);
/* Add our new point to the array */
ptarray_append_point(dpa, &pn, 0);
}
return dpa;
}
static LWGEOM*
linestring_from_pa(const POINTARRAY *pa, int srid, int start, int end)
{
int i = 0, j = 0;
POINT4D p;
POINTARRAY *pao = ptarray_construct(ptarray_has_z(pa), ptarray_has_m(pa), end-start+2);
LWDEBUGF(4, "srid=%d, start=%d, end=%d", srid, start, end);
for( i = start; i < end + 2; i++ )
{
getPoint4d_p(pa, i, &p);
ptarray_set_point4d(pao, j++, &p);
}
return lwline_as_lwgeom(lwline_construct(srid, NULL, pao));
}
static LWGEOM*
circstring_from_pa(const POINTARRAY *pa, int srid, int start, int end)
{
POINT4D p0, p1, p2;
POINTARRAY *pao = ptarray_construct(ptarray_has_z(pa), ptarray_has_m(pa), 3);
LWDEBUGF(4, "srid=%d, start=%d, end=%d", srid, start, end);
getPoint4d_p(pa, start, &p0);
ptarray_set_point4d(pao, 0, &p0);
getPoint4d_p(pa, (start+end)/2, &p1);
ptarray_set_point4d(pao, 1, &p1);
getPoint4d_p(pa, end+1, &p2);
ptarray_set_point4d(pao, 2, &p2);
return lwcircstring_as_lwgeom(lwcircstring_construct(srid, NULL, pao));
}
LWMPOINT *
lwmpoint_construct(int srid, const POINTARRAY *pa)
{
int i;
int hasz = ptarray_has_z(pa);
int hasm = ptarray_has_m(pa);
LWMPOINT *ret = (LWMPOINT*)lwcollection_construct_empty(MULTIPOINTTYPE, srid, hasz, hasm);
for ( i = 0; i < pa->npoints; i++ )
{
LWPOINT *lwp;
POINT4D p;
getPoint4d_p(pa, i, &p);
lwp = lwpoint_make(srid, hasz, hasm, &p);
lwmpoint_add_lwpoint(ret, lwp);
}
return ret;
}
LWGEOM*
pta_desegmentize(POINTARRAY *points, int type, int srid)
{
int i = 0, j, k;
POINT4D a1, a2, a3, b;
char *edges_in_arcs;
int found_arc = LW_FALSE;
int current_arc = 1;
int num_edges;
int edge_type = -1;
int start, end;
LWCOLLECTION *outcol;
/* Die on null input */
if ( ! points )
lwerror("pta_desegmentize called with null pointarray");
/* Null on empty input? */
if ( points->npoints == 0 )
return NULL;
/* We can't desegmentize anything shorter than four points */
if ( points->npoints < 4 )
{
/* Return a linestring here*/
lwerror("pta_desegmentize needs implementation for npoints < 4");
}
/* Allocate our result array of vertices that are part of arcs */
num_edges = points->npoints - 1;
edges_in_arcs = lwalloc(num_edges);
memset(edges_in_arcs, 0, num_edges);
/* We make a candidate arc of the first two edges, */
/* And then see if the next edge follows it */
while( i < num_edges-2 )
{
found_arc = LW_FALSE;
/* Make candidate arc */
getPoint4d_p(points, i , &a1);
getPoint4d_p(points, i+1, &a2);
getPoint4d_p(points, i+2, &a3);
for( j = i+3; j < num_edges+1; j++ )
{
LWDEBUGF(4, "i=%d, j=%d", i, j);
getPoint4d_p(points, j, &b);
/* Does this point fall on our candidate arc? */
if ( pt_continues_arc(&a1, &a2, &a3, &b) )
{
/* Yes. Mark this edge and the two preceding it as arc components */
LWDEBUGF(4, "pt_continues_arc #%d", current_arc);
found_arc = LW_TRUE;
for ( k = j-1; k > j-4; k-- )
edges_in_arcs[k] = current_arc;
}
else
{
/* No. So we're done with this candidate arc */
