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Don't let polygons with nonzero area disappear during cleaning

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If they collapse, turn them into placeholder squares with the
appropriate area so that there aren't visible coverage gaps.
This commit is contained in:
Eric Fischer
2016-05-05 13:42:32 -07:00
parent fa523bff2b
commit 5cc6d97d9f
6 changed files with 206 additions and 6 deletions
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tile.cpp
+56 -5
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@@ -394,6 +394,47 @@ struct partial_arg {
int tasks;
};
drawvec revive_polygon(drawvec &geom, double area, int z, int detail) {
// From area in world coordinates to area in tile coordinates
long long divisor = 1LL << (32 - detail - z);
area /= divisor * divisor;
if (area == 0) {
return drawvec();
}
int height = ceil(sqrt(area));
int width = round(area / height);
if (width == 0) {
width = 1;
}
long long sx = 0, sy = 0, n = 0;
for (size_t i = 0; i < geom.size(); i++) {
if (geom[i].op == VT_MOVETO || geom[i].op == VT_LINETO) {
sx += geom[i].x;
sy += geom[i].y;
n++;
}
}
if (n > 0) {
sx /= n;
sy /= n;
drawvec out;
out.push_back(draw(VT_MOVETO, sx - (width / 2), sy - (height / 2)));
out.push_back(draw(VT_LINETO, sx - (width / 2) + width, sy - (height / 2)));
out.push_back(draw(VT_LINETO, sx - (width / 2) + width, sy - (height / 2) + height));
out.push_back(draw(VT_LINETO, sx - (width / 2), sy - (height / 2) + height));
out.push_back(draw(VT_LINETO, sx - (width / 2), sy - (height / 2)));
return out;
} else {
return drawvec();
}
}
void *partial_feature_worker(void *v) {
struct partial_arg *a = (struct partial_arg *) v;
std::vector<struct partial> *partials = a->partials;
@@ -408,13 +449,22 @@ void *partial_feature_worker(void *v) {
int *additional = (*partials)[i].additional;
int maxzoom = (*partials)[i].maxzoom;
double area = 0;
if (t == VT_POLYGON) {
area = get_area(geom, 0, geom.size());
}
if ((t == VT_LINE || t == VT_POLYGON) && !(prevent[P_SIMPLIFY] || (z == maxzoom && prevent[P_SIMPLIFY_LOW]))) {
if (1 /* !reduced */) { // XXX why did this not simplify if reduced?
if (t == VT_LINE) {
geom = remove_noop(geom, t, 32 - z - line_detail);
}
geom = simplify_lines(geom, z, line_detail, !(prevent[P_CLIPPING] || prevent[P_DUPLICATION]));
drawvec ngeom = simplify_lines(geom, z, line_detail, !(prevent[P_CLIPPING] || prevent[P_DUPLICATION]));
if (t != VT_POLYGON || ngeom.size() >= 3) {
geom = ngeom;
}
}
}
@@ -441,14 +491,15 @@ void *partial_feature_worker(void *v) {
// Scaling may have made the polygon degenerate.
// Give Clipper a chance to try to fix it.
for (size_t g = 0; g < geoms.size(); g++) {
drawvec before;
if (additional[A_DEBUG_POLYGON]) {
before = geoms[g];
}
drawvec before = geoms[g];
geoms[g] = clean_or_clip_poly(geoms[g], 0, 0, 0, false);
if (additional[A_DEBUG_POLYGON]) {
check_polygon(geoms[g], before);
}
if (geoms[g].size() < 3) {
geoms[g] = revive_polygon(before, area / geoms.size(), z, line_detail);
}
}
}