1
0
mirror of git://projects.qi-hardware.com/cae-tools.git synced 2024-12-23 04:13:20 +02:00

poly2d/: automatically switch between clockwise and counter-clockwise polygons

The only functions that care about this at the moment are from CGAL,
and there we can determine from context what to do.
This commit is contained in:
Werner Almesberger 2012-05-07 22:12:21 -03:00
parent dfa85075e8
commit 46c8f8653c
5 changed files with 44 additions and 21 deletions

View File

@ -16,23 +16,22 @@ operation in cameo. Later, poly2d could replace more parts of
cameo.
poly2d puts more emphasis on simplicity than on performance. Some
functions expect clockwise closed polygons that don't self-intersect.
functions expect closed polygons that don't self-intersect. For now,
it doesn't matter whether polygons are clockwise or counter-clockwise.
The table below shows the capabilities
Open Counter-clockwise
| Concave Min. vertices
Open Min. vertices
| Concave
| | Self-intersect
| | | | |
Y Y Y Y 0 p2d_contains_poly(b), p2d_free, p2d_free_all,
p2d_is_closed, p2d_copy, p2d_reverse, p2d_vertices,
p2d_write_gnuplog, p2d_write_gnuplot_all
Y Y Y Y 1 p2d_read_gnuplot
- Y Y Y 0 p2d_simplify
- Y - Y 3 p2d_is_cw
- Y - - 3 p2d_contains_point, p2d_contains_poly (a),
- Y - # 3 p2d_area*, p2d_offset*
# CGAL uses ccw, poly2d uses cw. Need to switch.
| | | |
Y Y Y 0 p2d_contains_poly(b), p2d_copy, p2d_free, p2d_free_all,
p2d_is_closed, p2d_no_intersect, p2d_reverse,
p2d_vertices, p2d_write_gnuplot, p2d_write_gnuplot_all
Y Y Y 1 p2d_read_gnuplot
- Y Y 0 p2d_simplify
- Y - 3 p2d_is_cw
- Y - 3 p2d_contains_point, p2d_contains_poly (a),
- Y - 3 p2d_area*, p2d_offset*
Not yet implemented:
- p2d_simplify (low priority - the offsetting from CGAL already covers
@ -43,8 +42,6 @@ Not yet specified:
Other:
- change the license from GPL to LGPL
- change ccw to cw
- make sure CGAL is only fed ccw ploygons and cw holes
- transform CGAL's idea of outer polygons into something we can use
- use more meaningful offset/overlap model for area fill
- check for memory leaks

View File

@ -35,7 +35,7 @@ typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
typedef CGAL::Polygon_2<K> Polygon_2;
static inline Polygon_2 p2d_to_P2(const struct p2d *p)
static inline Polygon_2 p2d_to_P2(const struct p2d *p, int ccw)
{
const struct v2d *v;
Polygon_2 np;
@ -46,6 +46,8 @@ static inline Polygon_2 p2d_to_P2(const struct p2d *p)
v = v->next;
}
while (v != p->v);
if (p2d_is_cw(p) == ccw)
np.reverse_orientation();
return np;
}

View File

@ -80,11 +80,11 @@ extern "C" void p2d_area_holes_append(const struct p2d *p,
const struct p2d *h;
assert(p2d_is_closed(p));
Polygon_with_holes poly(p2d_to_P2(p));
Polygon_with_holes poly(p2d_to_P2(p, 1));
for (h = holes; h; h = h->next) {
assert(p2d_is_closed(h));
poly.add_hole(p2d_to_P2(h));
poly.add_hole(p2d_to_P2(h, 0));
}
recurse_area(poly, offset, offset-overlap, last);

View File

@ -50,11 +50,11 @@ extern "C" struct p2d *p2d_offset_holes(const struct p2d *p,
struct p2d *res = NULL, **last = &res;
assert(p2d_is_closed(p));
Polygon_with_holes poly(p2d_to_P2(p));
Polygon_with_holes poly(p2d_to_P2(p, 1));
for (h = holes; h; h = h->next) {
assert(p2d_is_closed(h));
poly.add_hole(p2d_to_P2(h));
poly.add_hole(p2d_to_P2(h, 0));
}
PolygonPtrVector tmp = off > 0 ?

View File

@ -49,4 +49,28 @@ expect <<EOF
EOF
#------------------------------------------------------------------------------
tst "inner offset, polygon cw" <<EOF
struct p2d *p = p2d_new();
struct p2d *q;
p2d_append(p, v2d_new(0, 0));
p2d_append(p, v2d_new(0, 1));
p2d_append(p, v2d_new(2, 1));
p2d_append(p, v2d_new(2, 0));
p2d_close(p);
q = p2d_offset(p, -0.1);
p2d_write_gnuplot(stdout, q);
EOF
expect <<EOF
0.1 0.1
1.9 0.1
1.9 0.9
0.1 0.9
0.1 0.1
EOF
###############################################################################