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jasondaviesjasondavies
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Fix path.centroid for polygons with holes.
The centroid was not being subtracted for interior polygon rings (holes), hence it was appearing too far to the right. The winding order is ignored.
1 parent 2eeb205 commit f58b5db

4 files changed

Lines changed: 43 additions & 7 deletions

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‎d3.js‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -6056,11 +6056,11 @@
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return z;
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}
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function ringCentroid(centroid, ring, i) {
6059-
var polygon = d3.geom.polygon(ring.map(projection)), area = polygon.area(), point = polygon.centroid(area < 0 ? (area *= -1,
6060-
1) : -1);
6059+
var polygon = d3.geom.polygon(ring.map(projection)), area = polygon.area();
6060+
var point = polygon.centroid(area < 0 ^ i > 0 ? (area *= -1, 1) : -1);
60616061
centroid[0] += point[0];
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centroid[1] += point[1];
6063-
return area * (i > 0 ? -6 : 6);
6063+
return area * 6;
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}
60656065
path.bounds = function(object) {
60666066
return (bounds || (bounds = d3_geo_bounds(projection)))(object);

‎d3.min.js‎

Lines changed: 1 addition & 1 deletion
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‎src/geo/path.js‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -101,11 +101,11 @@ d3.geo.path = function() {
101101

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function ringCentroid(centroid, ring, i) {
103103
var polygon = d3.geom.polygon(ring.map(projection)),
104-
area = polygon.area(),
105-
point = polygon.centroid(area < 0 ? (area *= -1, 1) : -1);
104+
area = polygon.area();
105+
var point = polygon.centroid(area < 0 ^ i > 0 ? (area *= -1, 1) : -1);
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centroid[0] += point[0];
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centroid[1] += point[1];
108-
return area * (i > 0 ? -6 : 6);
108+
return area * 6;
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}
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111111
path.bounds = function(object) {

‎test/geo/path-test.js‎

Lines changed: 36 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -161,6 +161,42 @@ suite.addBatch({
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},
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"two rings, one zero area": function(centroid) {
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assert.deepEqual(centroid({type: "Polygon", coordinates: [[[100, 0], [101, 0], [101, 1], [100, 1], [100, 0]], [[100.1, 0], [100.2, 0], [100.3, 0], [100.1, 0]]]}), [982.5, 247.5]);
164+
},
165+
"anticlockwise exterior and interior": function(centroid) {
166+
assert.inDelta(centroid({
167+
type: "Polygon",
168+
coordinates: [
169+
[[-2, -2], [2, -2], [2, 2], [-2, 2], [-2, -2]],
170+
[[ 0, -1], [1, -1], [1, 1], [ 0, 1], [ 0, -1]]
171+
]
172+
}), [479.642857, 250], 1e-6);
173+
},
174+
"clockwise exterior and interior": function(centroid) {
175+
assert.inDelta(centroid({
176+
type: "Polygon",
177+
coordinates: [
178+
[[-2, -2], [2, -2], [2, 2], [-2, 2], [-2, -2]].reverse(),
179+
[[ 0, -1], [1, -1], [1, 1], [ 0, 1], [ 0, -1]].reverse()
180+
]
181+
}), [479.642857, 250], 1e-6);
182+
},
183+
"anticlockwise exterior, clockwise interior": function(centroid) {
184+
assert.inDelta(centroid({
185+
type: "Polygon",
186+
coordinates: [
187+
[[-2, -2], [2, -2], [2, 2], [-2, 2], [-2, -2]],
188+
[[ 0, -1], [1, -1], [1, 1], [ 0, 1], [ 0, -1]].reverse()
189+
]
190+
}), [479.642857, 250], 1e-6);
191+
},
192+
"clockwise exterior, anticlockwise interior": function(centroid) {
193+
assert.inDelta(centroid({
194+
type: "Polygon",
195+
coordinates: [
196+
[[-2, -2], [2, -2], [2, 2], [-2, 2], [-2, -2]].reverse(),
197+
[[ 0, -1], [1, -1], [1, 1], [ 0, 1], [ 0, -1]]
198+
]
199+
}), [479.642857, 250], 1e-6);
164200
}
165201
},
166202
"MultiPolygon": {

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