Shading of viscircles weird behavior

When I export a figure via

exportgraphics(axis,filename);

multiple times, I get the strange behavior that after some exports circles drawn via

viscircles(axis,[x, y],r,'EnhanceVisibility',true);

are shaded white (just the white circle remains which is shaded to improve visibility).

This worked fine for weeks, but now I added the yellow surface-plot below and now this behavior appears.

Can someone explain why this happens and what to do that the export works (while 'EnhanceVisibility', true remains)?

[Milan Bansal]

Hi @ludolfusexe

Can you please provide the code to reproduce the issue.

Answer 1

[Walter Roberson]

viscircles() uses 2D coordinates, with an implicit ZData of 0.

When you draw a surface, the surface has 3D coordinates.

When 2D data and 3D data are mixed, there are several possible outcomes:

• the object that is drawn later "wins" at Z coordinate 0
• the 3D object "wins" at Z coordinate 0
• the 2D object "wins" at Z coordinate 0
• the 2D object "wins" everywhere, drawn "on top" of the 3D object no matter what the 3D coordinates are
• the 3D object "wins" everwhere, hiding the 2D object everywhere

In practice, this is controlled by the axes SortMethod property

https://blogs.mathworks.com/graphics/2014/11/04/sortmethod/

the default of which is "depth". But "depth" doesn't talk explicitly about what happens for 2D objects (are they treated as 3D with Z = 0?) versus 3D objects, and does not talk explicitly about what happens when there is a surface and a line at the same depth. In practice 2D objects are not always treated the same way as Z = 0...

To be safer, you should switch your viscircles() into plot3() calls with Z = 0.

[ludolfusexe]

Thank you for your explanation.

FYI, all z-codinates of the surface-plot are negative, only the order of the internal viscircles circles seems to be confused by the surface-plot.

I will probably replace viscircles with my own method as you suggested, thank you very much.

[ludolfusexe]

This behavior does not occur in normal plots in the matlab figure, only in the automatically exported png image.