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Use Clipper for polygon clipping instead of my own implementation

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This commit is contained in:
Eric Fischer
2015-10-13 17:25:01 -07:00
parent 77b451f2c8
commit 2b25c2fe3e
6 changed files with 5359 additions and 14 deletions
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geometry.cc
+68 -13
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@@ -10,6 +10,7 @@
#include <sqlite3.h>
#include <limits.h>
#include "geometry.hh"
#include "clipper/clipper.hpp"
extern "C" {
#include "tile.h"
@@ -206,6 +207,7 @@ drawvec shrink_lines(drawvec &geom, int z, int detail, int basezoom, long long *
}
#endif
#if 0
static bool inside(draw d, int edge, long long area, long long buffer) {
long long clip_buffer = buffer * area / 256;
@@ -321,13 +323,40 @@ static drawvec clip_poly1(drawvec &geom, int z, int detail, int buffer) {
return out;
}
#endif
drawvec clip_poly(drawvec &geom, int z, int detail, int buffer) {
if (z == 0) {
return geom;
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
// to do any outer-ring children of those children as a new top level.
ClipperLib::Path p = t->Contour;
for (int i = 0; i < p.size(); i++) {
out.push_back(draw((i == 0) ? VT_MOVETO : VT_LINETO, p[i].X, p[i].Y));
}
if (p.size() > 0) {
out.push_back(draw(VT_LINETO, p[0].X, p[0].Y));
}
drawvec out;
for (int n = 0; n < t->ChildCount(); n++) {
ClipperLib::Path p = t->Childs[n]->Contour;
for (int i = 0; i < p.size(); i++) {
out.push_back(draw((i == 0) ? VT_MOVETO : VT_LINETO, p[i].X, p[i].Y));
}
if (p.size() > 0) {
out.push_back(draw(VT_LINETO, p[0].X, p[0].Y));
}
}
for (int n = 0; n < t->ChildCount(); n++) {
for (int m = 0; m < t->Childs[n]->ChildCount(); m++) {
decode_clipped(t->Childs[n]->Childs[m], out);
}
}
}
drawvec clip_poly(drawvec &geom, int z, int detail, int buffer) {
ClipperLib::Clipper clipper(ClipperLib::ioStrictlySimple);
for (unsigned i = 0; i < geom.size(); i++) {
if (geom[i].op == VT_MOVETO) {
@@ -338,19 +367,19 @@ drawvec clip_poly(drawvec &geom, int z, int detail, int buffer) {
}
}
ClipperLib::Path path;
drawvec tmp;
for (unsigned k = i; k < j; k++) {
tmp.push_back(geom[k]);
path.push_back(ClipperLib::IntPoint(geom[k].x, geom[k].y));
}
tmp = clip_poly1(tmp, z, detail, buffer);
if (tmp.size() > 0) {
if (tmp[0].x != tmp[tmp.size() - 1].x || tmp[0].y != tmp[tmp.size() - 1].y) {
fprintf(stderr, "Internal error: Polygon ring not closed\n");
exit(EXIT_FAILURE);
if (!clipper.AddPath(path, ClipperLib::ptSubject, true)) {
fprintf(stderr, "Couldn't add polygon for clipping:");
for (unsigned k = i; k < j; k++) {
fprintf(stderr, " %lld,%lld", geom[k].x, geom[k].y);
}
}
for (unsigned k = 0; k < tmp.size(); k++) {
out.push_back(tmp[k]);
fprintf(stderr, "\n");
}
i = j - 1;
@@ -360,6 +389,32 @@ drawvec clip_poly(drawvec &geom, int z, int detail, int buffer) {
}
}
long long area = 0xFFFFFFFF;
if (z != 0) {
area = 1LL << (32 - z);
}
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));
clipper.AddPath(edge, ClipperLib::ptClip, true);
ClipperLib::PolyTree clipped;
if (!clipper.Execute(ClipperLib::ctIntersection, clipped)) {
fprintf(stderr, "Polygon clip failed\n");
}
drawvec out;
for (int i = 0; i < clipped.ChildCount(); i++) {
decode_clipped(clipped.Childs[i], out);
}
return out;
}