Function clipAntimeridianLine

external/.d3.js:10833–10876

(stream)

// intersections or the line was empty; 1 - no intersections; 2 - there were
// intersections, and the first and last segments should be rejoined.
function clipAntimeridianLine(stream) {
  var lambda0 = NaN,
      phi0 = NaN,
      sign0 = NaN,
      clean; // no intersections

  return {
    lineStart: function() {
      stream.lineStart();
      clean = 1;
    },
    point: function(lambda1, phi1) {
      var sign1 = lambda1 > 0 ? pi$1 : -pi$1,
          delta = abs$1(lambda1 - lambda0);
      if (abs$1(delta - pi$1) < epsilon$1) { // line crosses a pole
        stream.point(lambda0, phi0 = (phi0 + phi1) / 2 > 0 ? halfPi$1 : -halfPi$1);
        stream.point(sign0, phi0);
        stream.lineEnd();
        stream.lineStart();
        stream.point(sign1, phi0);
        stream.point(lambda1, phi0);
        clean = 0;
      } else if (sign0 !== sign1 && delta >= pi$1) { // line crosses antimeridian
        if (abs$1(lambda0 - sign0) < epsilon$1) lambda0 -= sign0 * epsilon$1; // handle degeneracies
        if (abs$1(lambda1 - sign1) < epsilon$1) lambda1 -= sign1 * epsilon$1;
        phi0 = clipAntimeridianIntersect(lambda0, phi0, lambda1, phi1);
        stream.point(sign0, phi0);
        stream.lineEnd();
        stream.lineStart();
        stream.point(sign1, phi0);
        clean = 0;
      }
      stream.point(lambda0 = lambda1, phi0 = phi1);
      sign0 = sign1;
    },
    lineEnd: function() {
      stream.lineEnd();
      lambda0 = phi0 = NaN;
    },
    clean: function() {
      return 2 - clean; // if intersections, rejoin first and last segments
    }
  };
}

function clipAntimeridianIntersect(lambda0, phi0, lambda1, phi1) {
  var cosPhi0,