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Silently drop zero-area polygons instead of showing Clipper errors

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This commit is contained in:
Eric Fischer 2016-03-10 16:03:02 -08:00
parent 652abc9a62
commit 7eccc7a758
1 changed files with 17 additions and 0 deletions
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17
geometry.cc
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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");
}