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Offset coordinates for Clipper to keep them positive.

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Limit very high or low latitudes and longitudes.
This commit is contained in:
Eric Fischer 2015-12-08 16:24:17 -08:00
parent bbcf9e1b3c
commit dace304182
2 changed files with 29 additions and 10 deletions
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22
geometry.cc
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@ -206,6 +206,8 @@ drawvec shrink_lines(drawvec &geom, int z, int detail, int basezoom, long long *
}
#endif
#define CLIPPER_OFFSET 0x400000000LL
static void decode_clipped(ClipperLib::PolyNode *t, drawvec &out) {
// To make the GeoJSON come out right, we need to do each of the
// outer rings followed by its children if any, and then go back
@ -213,19 +215,19 @@ static void decode_clipped(ClipperLib::PolyNode *t, drawvec &out) {
ClipperLib::Path p = t->Contour;
for (unsigned i = 0; i < p.size(); i++) {
out.push_back(draw((i == 0) ? VT_MOVETO : VT_LINETO, p[i].X, p[i].Y));
out.push_back(draw((i == 0) ? VT_MOVETO : VT_LINETO, p[i].X - CLIPPER_OFFSET, p[i].Y - CLIPPER_OFFSET));
}
if (p.size() > 0) {
out.push_back(draw(VT_LINETO, p[0].X, p[0].Y));
out.push_back(draw(VT_LINETO, p[0].X - CLIPPER_OFFSET, p[0].Y - CLIPPER_OFFSET));
}
for (int n = 0; n < t->ChildCount(); n++) {
ClipperLib::Path p = t->Childs[n]->Contour;
for (unsigned i = 0; i < p.size(); i++) {
out.push_back(draw((i == 0) ? VT_MOVETO : VT_LINETO, p[i].X, p[i].Y));
out.push_back(draw((i == 0) ? VT_MOVETO : VT_LINETO, p[i].X - CLIPPER_OFFSET, p[i].Y - CLIPPER_OFFSET));
}
if (p.size() > 0) {
out.push_back(draw(VT_LINETO, p[0].X, p[0].Y));
out.push_back(draw(VT_LINETO, p[0].X - CLIPPER_OFFSET, p[0].Y - CLIPPER_OFFSET));
}
}
@ -252,7 +254,7 @@ drawvec clean_or_clip_poly(drawvec &geom, int z, int detail, int buffer, bool cl
drawvec tmp;
for (unsigned k = i; k < j; k++) {
path.push_back(ClipperLib::IntPoint(geom[k].x, geom[k].y));
path.push_back(ClipperLib::IntPoint(geom[k].x + CLIPPER_OFFSET, geom[k].y + CLIPPER_OFFSET));
}
if (!clipper.AddPath(path, ClipperLib::ptSubject, true)) {
@ -280,11 +282,11 @@ drawvec clean_or_clip_poly(drawvec &geom, int z, int detail, int buffer, bool cl
long long clip_buffer = buffer * area / 256;
ClipperLib::Path edge;
edge.push_back(ClipperLib::IntPoint(-clip_buffer, -clip_buffer));
edge.push_back(ClipperLib::IntPoint(area + clip_buffer, -clip_buffer));
edge.push_back(ClipperLib::IntPoint(area + clip_buffer, area + clip_buffer));
edge.push_back(ClipperLib::IntPoint(-clip_buffer, area + clip_buffer));
edge.push_back(ClipperLib::IntPoint(-clip_buffer, -clip_buffer));
edge.push_back(ClipperLib::IntPoint(-clip_buffer + CLIPPER_OFFSET, -clip_buffer + CLIPPER_OFFSET));
edge.push_back(ClipperLib::IntPoint(area + clip_buffer + CLIPPER_OFFSET, -clip_buffer + CLIPPER_OFFSET));
edge.push_back(ClipperLib::IntPoint(area + clip_buffer + CLIPPER_OFFSET, area + clip_buffer + CLIPPER_OFFSET));
edge.push_back(ClipperLib::IntPoint(-clip_buffer + CLIPPER_OFFSET, area + clip_buffer + CLIPPER_OFFSET));
edge.push_back(ClipperLib::IntPoint(-clip_buffer + CLIPPER_OFFSET, -clip_buffer + CLIPPER_OFFSET));
clipper.AddPath(edge, ClipperLib::ptClip, true);
}

17
projection.c
View File

@ -3,6 +3,23 @@
// http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames
void latlon2tile(double lat, double lon, int zoom, long long *x, long long *y) {
// Must limit latitude somewhere to prevent overflow.
// 89.9 degrees latitude is 0.621 worlds beyond the edge of the flat earth,
// hopefully far enough out that there are few expectations about the shape.
if (lat < -89.9) {
lat = -89.9;
}
if (lat > 89.9) {
lat = 89.9;
}
if (lon < -360) {
lon = -360;
}
if (lon > 360) {
lon = 360;
}
double lat_rad = lat * M_PI / 180;
unsigned long long n = 1LL << zoom;