Show HN: A Rogue State Along Two Rivers(nytimes.com)

    // φ is the central meridian (e.g., 45° for UTM Zone 38)
    // θ is the screen rotation
    function rotatedTransverseMercator(φ, θ) {
      var π = Math.PI,
          cosθ = Math.cos(θ = -(90 + θ) / 180 * π),
          sinθ = Math.sin(θ);
    
      function raw(λ, φ) {
        var x = λ,
            y = Math.log(Math.tan(π / 4 + φ / 2));
        return [
          x * cosθ - y * sinθ,
          x * sinθ + y * cosθ
        ];
      }

      raw.invert = function(x, y) {
        return [
          x * cosθ + y * sinθ,
          2 * Math.atan(Math.exp(y * cosθ - x * sinθ)) - π / 2
        ];
      };

      var rotate = [-φ, 0, 90],
          rotation = d3.geo.rotation(rotate),
          projection = d3.geo.projection(raw).rotate(rotate),
          center = projection.center;

      projection.center = function(_) {
        return _
            ? center(rotation(_))
            : ((_ = center()), rotation.invert(_));
      };
    
      delete projection.rotate;
      return projection;
    }