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Copy pathcircle.js
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142 lines (117 loc) · 3.87 KB
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// TODO breakAtDateLine?
d3.geo.circle = function() {
var origin = [0, 0],
degrees = 90 - 1e-2,
radians = degrees * d3_geo_radians,
arc = d3.geo.greatArc().source(origin).target(d3_identity);
function circle() {
// TODO render a circle as a Polygon
}
function visible(point) {
return arc.distance(point) < radians;
}
circle.clip = function(d) {
if (typeof origin === "function") arc.source(origin.apply(this, arguments));
return clipType(d) || null;
};
var clipType = d3_geo_type({
FeatureCollection: function(o) {
var features = o.features.map(clipType).filter(d3_identity);
return features && (o = Object.create(o), o.features = features, o);
},
Feature: function(o) {
var geometry = clipType(o.geometry);
return geometry && (o = Object.create(o), o.geometry = geometry, o);
},
Point: function(o) {
return visible(o.coordinates) && o;
},
MultiPoint: function(o) {
var coordinates = o.coordinates.filter(visible);
return coordinates.length && {
type: o.type,
coordinates: coordinates
};
},
LineString: function(o) {
var coordinates = clip(o.coordinates);
return coordinates.length && (o = Object.create(o), o.coordinates = coordinates, o);
},
MultiLineString: function(o) {
var coordinates = o.coordinates.map(clip).filter(function(d) { return d.length; });
return coordinates.length && (o = Object.create(o), o.coordinates = coordinates, o);
},
Polygon: function(o) {
var coordinates = o.coordinates.map(clip);
return coordinates[0].length && (o = Object.create(o), o.coordinates = coordinates, o);
},
MultiPolygon: function(o) {
var coordinates = o.coordinates.map(function(d) { return d.map(clip); }).filter(function(d) { return d[0].length; });
return coordinates.length && (o = Object.create(o), o.coordinates = coordinates, o);
},
GeometryCollection: function(o) {
var geometries = o.geometries.map(clipType).filter(d3_identity);
return geometries.length && (o = Object.create(o), o.geometries = geometries, o);
}
});
function clip(coordinates) {
var i = -1,
n = coordinates.length,
clipped = [],
p0,
p1,
p2,
d0,
d1;
while (++i < n) {
d1 = arc.distance(p2 = coordinates[i]);
if (d1 < radians) {
if (p1) clipped.push(d3_geo_greatArcInterpolate(p1, p2)((d0 - radians) / (d0 - d1)));
clipped.push(p2);
p0 = p1 = null;
} else {
p1 = p2;
if (!p0 && clipped.length) {
clipped.push(d3_geo_greatArcInterpolate(clipped[clipped.length - 1], p1)((radians - d0) / (d1 - d0)));
p0 = p1;
}
}
d0 = d1;
}
// Close the clipped polygon if necessary.
p0 = coordinates[0];
p1 = clipped[0];
if (p1 && p2[0] === p0[0] && p2[1] === p0[1] && !(p2[0] === p1[0] && p2[1] === p1[1])) {
clipped.push(p1);
}
return resample(clipped);
}
// Resample coordinates, creating great arcs between each.
function resample(coordinates) {
var i = 0,
n = coordinates.length,
j,
m,
resampled = n ? [coordinates[0]] : coordinates,
resamples,
origin = arc.source();
while (++i < n) {
resamples = arc.source(coordinates[i - 1])(coordinates[i]).coordinates;
for (j = 0, m = resamples.length; ++j < m;) resampled.push(resamples[j]);
}
arc.source(origin);
return resampled;
}
circle.origin = function(x) {
if (!arguments.length) return origin;
origin = x;
if (typeof origin !== "function") arc.source(origin);
return circle;
};
circle.angle = function(x) {
if (!arguments.length) return degrees;
radians = (degrees = +x) * d3_geo_radians;
return circle;
};
return d3.rebind(circle, arc, "precision");
}