abkfenris / sugarloaf

      d3_geo_centroid.lineEnd = d3_geo_centroidLineEnd;

      d3_geo_centroid.point = d3_geo_centroidPoint;

    };

    function nextPoint(λ, φ) {

      λ *= d3_radians;

      var cosφ = Math.cos(φ *= d3_radians), x = cosφ * Math.cos(λ), y = cosφ * Math.sin(λ), z = Math.sin(φ), cx = y0 * z - z0 * y, cy = z0 * x - x0 * z, cz = x0 * y - y0 * x, m = Math.sqrt(cx * cx + cy * cy + cz * cz), u = x0 * x + y0 * y + z0 * z, v = m && -d3_acos(u) / m, w = Math.atan2(m, u);

      d3_geo_centroidX2 += v * cx;

      d3_geo_centroidY2 += v * cy;

      d3_geo_centroidZ2 += v * cz;

      d3_geo_centroidW1 += w;

      d3_geo_centroidX1 += w * (x0 + (x0 = x));

      d3_geo_centroidY1 += w * (y0 + (y0 = y));

      d3_geo_centroidZ1 += w * (z0 + (z0 = z));

      d3_geo_centroidPointXYZ(x0, y0, z0);

    }

  }

  function d3_geo_compose(a, b) {

    function compose(x, y) {

      d3_geo_centroid.point = nextPoint;

      d3_geo_centroidPointXYZ(x0, y0, z0);

    };

    function nextPoint(λ, φ) {

      λ *= d3_radians;

      var cosφ = Math.cos(φ *= d3_radians), x = cosφ * Math.cos(λ), y = cosφ * Math.sin(λ), z = Math.sin(φ), w = Math.atan2(Math.sqrt((w = y0 * z - z0 * y) * w + (w = z0 * x - x0 * z) * w + (w = x0 * y - y0 * x) * w), x0 * x + y0 * y + z0 * z);

      d3_geo_centroidW1 += w;

      d3_geo_centroidX1 += w * (x0 + (x0 = x));

      d3_geo_centroidY1 += w * (y0 + (y0 = y));

      d3_geo_centroidZ1 += w * (z0 + (z0 = z));

      d3_geo_centroidPointXYZ(x0, y0, z0);

    }

  }

  function d3_geo_centroidLineEnd() {

    d3_geo_centroid.point = d3_geo_centroidPoint;