錯誤：的值無效 <path> 屬性-在d3投影過渡期間-Infinity和NaN

Question

我正在研究世界互動地圖（縮放+拖動）上的正交投影和墨卡托投影之間的過渡。 我根據@mbostock的答案做出了嘗試。 我的過渡效果很好，但是控制台返回了以下內容：

錯誤：屬性d的值無效=“ M399.97994119370463,631.2543931983346L401.90905516286807,634.6157013775801L402.49382423943246,639.8924592362391L397.1999166487309，.......， InfinityL492，InfinityL298.23496934976544，InfinityZ ”

也

錯誤：屬性d =“ M407.5277462873383,448.4656515493841L407.3237573717514,448.5198670656254L408.0599991645186,448.54332648718287L408.0215749188842,448.4385574971469ZM410.40575858016456,448.5990104765492L410.8017911794915,448.571415 NaNZM415，NaNL415，NaNL415，NaNZM415，NaNL415，449.0295187376797L415,449.0295187376797L414.9999381778805,449.02952802059315L415,449.02952802059315L414.41200773961845 。”。

我使用的是Natural Earth shapefile中的topoJson，每次返回補間函數時，我只會收到這些路徑錯誤之一。 我相信這意味着只有一個路徑元素存在此問題。

這是我在投影類中擁有的轉換方法：

animation(timeout, newProjection) {
  let self = this;
  let projection = this.interpolatedProjection(this.prjFnc, newProjection);
  let path = d3.geo.path().projection(projection);
  this.svg.transition()
    .duration(timeout / 2)
    .tween('projection', function() {
      return function(_) {
        self.alpha(_);
        self.svg.selectAll('path').attr('d', path);
      };
    });
}
interpolatedProjection(a, b) {
  let self = this;
  this.a = a;
  this.b = b;
  this.α = null;
  function raw(λ, φ) {
    let pa = self.a([λ *= 180 / Math.PI, φ *= 180 / Math.PI]), pb = self.b([λ, φ]);
    return [(1 - self.α) * pa[0] + self.α * pb[0], (self.α - 1) * pa[1] - self.α * pb[1]];
  }
  this.intProjection = d3.geo.projection(raw).scale(1);
  this.center = this.intProjection.center;
  this.translate = this.intProjection.translate;
  delete this.intProjection.scale;
  delete this.intProjection.translate;
  delete this.intProjection.center;
  return this.alpha(0.1);
}
alpha(_) {
  if(!arguments.length) {
    return this.α;
  }
  this.α = +_;
  let ca = this.a.center(),
      cb = this.b.center(),
      ta = this.a.translate(),
      tb = this.b.translate();

  this.center(
    [(1 - this.α) * ca[0] + this.α * cb[0],
    (1 - this.α) * ca[1] + this.α * cb[1]]
  );
  this.translate(
    [Math.round((1 - this.α) * ta[0] + this.α * tb[0]),
    Math.round((1 - this.α) * ta[1] + this.α * tb[1])]
  );
  return this.intProjection;
}

有什么想法嗎？

Answer 1

無限誤差是由嘗試在svg外部繪制的路徑引起的。 通過將Clip Extent添加到插值投影中，我能夠消除這些錯誤。

interpolatedProjection(a, b) {
  let self = this;
  this.a = a;
  this.b = b;
  this.α = null;
  function raw(λ, φ) {
    let pa = self.a([λ *= 180 / Math.PI, φ *= 180 / Math.PI]), pb = self.b([λ, φ]);
    return [(1 - self.α) * pa[0] + self.α * pb[0], (self.α - 1) * pa[1] - self.α * pb[1]];
  }
  this.intProjection = d3.geo.projection(raw).scale(1)

    .clipExtent(this.extent); // this addition

  this.center = this.intProjection.center;
  this.translate = this.intProjection.translate;
  delete this.intProjection.scale;
  delete this.intProjection.translate;
  delete this.intProjection.center;
  return this.alpha(0.1);
}

我還在d屬性中收到一個NaN錯誤，通過不讓補間索引達到1可以刪除該錯誤。

animation(timeout, newProjection) {
  let self = this;
  let projection = this.interpolatedProjection(this.prjFnc, newProjection);
  let path = d3.geo.path().projection(projection);
  this.svg.transition()
    .duration(timeout)
    .tween('projection', function() {
      return function(_) {

        if (_ === 1) { return; } // This addition

        self.alpha(_);
        self.paths.attr('d', path);
      };
    });
}