lightposition for surface plots doesn't work

The parameter lightposition for surface plots expects an x, y, z vector. This vector is not explained in the documentation, does not make sense in any way, and playing with it only produces aggravation. It appears to be completely broken. This parameter should be defined in spherical coordinates and explained clearly in the documentation.

Not only does trying different values for x, y, z not make sense, I had a surface plot defined over the domains in x and y (my coordinates) of 0 to 6. I then realized that the domain should be -3 to 3; when I made this change, the lighting changed radically and I can't figure out how to get back the original lighting without reverting to the incorrect domains.

(1) lightposition needs to be fixed.

(2) lightposition needs to be in spherical coordinates.

(3) lightposition needs to be properly documented.

(4) lightposition needs to have at least an option which has a definition in "head" space so that the lighting doesn't change when merely the domain of the data is changed.

首先定位 surface-plot 的 lightposition 入口點及其文件；issue 未指定檔案或測試。重現 x 和 y 域從 0–6 變為 -3–3 時的光照變化，然後定義所需的座標行為。當該參數的行為一致、支援所要求的定位語意，並且有清楚的文件說明時，即可視為完成。