Tolerate polygon rings with insufficiently many points in input (#175)

* Tolerate polygon rings with insufficiently many points in input

* Fix changelog typo

CHANGELOG.md

@@ -1,3 +1,7 @@
+# 2.38.0
+
+* Tolerate polygon rings with insuffiently many points in input
+
 # 2.37.1
 
 * Reduce maximum memory used for vertex sorting

geometry.cpp

@@ -642,9 +642,9 @@ drawvec fix_polygon(drawvec &geom) {
 
 			// A polygon ring must contain at least three points
 			// (and really should contain four). If this one does
-			// not have enough, avoid a division by zero trying to
+			// not have any, avoid a division by zero trying to
 			// calculate the centroid below.
-			if (j - i < 3) {
+			if (j - i < 1) {
 				i = j - 1;
 				outer = 0;
 				continue;
@@ -661,6 +661,13 @@ drawvec fix_polygon(drawvec &geom) {
 				ring.push_back(ring[0]);
 			}
 
+			// A polygon ring at this point should contain at least four points.
+			// Flesh it out with some vertex copies if it doesn't.
+
+			while (ring.size() < 4) {
+				ring.push_back(ring[0]);
+			}
+
 			// Reverse ring if winding order doesn't match
 			// inner/outer expectation
 

tests/invalid-linestring/out/-z0.json

@@ -0,0 +1,15 @@
+{ "type": "FeatureCollection", "properties": {
+"antimeridian_adjusted_bounds": "1.000000,2.000000,1.000000,2.000000",
+"bounds": "1.000000,2.000000,1.000000,2.000000",
+"center": "1.000000,2.000000,0",
+"description": "tests/invalid-linestring/out/-z0.json.check.mbtiles",
+"format": "pbf",
+"generator_options": "./tippecanoe -q -a@ -f -o tests/invalid-linestring/out/-z0.json.check.mbtiles -z0 tests/invalid-linestring/too-few.json",
+"json": "{\"vector_layers\":[{\"id\":\"toofew\",\"description\":\"\",\"minzoom\":0,\"maxzoom\":0,\"fields\":{}}],\"tilestats\":{\"layerCount\":1,\"layers\":[{\"layer\":\"toofew\",\"count\":1,\"geometry\":\"LineString\",\"attributeCount\":0,\"attributes\":[]}]}}",
+"maxzoom": "0",
+"minzoom": "0",
+"name": "tests/invalid-linestring/out/-z0.json.check.mbtiles",
+"type": "overlay",
+"version": "2"
+}, "features": [
+] }

tests/invalid-linestring/too-few.json

@@ -0,0 +1 @@
+{ "type": "Feature", "properties": {}, "geometry": { "type": "LineString", "coordinates": [ [ 1, 2 ] ] } }

tests/invalid-polygon/in.json

@@ -0,0 +1 @@
+{ "type": "Feature", "properties": { "handle": 717, "block": -1, "etype": 13, "space": 0, "layer": "0", "olinetype": "BYLAYER", "linetype": "", "color": "0,0,0,255", "ocolor": 7, "color24": -1, "transparency": 0, "lweight": -1, "linewidth": 0.0, "ltscale": 1.0, "visible": 1, "thickness": 0.0, "ext": null, "name": "SOLID", "solid": 1, "associative": 0, "hstyle": 1, "hpattern": 1, "doubleflag": 0, "angle": 0.0, "scale": 0.0, "deflines": 0 }, "geometry": { "type": "MultiPolygon", "coordinates": [ [ [ [ -135.2329619, -85.526118 ], [ -135.2329619, -85.526118 ] ] ] ] } }

