Allow setting the camera "field of view"

It doesn't seem possible to set the 3D camera field of view (fov).

(Re: my post to Stackoverflow.)

Looking at the source code, I see that:

In https://github.com/plotly/plotly.js/blob/master/src/plots/gl3d/scene.js, it uses glPlot3d.createScene and sets the options in proto.prepareOptions.

In https://github.com/gl-vis/gl-plot3d/blob/master/scene.js#L179, the allowed options include the field-of-view parameter fovy (field-of-view in the vertical direction), which defaults to Math.PI/4 (45 degrees).

For 3D graphics, a 45-degree vertical field-of-view typically gives an exaggerated perspective. It corresponds to about a 28mm camera lens.

It would be nice for plotly.graph_objects.layout.scene.Camera to include a fovy parameter (in radians).

plotly.py の layout.scene.Camera の定義から始め、カメラオプションがどのように plotly.js に渡るかを追跡します。src/plots/gl3d/scene.js、特に proto.prepareOptions を読み、gl-plot3d の scene.js の 179 行目付近にあるオプションと比較します。Python のカメラ API が fovy をラジアン単位で受け付け、3D シーンに渡せるようになれば完了です。