LWDEBUG(4, "pt_continues_arc = false");
current_arc++;
break;
}
}
/* Jump past all the edges that were added to the arc */
if ( found_arc )
{
i = j-1;
}
else
{
/* Mark this edge as a linear edge */
edges_in_arcs[i] = 0;
i = i+1;
}
}
#if POSTGIS_DEBUG_LEVEL > 3
{
char *edgestr = lwalloc(num_edges+1);
for ( i = 0; i < num_edges; i++ )
{
if ( edges_in_arcs[i] )
edgestr[i] = 48 + edges_in_arcs[i];
else
edgestr[i] = '.';
}
edgestr[num_edges] = 0;
LWDEBUGF(3, "edge pattern %s", edgestr);
lwfree(edgestr);
}
#endif
start = 0;
edge_type = edges_in_arcs[0];
outcol = lwcollection_construct_empty(COMPOUNDTYPE, srid, ptarray_has_z(points), ptarray_has_m(points));
for( i = 1; i < num_edges; i++ )
{
if( edge_type != edges_in_arcs[i] )
{
end = i - 1;
lwcollection_add_lwgeom(outcol, geom_from_pa(points, srid, edge_type, start, end));
start = i;
edge_type = edges_in_arcs[i];
}
}
/* Roll out last item */
end = num_edges - 1;
lwcollection_add_lwgeom(outcol, geom_from_pa(points, srid, edge_type, start, end));
/* Strip down to singleton if only one entry */
if ( outcol->ngeoms == 1 )
{
LWGEOM *outgeom = outcol->geoms[0];
lwfree(outcol);
return outgeom;
}
return lwcollection_as_lwgeom(outcol);
}
LWGEOM*
pta_unstroke(const POINTARRAY *points, int type, int srid)
{
int i = 0, j, k;
POINT4D a1, a2, a3, b;
POINT4D first, center;
char *edges_in_arcs;
int found_arc = LW_FALSE;
int current_arc = 1;
int num_edges;
int edge_type; /* non-zero if edge is part of an arc */
int start, end;
LWCOLLECTION *outcol;
/* Minimum number of edges, per quadrant, required to define an arc */
const unsigned int min_quad_edges = 2;
/* Die on null input */
if ( ! points )
lwerror("pta_unstroke called with null pointarray");
/* Null on empty input? */
if ( points->npoints == 0 )
return NULL;
/* We can't desegmentize anything shorter than four points */
if ( points->npoints < 4 )
{
/* Return a linestring here*/
lwerror("pta_unstroke needs implementation for npoints < 4");
}
/* Allocate our result array of vertices that are part of arcs */
num_edges = points->npoints - 1;
edges_in_arcs = lwalloc(num_edges + 1);
memset(edges_in_arcs, 0, num_edges + 1);
/* We make a candidate arc of the first two edges, */
/* And then see if the next edge follows it */
while( i < num_edges-2 )
{
unsigned int arc_edges;
double num_quadrants;
double angle;
found_arc = LW_FALSE;
/* Make candidate arc */
getPoint4d_p(points, i , &a1);
getPoint4d_p(points, i+1, &a2);
getPoint4d_p(points, i+2, &a3);
memcpy(&first, &a1, sizeof(POINT4D));
for( j = i+3; j < num_edges+1; j++ )
{
LWDEBUGF(4, "i=%d, j=%d", i, j);
getPoint4d_p(points, j, &b);
/* Does this point fall on our candidate arc? */
if ( pt_continues_arc(&a1, &a2, &a3, &b) )
{
/* Yes. Mark this edge and the two preceding it as arc components */
LWDEBUGF(4, "pt_continues_arc #%d", current_arc);
found_arc = LW_TRUE;
for ( k = j-1; k > j-4; k-- )
edges_in_arcs[k] = current_arc;
}
else
{
/* No. So we're done with this candidate arc */
