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Fix division by 0 by using more general and robust polygon-checking code

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Eric Fischer
2017-02-17 13:25:56 -08:00
parent 1cc65d61ba
commit 1b68dcdc22
2 changed files with 496 additions and 17 deletions
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geometry.cpp
+30 -17
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@@ -13,6 +13,7 @@
#include <mapbox/geometry/multi_polygon.hpp>
#include <mapbox/geometry/wagyu/wagyu.hpp>
#include <mapbox/geometry/wagyu/quick_clip.hpp>
#include <mapbox/geometry/snap_rounding.hpp>
#include "geometry.hpp"
#include "projection.hpp"
#include "serial.hpp"
@@ -344,29 +345,41 @@ static int pnpoly(drawvec &vert, size_t start, size_t nvert, long long testx, lo
}
void check_polygon(drawvec &geom, drawvec &before) {
for (size_t i = 0; i + 1 < geom.size(); i++) {
for (size_t j = i + 1; j + 1 < geom.size(); j++) {
if (geom[i + 1].op == VT_LINETO && geom[j + 1].op == VT_LINETO) {
double s1_x = geom[i + 1].x - geom[i + 0].x;
double s1_y = geom[i + 1].y - geom[i + 0].y;
double s2_x = geom[j + 1].x - geom[j + 0].x;
double s2_y = geom[j + 1].y - geom[j + 0].y;
geom = remove_noop(geom, VT_POLYGON, 0);
double s, t;
s = (-s1_y * (geom[i + 0].x - geom[j + 0].x) + s1_x * (geom[i + 0].y - geom[j + 0].y)) / (-s2_x * s1_y + s1_x * s2_y);
t = (s2_x * (geom[i + 0].y - geom[j + 0].y) - s2_y * (geom[i + 0].x - geom[j + 0].x)) / (-s2_x * s1_y + s1_x * s2_y);
if (t > 0 && t < 1 && s > 0 && s < 1) {
printf("Internal error: self-intersecting polygon. %lld,%lld to %lld,%lld intersects %lld,%lld to %lld,%lld\n",
geom[i + 0].x, geom[i + 0].y,
geom[i + 1].x, geom[i + 1].y,
geom[j + 0].x, geom[j + 0].y,
geom[j + 1].x, geom[j + 1].y);
mapbox::geometry::multi_polygon<long long> mp;
for (size_t i = 0; i < geom.size(); i++) {
if (geom[i].op == VT_MOVETO) {
size_t j;
for (j = i + 1; j < geom.size(); j++) {
if (geom[j].op != VT_LINETO) {
break;
}
}
if (j >= i + 4) {
mapbox::geometry::linear_ring<long long> lr;
for (size_t k = i; k < j; k++) {
lr.push_back(mapbox::geometry::point<long long>(geom[k].x, geom[k].y));
}
if (lr.size() >= 3) {
mapbox::geometry::polygon<long long> p;
p.push_back(lr);
mp.push_back(p);
}
}
i = j - 1;
}
}
mapbox::geometry::multi_polygon<long long> mp2 = mapbox::geometry::snap_round(mp, true, true);
if (mp != mp2) {
fprintf(stderr, "Internal error: self-intersecting polygon\n");
}
size_t outer_start = -1;
size_t outer_len = 0;