d3.geo.bonne = function() {

  var scale = 200,

      translate = [480, 250],

      x0, // origin longitude in radians

      y0, // origin latitude in radians

      y1, // parallel latitude in radians

      c1; // cot(y1)

  function bonne(coordinates) {

    var x = coordinates[0] * d3_geo_radians - x0,

        y = coordinates[1] * d3_geo_radians - y0;

    if (y1) {

      var p = c1 + y1 - y, E = x * Math.cos(y) / p;

      x = p * Math.sin(E);

      y = p * Math.cos(E) - c1;

    } else {

      x *= Math.cos(y);

      y *= -1;

    }

    return [

      scale * x + translate[0],

      scale * y + translate[1]

    ];

  }

  bonne.invert = function(coordinates) {

    var x = (coordinates[0] - translate[0]) / scale,

        y = (coordinates[1] - translate[1]) / scale;

    if (y1) {

      var c = c1 + y, p = Math.sqrt(x * x + c * c);

      y = c1 + y1 - p;

      x = x0 + p * Math.atan2(x, c) / Math.cos(y);

    } else {

      y *= -1;

      x /= Math.cos(y);

    }

    return [

      x / d3_geo_radians,

      y / d3_geo_radians

    ];

  };

  // 90° for Werner, 0° for Sinusoidal

  bonne.parallel = function(x) {

    if (!arguments.length) return y1 / d3_geo_radians;

    c1 = 1 / Math.tan(y1 = x * d3_geo_radians);

    return bonne;

  };

  bonne.origin = function(x) {

    if (!arguments.length) return [x0 / d3_geo_radians, y0 / d3_geo_radians];

    x0 = x[0] * d3_geo_radians;

    y0 = x[1] * d3_geo_radians;

    return bonne;

  };

  bonne.scale = function(x) {

    if (!arguments.length) return scale;

    scale = +x;

    return bonne;

  };

  bonne.translate = function(x) {

    if (!arguments.length) return translate;

    translate = [+x[0], +x[1]];

    return bonne;

  };

  return bonne.origin([0, 0]).parallel(45);

};