LWDEBUG(4, "pt_continues_arc = false");
current_arc++;
break;
}
memcpy(&a1, &a2, sizeof(POINT4D));
memcpy(&a2, &a3, sizeof(POINT4D));
memcpy(&a3, &b, sizeof(POINT4D));
}
/* Jump past all the edges that were added to the arc */
if ( found_arc )
{
/* Check if an arc was composed by enough edges to be
* really considered an arc
* See http://trac.osgeo.org/postgis/ticket/2420
*/
arc_edges = j - 1 - i;
LWDEBUGF(4, "arc defined by %d edges found", arc_edges);
if ( first.x == b.x && first.y == b.y ) {
LWDEBUG(4, "arc is a circle");
num_quadrants = 4;
}
else {
lw_arc_center((POINT2D*)&first, (POINT2D*)&b, (POINT2D*)&a1, (POINT2D*)¢er);
angle = lw_arc_angle((POINT2D*)&first, (POINT2D*)¢er, (POINT2D*)&b);
int p2_side = lw_segment_side((POINT2D*)&first, (POINT2D*)&a1, (POINT2D*)&b);
if ( p2_side >= 0 ) angle = -angle;
if ( angle < 0 ) angle = 2 * M_PI + angle;
num_quadrants = ( 4 * angle ) / ( 2 * M_PI );
LWDEBUGF(4, "arc angle (%g %g, %g %g, %g %g) is %g (side is %d), quandrants:%g", first.x, first.y, center.x, center.y, b.x, b.y, angle, p2_side, num_quadrants);
}
/* a1 is first point, b is last point */
if ( arc_edges < min_quad_edges * num_quadrants ) {
LWDEBUGF(4, "Not enough edges for a %g quadrants arc, %g needed", num_quadrants, min_quad_edges * num_quadrants);
for ( k = j-1; k >= i; k-- )
edges_in_arcs[k] = 0;
}
i = j-1;
}
else
{
/* Mark this edge as a linear edge */
edges_in_arcs[i] = 0;
i = i+1;
}
}
#if POSTGIS_DEBUG_LEVEL > 3
{
char *edgestr = lwalloc(num_edges+1);
for ( i = 0; i < num_edges; i++ )
{
if ( edges_in_arcs[i] )
edgestr[i] = 48 + edges_in_arcs[i];
else
edgestr[i] = '.';
}
edgestr[num_edges] = 0;
LWDEBUGF(3, "edge pattern %s", edgestr);
lwfree(edgestr);
}
#endif
start = 0;
edge_type = edges_in_arcs[0];
outcol = lwcollection_construct_empty(COMPOUNDTYPE, srid, ptarray_has_z(points), ptarray_has_m(points));
for( i = 1; i < num_edges; i++ )
{
if( edge_type != edges_in_arcs[i] )
{
end = i - 1;
lwcollection_add_lwgeom(outcol, geom_from_pa(points, srid, edge_type, start, end));
start = i;
edge_type = edges_in_arcs[i];
}
}
lwfree(edges_in_arcs); /* not needed anymore */
/* Roll out last item */
end = num_edges - 1;
lwcollection_add_lwgeom(outcol, geom_from_pa(points, srid, edge_type, start, end));
/* Strip down to singleton if only one entry */
if ( outcol->ngeoms == 1 )
{
LWGEOM *outgeom = outcol->geoms[0];
outcol->ngeoms = 0; lwcollection_free(outcol);
return outgeom;
}
return lwcollection_as_lwgeom(outcol);
}
/**
* Segmentize an arc
*
* Does not add the final vertex
*
* @param to POINTARRAY to append segmentized vertices to
* @param p1 first point defining the arc
* @param p2 second point defining the arc
* @param p3 third point defining the arc
* @param tol tolerance, semantic driven by tolerance_type
* @param tolerance_type see LW_LINEARIZE_TOLERANCE_TYPE
* @param flags LW_LINEARIZE_FLAGS
*
* @return number of points appended (0 if collinear),
* or -1 on error (lwerror would be called).
