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.

Comienza con el reproductor de CodePen enlazado y compara los casos de cuadrícula uniforme y transformación afín en el trazado del volumen. Lee la referencia del volumen, especialmente sus requisitos de coordenadas, y luego sigue el punto de entrada del renderizado del volumen para identificar por qué la cuadrícula no uniforme produce un canvas en blanco. El trabajo estará terminado cuando el volumen transformado afínmente se renderice y el comportamiento existente de la cuadrícula uniforme permanezca intacto.