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import {
polygonContains as d3PolygonContains,
polygonCentroid as d3PolygonCentroid
} from 'd3-polygon';
export default function () {
//begin: internals
var startAngle = 0;
var clippingPolygon,
dataArray,
dataArrayLength,
clippingPolygonCentroid,
halfIncircleRadius,
angleBetweenData;
//end: internals
///////////////////////
///////// API /////////
///////////////////////
function _pie(d, i, arr, voronoiMapSimulation) {
var shouldUpdateInternals = false;
if (clippingPolygon !== voronoiMapSimulation.clip()) {
clippingPolygon = voronoiMapSimulation.clip();
shouldUpdateInternals |= true;
}
if (dataArray !== arr) {
dataArray = arr;
shouldUpdateInternals |= true;
}
if (shouldUpdateInternals) {
updateInternals();
}
// add some randomness to prevent colinear/cocircular points
// substract -0.5 so that the average jitter is still zero
return [
clippingPolygonCentroid[0] + Math.cos(startAngle + i * angleBetweenData) * halfIncircleRadius + (voronoiMapSimulation.prng()() - 0.5) * 1E-3,
clippingPolygonCentroid[1] + Math.sin(startAngle + i * angleBetweenData) * halfIncircleRadius + (voronoiMapSimulation.prng()() - 0.5) * 1E-3
];
};
_pie.startAngle = function (_) {
if (!arguments.length) {
return startAngle;
}
startAngle = _;
return _pie;
};
///////////////////////
/////// Private ///////
///////////////////////
function updateInternals() {
clippingPolygonCentroid = d3PolygonCentroid(clippingPolygon);
halfIncircleRadius = computeMinDistFromEdges(clippingPolygonCentroid, clippingPolygon) / 2;
dataArrayLength = dataArray.length;
angleBetweenData = 2 * Math.PI / dataArrayLength;
};
function computeMinDistFromEdges(vertex, clippingPolygon) {
var minDistFromEdges = Infinity,
edgeIndex = 0,
edgeVertex0 = clippingPolygon[clippingPolygon.length - 1],
edgeVertex1 = clippingPolygon[edgeIndex];
var distFromCurrentEdge;
while (edgeIndex < clippingPolygon.length) {
distFromCurrentEdge = vDistance(vertex, edgeVertex0, edgeVertex1);
if (distFromCurrentEdge < minDistFromEdges) {
minDistFromEdges = distFromCurrentEdge;
}
edgeIndex++;
edgeVertex0 = edgeVertex1;
edgeVertex1 = clippingPolygon[edgeIndex];
}
return minDistFromEdges;
}
//from https://stackoverflow.com/questions/849211/shortest-distance-between-a-point-and-a-line-segment
function vDistance(vertex, edgeVertex0, edgeVertex1) {
var x = vertex[0],
y = vertex[1],
x1 = edgeVertex0[0],
y1 = edgeVertex0[1],
x2 = edgeVertex1[0],
y2 = edgeVertex1[1];
var A = x - x1,
B = y - y1,
C = x2 - x1,
D = y2 - y1;
var dot = A * C + B * D;
var len_sq = C * C + D * D;
var param = -1;
if (len_sq != 0) //in case of 0 length line
param = dot / len_sq;
var xx, yy;
if (param < 0) { // this should not arise as clippingpolygon is convex
xx = x1;
yy = y1;
} else if (param > 1) { // this should not arise as clippingpolygon is convex
xx = x2;
yy = y2;
} else {
xx = x1 + param * C;
yy = y1 + param * D;
}
var dx = x - xx;
var dy = y - yy;
return Math.sqrt(dx * dx + dy * dy);
}
return _pie;
}