*
*/
static int
lwarc_linearize(POINTARRAY *to,
const POINT4D *p1, const POINT4D *p2, const POINT4D *p3,
double tol, LW_LINEARIZE_TOLERANCE_TYPE tolerance_type,
int flags)
{
POINT2D center;
POINT2D *t1 = (POINT2D*)p1;
POINT2D *t2 = (POINT2D*)p2;
POINT2D *t3 = (POINT2D*)p3;
POINT4D pt;
int p2_side = 0;
int clockwise = LW_TRUE;
double radius; /* Arc radius */
double increment; /* Angle per segment */
double angle_shift = 0;
double a1, a2, a3, angle;
POINTARRAY *pa = to;
int is_circle = LW_FALSE;
int points_added = 0;
int reverse = 0;
LWDEBUG(2, "lwarc_linearize called.");
p2_side = lw_segment_side(t1, t3, t2);
/* Force counterclockwise scan if SYMMETRIC operation is requsested */
if ( p2_side == -1 && flags & LW_LINEARIZE_FLAG_SYMMETRIC )
{
/* swap p1-p3 */
t1 = (POINT2D*)p3;
t3 = (POINT2D*)p1;
p1 = (POINT4D*)t1;
p3 = (POINT4D*)t3;
p2_side = 1;
reverse = 1;
}
radius = lw_arc_center(t1, t2, t3, ¢er);
LWDEBUGF(2, " center is POINT(%.15g %.15g) - radius:%g", center.x, center.y, radius);
/* Matched start/end points imply circle */
if ( p1->x == p3->x && p1->y == p3->y )
is_circle = LW_TRUE;
/* Negative radius signals straight line, p1/p2/p3 are colinear */
if ( (radius < 0.0 || p2_side == 0) && ! is_circle )
return 0;
/* The side of the p1/p3 line that p2 falls on dictates the sweep
direction from p1 to p3. */
if ( p2_side == -1 )
clockwise = LW_TRUE;
else
clockwise = LW_FALSE;
if ( tolerance_type == LW_LINEARIZE_TOLERANCE_TYPE_SEGS_PER_QUAD )
{{
int perQuad = rint(tol);
// error out if tol != perQuad ? (not-round)
if ( perQuad != tol )
{
lwerror("lwarc_linearize: segments per quadrant must be an integer value, got %.15g", tol, perQuad);
return -1;
}
if ( perQuad < 1 )
{
lwerror("lwarc_linearize: segments per quadrant must be at least 1, got %d", perQuad);
return -1;
}
increment = fabs(M_PI_2 / perQuad);
LWDEBUGF(2, "lwarc_linearize: perQuad:%d, increment:%g (%g degrees)", perQuad, increment, increment*180/M_PI);
}}
else if ( tolerance_type == LW_LINEARIZE_TOLERANCE_TYPE_MAX_DEVIATION )
{{
double halfAngle;
if ( tol <= 0 )
{
lwerror("lwarc_linearize: max deviation must be bigger than 0, got %.15g", tol);
return -1;
}
halfAngle = acos( -tol / radius + 1 );
increment = 2 * halfAngle;
LWDEBUGF(2, "lwarc_linearize: maxDiff:%g, radius:%g, halfAngle:%g, increment:%g (%g degrees)", tol, radius, halfAngle, increment, increment*180/M_PI);
}}
else if ( tolerance_type == LW_LINEARIZE_TOLERANCE_TYPE_MAX_ANGLE )
{
increment = tol;
if ( increment <= 0 )
{
lwerror("lwarc_linearize: max angle must be bigger than 0, got %.15g", tol);
return -1;
}
}
else
{
lwerror("lwarc_linearize: unsupported tolerance type %d", tolerance_type);
return LW_FALSE;
}
/* Angles of each point that defines the arc section */
a1 = atan2(p1->y - center.y, p1->x - center.x);
a2 = atan2(p2->y - center.y, p2->x - center.x);
a3 = atan2(p3->y - center.y, p3->x - center.x);
LWDEBUGF(2, "lwarc_linearize A1:%g (%g) A2:%g (%g) A3:%g (%g)",
