Import Upstream version 1.9.0

1 files changed, 72 insertions, 0 deletions

diff --git a/src/circle.js b/src/circle.js
new file mode 100644
index 0000000..9dbdbef
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+++ b/src/circle.js
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+import {cartesian, cartesianNormalizeInPlace, spherical} from "./cartesian";
+import constant from "./constant";
+import {acos, cos, degrees, epsilon, radians, sin, tau} from "./math";
+import {rotateRadians} from "./rotation";
+
+// Generates a circle centered at [0°, 0°], with a given radius and precision.
+export function circleStream(stream, radius, delta, direction, t0, t1) {
+  if (!delta) return;
+  var cosRadius = cos(radius),
+      sinRadius = sin(radius),
+      step = direction * delta;
+  if (t0 == null) {
+    t0 = radius + direction * tau;
+    t1 = radius - step / 2;
+  } else {
+    t0 = circleRadius(cosRadius, t0);
+    t1 = circleRadius(cosRadius, t1);
+    if (direction > 0 ? t0 < t1 : t0 > t1) t0 += direction * tau;
+  }
+  for (var point, t = t0; direction > 0 ? t > t1 : t < t1; t -= step) {
+    point = spherical([cosRadius, -sinRadius * cos(t), -sinRadius * sin(t)]);
+    stream.point(point[0], point[1]);
+  }
+}
+
+// Returns the signed angle of a cartesian point relative to [cosRadius, 0, 0].
+function circleRadius(cosRadius, point) {
+  point = cartesian(point), point[0] -= cosRadius;
+  cartesianNormalizeInPlace(point);
+  var radius = acos(-point[1]);
+  return ((-point[2] < 0 ? -radius : radius) + tau - epsilon) % tau;
+}
+
+export default function() {
+  var center = constant([0, 0]),
+      radius = constant(90),
+      precision = constant(6),
+      ring,
+      rotate,
+      stream = {point: point};
+
+  function point(x, y) {
+    ring.push(x = rotate(x, y));
+    x[0] *= degrees, x[1] *= degrees;
+  }
+
+  function circle() {
+    var c = center.apply(this, arguments),
+        r = radius.apply(this, arguments) * radians,
+        p = precision.apply(this, arguments) * radians;
+    ring = [];
+    rotate = rotateRadians(-c[0] * radians, -c[1] * radians, 0).invert;
+    circleStream(stream, r, p, 1);
+    c = {type: "Polygon", coordinates: [ring]};
+    ring = rotate = null;
+    return c;
+  }
+
+  circle.center = function(_) {
+    return arguments.length ? (center = typeof _ === "function" ? _ : constant([+_[0], +_[1]]), circle) : center;
+  };
+
+  circle.radius = function(_) {
+    return arguments.length ? (radius = typeof _ === "function" ? _ : constant(+_), circle) : radius;
+  };
+
+  circle.precision = function(_) {
+    return arguments.length ? (precision = typeof _ === "function" ? _ : constant(+_), circle) : precision;
+  };
+
+  return circle;
+}