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Merge pull request #185 from mapbox/line-polygons

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Silently drop zero-area polygons instead of showing Clipper errors
This commit is contained in:
Eric Fischer
2016-03-10 17:31:47 -08:00
parent 652abc9a62 7896c3c2c9
commit c66fd315e1
1 changed files with 34 additions and 4 deletions
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geometry.cc
+34 -4
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@@ -241,6 +241,8 @@ static void decode_clipped(ClipperLib::PolyNode *t, drawvec &out) {
drawvec clean_or_clip_poly(drawvec &geom, int z, int detail, int buffer, bool clip) {
ClipperLib::Clipper clipper(ClipperLib::ioStrictlySimple);
bool has_area = false;
for (unsigned i = 0; i < geom.size(); i++) {
if (geom[i].op == VT_MOVETO) {
unsigned j;
@@ -250,6 +252,16 @@ drawvec clean_or_clip_poly(drawvec &geom, int z, int detail, int buffer, bool cl
}
}
double area = 0;
for (unsigned k = i; k < j; k++) {
area += (long double) geom[k].x * (long double) geom[i + ((k - i + 1) % (j - i))].y;
area -= (long double) geom[k].y * (long double) geom[i + ((k - i + 1) % (j - i))].x;
}
area = area / 2;
if (area != 0) {
has_area = true;
}
ClipperLib::Path path;
drawvec tmp;
@@ -297,6 +309,11 @@ drawvec clean_or_clip_poly(drawvec &geom, int z, int detail, int buffer, bool cl
fprintf(stderr, "Polygon clip failed\n");
}
} else {
if (!has_area) {
drawvec out;
return out;
}
if (!clipper.Execute(ClipperLib::ctUnion, clipped)) {
fprintf(stderr, "Polygon clean failed\n");
}
@@ -978,16 +995,29 @@ std::vector<drawvec> chop_polygon(std::vector<drawvec> &geoms) {
midx /= count;
midy /= count;
drawvec c1, c2;
if (maxy - miny > maxx - minx) {
// printf("clipping y to %lld %lld %lld %lld\n", minx, miny, maxx, midy);
out.push_back(simple_clip_poly(geoms[i], minx, miny, maxx, midy));
c1 = simple_clip_poly(geoms[i], minx, miny, maxx, midy);
// printf(" and %lld %lld %lld %lld\n", minx, midy, maxx, maxy);
out.push_back(simple_clip_poly(geoms[i], minx, midy, maxx, maxy));
c2 = simple_clip_poly(geoms[i], minx, midy, maxx, maxy);
} else {
// printf("clipping x to %lld %lld %lld %lld\n", minx, miny, midx, maxy);
out.push_back(simple_clip_poly(geoms[i], minx, miny, midx, maxy));
c1 = simple_clip_poly(geoms[i], minx, miny, midx, maxy);
// printf(" and %lld %lld %lld %lld\n", midx, midy, maxx, maxy);
out.push_back(simple_clip_poly(geoms[i], midx, miny, maxx, maxy));
c2 = simple_clip_poly(geoms[i], midx, miny, maxx, maxy);
}
if (c1.size() >= geoms[i].size()) {
fprintf(stderr, "Subdividing complex polygon failed\n");
} else {
out.push_back(c1);
}
if (c2.size() >= geoms[i].size()) {
fprintf(stderr, "Subdividing complex polygon failed\n");
} else {
out.push_back(c2);
}
again = true;