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More thoughts about clipped polygon topology

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This commit is contained in:
Eric Fischer 2018-04-06 18:02:30 -07:00
parent b90f0b1295
commit 05710feab5
1 changed files with 14 additions and 3 deletions
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17
geometry.cpp
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@ -516,6 +516,9 @@ void push_outward(drawvec &dv, size_t off, int edge, int distance, long long min
static drawvec clip_poly1(drawvec &geom, long long minx, long long miny, long long maxx, long long maxy) {
drawvec out = geom;
// Maybe want to remove the ring-end duplicate terminators
// and do everything modulo the length instead?
for (int edge = 0; edge < 4; edge++) {
if (out.size() > 0) {
drawvec in = out;
@ -558,11 +561,11 @@ static drawvec clip_poly1(drawvec &geom, long long minx, long long miny, long lo
std::multimap<int, size_t> segs_on_edge;
for (size_t i = 1; i < out.size(); i++) {
int len_on_edge = on_edge(out[i - 1], out[i], edge, minx, miny, maxx, maxy);
for (size_t i = 0; i < out.size(); i++) {
int len_on_edge = on_edge(out[i], out[(i + 1) % out.size()], edge, minx, miny, maxx, maxy);
if (len_on_edge > 0) {
segs_on_edge.insert(std::pair<int, size_t>(len_on_edge, i - 1));
segs_on_edge.insert(std::pair<int, size_t>(len_on_edge, i));
}
}
@ -573,6 +576,14 @@ static drawvec clip_poly1(drawvec &geom, long long minx, long long miny, long lo
}
}
// If the innermost edge ring is a hole, and it's entirely
// outside the tile, can we then get rid of all the
// edge rings (and potentially the entire feature, if
// the entire tile is contained within a hole)?
//
// If the hole actually passes through the tile, we still
// need it and whatever its parent ring is.
if (out.size() > 0) {
// If the polygon begins and ends outside the edge,
// the starting and ending points will be left as the