tests/invalid-polygon/out/-z0.json

@@ -0,0 +1,15 @@
+{ "type": "FeatureCollection", "properties": {
+"antimeridian_adjusted_bounds": "180.000000,85.051129,-180.000000,-85.051129",
+"bounds": "-135.232962,-85.051129,-135.232962,-85.051129",
+"center": "-135.232962,-85.051129,0",
+"description": "tests/invalid-polygon/out/-z0.json.check.mbtiles",
+"format": "pbf",
+"generator_options": "./tippecanoe -q -a@ -f -o tests/invalid-polygon/out/-z0.json.check.mbtiles -z0 tests/invalid-polygon/in.json",
+"json": "{\"vector_layers\":[{\"id\":\"in\",\"description\":\"\",\"minzoom\":0,\"maxzoom\":0,\"fields\":{\"angle\":\"Number\",\"associative\":\"Number\",\"block\":\"Number\",\"color\":\"String\",\"color24\":\"Number\",\"deflines\":\"Number\",\"doubleflag\":\"Number\",\"etype\":\"Number\",\"handle\":\"Number\",\"hpattern\":\"Number\",\"hstyle\":\"Number\",\"layer\":\"String\",\"linetype\":\"String\",\"linewidth\":\"Number\",\"ltscale\":\"Number\",\"lweight\":\"Number\",\"name\":\"String\",\"ocolor\":\"Number\",\"olinetype\":\"String\",\"scale\":\"Number\",\"solid\":\"Number\",\"space\":\"Number\",\"thickness\":\"Number\",\"transparency\":\"Number\",\"visible\":\"Number\"}}],\"tilestats\":{\"layerCount\":1,\"layers\":[{\"layer\":\"in\",\"count\":1,\"geometry\":\"Polygon\",\"attributeCount\":25,\"attributes\":[{\"attribute\":\"angle\",\"count\":1,\"type\":\"number\",\"values\":[0],\"min\":0,\"max\":0},{\"attribute\":\"associative\",\"count\":1,\"type\":\"number\",\"values\":[0],\"min\":0,\"max\":0},{\"attribute\":\"block\",\"count\":1,\"type\":\"number\",\"values\":[-1],\"min\":-1,\"max\":-1},{\"attribute\":\"color\",\"count\":1,\"type\":\"string\",\"values\":[\"0,0,0,255\"]},{\"attribute\":\"color24\",\"count\":1,\"type\":\"number\",\"values\":[-1],\"min\":-1,\"max\":-1},{\"attribute\":\"deflines\",\"count\":1,\"type\":\"number\",\"values\":[0],\"min\":0,\"max\":0},{\"attribute\":\"doubleflag\",\"count\":1,\"type\":\"number\",\"values\":[0],\"min\":0,\"max\":0},{\"attribute\":\"etype\",\"count\":1,\"type\":\"number\",\"values\":[13],\"min\":13,\"max\":13},{\"attribute\":\"handle\",\"count\":1,\"type\":\"number\",\"values\":[717],\"min\":717,\"max\":717},{\"attribute\":\"hpattern\",\"count\":1,\"type\":\"number\",\"values\":[1],\"min\":1,\"max\":1},{\"attribute\":\"hstyle\",\"count\":1,\"type\":\"number\",\"values\":[1],\"min\":1,\"max\":1},{\"attribute\":\"layer\",\"count\":1,\"type\":\"string\",\"values\":[\"0\"]},{\"attribute\":\"linetype\",\"count\":1,\"type\":\"string\",\"values\":[\"\"]},{\"attribute\":\"linewidth\",\"count\":1,\"type\":\"number\",\"values\":[0],\"min\":0,\"max\":0},{\"attribute\":\"ltscale\",\"count\":1,\"type\":\"number\",\"values\":[1],\"min\":1,\"max\":1},{\"attribute\":\"lweight\",\"count\":1,\"type\":\"number\",\"values\":[-1],\"min\":-1,\"max\":-1},{\"attribute\":\"name\",\"count\":1,\"type\":\"string\",\"values\":[\"SOLID\"]},{\"attribute\":\"ocolor\",\"count\":1,\"type\":\"number\",\"values\":[7],\"min\":7,\"max\":7},{\"attribute\":\"olinetype\",\"count\":1,\"type\":\"string\",\"values\":[\"BYLAYER\"]},{\"attribute\":\"scale\",\"count\":1,\"type\":\"number\",\"values\":[0],\"min\":0,\"max\":0},{\"attribute\":\"solid\",\"count\":1,\"type\":\"number\",\"values\":[1],\"min\":1,\"max\":1},{\"attribute\":\"space\",\"count\":1,\"type\":\"number\",\"values\":[0],\"min\":0,\"max\":0},{\"attribute\":\"thickness\",\"count\":1,\"type\":\"number\",\"values\":[0],\"min\":0,\"max\":0},{\"attribute\":\"transparency\",\"count\":1,\"type\":\"number\",\"values\":[0],\"min\":0,\"max\":0},{\"attribute\":\"visible\",\"count\":1,\"type\":\"number\",\"values\":[1],\"min\":1,\"max\":1}]}]}}",
+"maxzoom": "0",
+"minzoom": "0",
+"name": "tests/invalid-polygon/out/-z0.json.check.mbtiles",
+"type": "overlay",
+"version": "2"
+}, "features": [
+] }

version.hpp

@@ -1,6 +1,6 @@
 #ifndef VERSION_HPP
 #define VERSION_HPP
 
-#define VERSION "v2.37.1"
+#define VERSION "v2.38.0"
 
 #endif