a1, a1*180/M_PI, a2, a2*180/M_PI, a3, a3*180/M_PI);
if ( flags & LW_LINEARIZE_FLAG_SYMMETRIC )
{{
/* Calculate total arc angle, in radians */
double angle = clockwise ? a1 - a3 : a3 - a1;
if ( angle < 0 ) angle += M_PI * 2;
LWDEBUGF(2, "lwarc_linearize SYMMETRIC requested - total angle %g deg",
angle * 180 / M_PI);
if ( flags & LW_LINEARIZE_FLAG_RETAIN_ANGLE )
{{
/* Number of steps */
int steps = trunc(angle / increment);
/* Angle reminder */
double angle_reminder = angle - ( increment * steps );
angle_shift = angle_reminder / 2.0;
LWDEBUGF(2, "lwarc_linearize RETAIN_ANGLE operation requested - "
"total angle %g, steps %d, increment %g, reminder %g",
angle * 180 / M_PI, steps, increment * 180 / M_PI,
angle_reminder * 180 / M_PI);
}}
else
{{
/* Number of segments in output */
int segs = ceil(angle / increment);
/* Tweak increment to be regular for all the arc */
increment = angle/segs;
LWDEBUGF(2, "lwarc_linearize SYMMETRIC operation requested - "
"total angle %g degrees - LINESTRING(%g %g,%g %g,%g %g) - S:%d - I:%g",
angle*180/M_PI, p1->x, p1->y, center.x, center.y, p3->x, p3->y,
segs, increment*180/M_PI);
}}
}}
/* p2 on left side => clockwise sweep */
if ( clockwise )
{
LWDEBUG(2, " Clockwise sweep");
increment *= -1;
angle_shift *= -1;
/* Adjust a3 down so we can decrement from a1 to a3 cleanly */
if ( a3 > a1 )
a3 -= 2.0 * M_PI;
if ( a2 > a1 )
a2 -= 2.0 * M_PI;
}
/* p2 on right side => counter-clockwise sweep */
else
{
LWDEBUG(2, " Counterclockwise sweep");
/* Adjust a3 up so we can increment from a1 to a3 cleanly */
if ( a3 < a1 )
a3 += 2.0 * M_PI;
if ( a2 < a1 )
a2 += 2.0 * M_PI;
}
/* Override angles for circle case */
if( is_circle )
{
a3 = a1 + 2.0 * M_PI;
a2 = a1 + M_PI;
increment = fabs(increment);
clockwise = LW_FALSE;
}
LWDEBUGF(2, "lwarc_linearize angle_shift:%g, increment:%g",
angle_shift * 180/M_PI, increment * 180/M_PI);
if ( reverse ) {{
const int capacity = 8; /* TODO: compute exactly ? */
pa = ptarray_construct_empty(ptarray_has_z(to), ptarray_has_m(to), capacity);
}}
/* Sweep from a1 to a3 */
if ( ! reverse )
{
ptarray_append_point(pa, p1, LW_FALSE);
}
++points_added;
if ( angle_shift ) angle_shift -= increment;
LWDEBUGF(2, "a1:%g (%g deg), a3:%g (%g deg), inc:%g, shi:%g, cw:%d",
a1, a1 * 180 / M_PI, a3, a3 * 180 / M_PI, increment, angle_shift, clockwise);
for ( angle = a1 + increment + angle_shift; clockwise ? angle > a3 : angle < a3; angle += increment )
{
LWDEBUGF(2, " SA: %g ( %g deg )", angle, angle*180/M_PI);
pt.x = center.x + radius * cos(angle);
pt.y = center.y + radius * sin(angle);
pt.z = interpolate_arc(angle, a1, a2, a3, p1->z, p2->z, p3->z);
pt.m = interpolate_arc(angle, a1, a2, a3, p1->m, p2->m, p3->m);
ptarray_append_point(pa, &pt, LW_FALSE);
++points_added;
angle_shift = 0;
}
if ( reverse ) {{
int i;
ptarray_append_point(to, p3, LW_FALSE);
for ( i=pa->npoints; i>0; i-- ) {
getPoint4d_p(pa, i-1, &pt);
ptarray_append_point(to, &pt, LW_FALSE);
}
ptarray_free(pa);
}}
return points_added;
}
