Volume on non-uniform grid does not appear

Plotting a 3D volume with a non-uniform grid yields a blank canvas with only the axes and the side bar.

Non-uniform means that the x, y, and z parameters are not simply obtained from a call to mgrid. For my application, they correspond to an affine transformation of such a regular grid, exactly like in https://community.plotly.com/t/3d-volume-plotting-with-non-orthogonal-grid/51662. There is also a StackOverflow answer pointing to this problem: https://stackoverflow.com/questions/66141821/plotting-a-3d-volume-plot-in-r-using-discrete-3d-points#answers.

This is either a bug or simply a documentation mistake, since the reference explicitly states that the coordinates should come from a "uniform or non-uniform 3-D grid" (see https://plotly.com/javascript/reference/volume/#volume).

Reproducer: https://codepen.io/Liozou/pen/OJaQMzK. On the left, the expected behavior, working on a uniform grid. On the right, the issue, on an affine-transformed grid. Black dots are used to visualize the grid itself.

Commencez par le reproducer CodePen lié et comparez les cas de grille uniforme et de transformation affine dans la trace du volume. Lisez la référence du volume, en particulier ses exigences en matière de coordonnées, puis suivez le point d’entrée du rendu du volume afin d’identifier pourquoi la grille non uniforme produit un canvas vide. Le travail est terminé lorsque le volume transformé de manière affine est rendu, tout en conservant le comportement existant de la grille uniforme.