VMD-L Mailing List

From: Andrew Dalke (dalke_at_bioreason.com)
Date: Fri Sep 18 1998 - 12:32:30 CDT

Siegmar Kardinal <kardinal_at_methin.orc.univie.ac.at> said:
> I would like to draw a semi transparent cylinder or cone but I did not
> succeed with commands like
>
> mol load graphics ska_graph
> graphics top color trans_blue
> color change alpha trans_blue .5
> graphics top cone $from $to radius 0.8
>
> The resulting cone ist blue but not transparent.

What you're seeing is the fact that I don't really know how to do
graphics correctly. The way GL and OpenGL work, you are supposed
to display the transparent items in sorted order; farthest from
the eye point to the nearest. VMD doesn't currently do that.

Luckily, John Stone has taken up main VMD development back at
UIUC, and he know graphics a whole lot more than I do. I believe
fixing this is on his list of things to do.

In the meanwhile, there is an undocumented semi-solution Jeff Ulrich
had added to the GL code to toggle sorted display mode
 "display depthsort on"
but I just tried it out with your example and it doesn't seem to
work. I don't know why, but it was mostly meant for testing
the postscript driver, so it wasn't fully tested. I point this out
only if you want to start modifying code.

So there's currently no way in VMD to do what you want.

                                                Andrew Dalke
                                                dalke_at_bioreason.com