It has been a while (early V6) since this is happening: when Sun and Skylight are enabled, any edges visible through transparent objects disappear or become very faint. It messes things up here, especially the ability to get nice illustration-like viewcaptures with edges, or working in that setup in general.
Any chance we can have that fixed ? @jeff - is that something you can see/replicate?
Here is what I mean:
thanks,
–jarek
Hi @Jarek
Sorry to hi-jack your thread, but what software do you use to make those nice videos?
TIA, Jakob
hi Jakob,
I use Camtasia for screen recordings, and for sharing in the posts here I upload to Screencast free account directly from Camtasia (it is one of the production options). The process is really quick and simple.
hth,
–jarek
I can’t seem to load the video into Rhino and reproduce the problem… 
Seriously though, you should always include your simple model on things like this, and maybe even your display mode exported to .ini file… It just really helps me here on my end so that I don’t always have to try to reproduce the issues from scratch. If you were the only user I had to deal with, then it’d be ok…but there’s at least 1 or 2 more users that I think use Rhino, so including as much as you can in your post knocks down a lot of time on my end… 
Thanks,
-Jeff
No problem; since it happens in all models (video just shows any simple boxes) I skipped the step, sorry. I made two boxes for you (transparent materials and solid) and exported the Rendered mode I am using when seeing this.
SunSkylightEdgeFailSample.zip (43.9 KB)
If this is not just my problem, hope it helps the other 1 or 2 Rhino users out there…
–jarek
Hi @jeff ,
I need to revive this topic and report since in V7 this issue became more important and problematic.
This only happens with Sun + Skylight enabled. Since in V7 it is finally possible to use such setup smoothly thanks to the huge speed improvements you and David E. implemented, we use a mode with Sun+Skylight both as normal real-time modeling mode, and also to produce high quality screen captures, basically WYSIWYG straight from Rhino.
So now this “disappearing edges and curves” behind transparent objects is a big problem, both in modeling, hard to see what’s going on, and also for producing good looking captures. Most of our projects are architectural so naturally there is a lot of glass/transparent materials and geometry to be seen behind the glass… I will PM you some more detailed screenshots showing a specific project and the issue based on that.
Here is a quick new capture from V7 illustrating the same problem reported before:
Here is the display mode (modified Rendered, that shows the edges of surfaces and meshes):
Rendered.ini (13.8 KB)
And the sample file used in the video:
Sun+Skylight_Transparency_Test.3dm (1.9 MB)
Only Sun and Only Skylight don’t have this problem, it’s only an issue when they are both combined. I have a small hope that this is just a simple tweak in how the display pipeline handles some lines draw order, but I know there are no “quick fixes” or “small issues” when it comes to such complex things as Rhino display. To my layman’s eye it looks like with transparency the edges/curves are drawn not 100% opaque to react to being behind transparent faces, and with Sun+Skylight this opacity factor is reduced way too much.
Another observation, if this is helpful, is that objects that have any transparency in their material, don’t have this problem - their edges are drawn normally through transparent objects even with Sun+Skylight.
So the first question is if you could see the issue on your end, and if so, could this be fixed so there is consistency in Rhino edges display through transparent objects with Sun+Skylight enabled?
thanks!
–jarek
@jeff, here is one more sample showing something being off with Sun+Skylight+Transparency - curves and edges that are non-black actually are getting brighter that original while visible via transparent objects:
Hi @Jarek,
Thank you for the videos and the example model!
I made a YouTrack item: https://mcneel.myjetbrains.com/youtrack/issue/RH-65340.
-David
Hi @DavidEranen and @jeff ,
Here is yet another sample/test with the see-through transparent objects being weird with Sun on in Rendered mode (compared to Shaded mode which over here has no lights on). Please note the materials with any transparency would show edges but the transparency of transparent objects behing other transparent objects is messed up as well all edges seems to go into Xray mode vs gradually diminishing when being behind some transparent faces.
Here is the file used in the video below:
Rhino_Display_Transparency_Problem.3dm (18.4 MB)