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import "centroid";
// TODO Unify this code with d3.geom.polygon centroid?
// TODO Enforce positive area for exterior, negative area for interior?
var d3_geo_pathCentroid = {
point: d3_geo_pathCentroidPoint,
// For lines, weight by length.
lineStart: d3_geo_pathCentroidLineStart,
lineEnd: d3_geo_pathCentroidLineEnd,
// For polygons, weight by area.
polygonStart: function() {
d3_geo_pathCentroid.lineStart = d3_geo_pathCentroidRingStart;
},
polygonEnd: function() {
d3_geo_pathCentroid.point = d3_geo_pathCentroidPoint;
d3_geo_pathCentroid.lineStart = d3_geo_pathCentroidLineStart;
d3_geo_pathCentroid.lineEnd = d3_geo_pathCentroidLineEnd;
}
};
function d3_geo_pathCentroidPoint(x, y) {
if (d3_geo_centroidDimension) return;
d3_geo_centroidX += x;
d3_geo_centroidY += y;
++d3_geo_centroidZ;
}
function d3_geo_pathCentroidLineStart() {
var x0, y0;
if (d3_geo_centroidDimension !== 1) {
if (d3_geo_centroidDimension < 1) {
d3_geo_centroidDimension = 1;
d3_geo_centroidX = d3_geo_centroidY = d3_geo_centroidZ = 0;
} else return;
}
d3_geo_pathCentroid.point = function(x, y) {
d3_geo_pathCentroid.point = nextPoint;
x0 = x, y0 = y;
};
function nextPoint(x, y) {
var dx = x - x0, dy = y - y0, z = Math.sqrt(dx * dx + dy * dy);
d3_geo_centroidX += z * (x0 + x) / 2;
d3_geo_centroidY += z * (y0 + y) / 2;
d3_geo_centroidZ += z;
x0 = x, y0 = y;
}
}
function d3_geo_pathCentroidLineEnd() {
d3_geo_pathCentroid.point = d3_geo_pathCentroidPoint;
}
function d3_geo_pathCentroidRingStart() {
var x00, y00, x0, y0;
if (d3_geo_centroidDimension < 2) {
d3_geo_centroidDimension = 2;
d3_geo_centroidX = d3_geo_centroidY = d3_geo_centroidZ = 0;
}
// For the first point, …
d3_geo_pathCentroid.point = function(x, y) {
d3_geo_pathCentroid.point = nextPoint;
x00 = x0 = x, y00 = y0 = y;
};
// For subsequent points, …
function nextPoint(x, y) {
var z = y0 * x - x0 * y;
d3_geo_centroidX += z * (x0 + x);
d3_geo_centroidY += z * (y0 + y);
d3_geo_centroidZ += z * 3;
x0 = x, y0 = y;
}
// For the last point, return to the start.
d3_geo_pathCentroid.lineEnd = function() {
nextPoint(x00, y00);
};
}