Function circleStream

docs/app/js/sanddance-app.js:132403–132422

(stream, radius, delta, direction, t0, t1)

var _mathJs = require("./math.js");
var _rotationJs = require("./rotation.js");
function circleStream(stream, radius, delta, direction, t0, t1) {
    if (!delta) return;
    var cosRadius = (0, _mathJs.cos)(radius), sinRadius = (0, _mathJs.sin)(radius), step = direction * delta;
    if (t0 == null) {
        t0 = radius + direction * (0, _mathJs.tau);
        t1 = radius - step / 2;
    } else {
        t0 = circleRadius(cosRadius, t0);
        t1 = circleRadius(cosRadius, t1);
        if (direction > 0 ? t0 < t1 : t0 > t1) t0 += direction * (0, _mathJs.tau);
    }
    for(var point, t = t0; direction > 0 ? t > t1 : t < t1; t -= step){
        point = (0, _cartesianJs.spherical)([
            cosRadius,
            -sinRadius * (0, _mathJs.cos)(t),
            -sinRadius * (0, _mathJs.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 = (0, _cartesianJs.cartesian)(point), point[0] -= cosRadius;