Line sections on a closed curve become partially invisible after point is deleted

Rhino Rhino for Windows
1

I just installed the update Version 5 SR10 64-bit (5.10.41201.11145, 12/1/2014).
Immediately I noticed a very odd behavior - when I deleted a point on a closed 3 degree curve, the two previously connected line segments (which now become one) became more visible the closer it gets to the remaining points on each end, such that it became just visible enough to see that it connects to each point).
Now when I turned points off, the line segment remained invisible (in Shaded, Wireframe and Ghosted view modes). But when I selected the curve again, visibility returned.

I tried to reproduce the behavior. I undid the actions that led up to the anomaly and retraced my steps; but this time I didn’t have the same problem. But I think I might have clicked on the point and moved it slightly differently before deleting it, so I don’t know if I actually was repeating the exact sequence of operations that led up to the issue that first time.

The curve in question was sitting in front of a.jpg bitmap image that I was tracing. It was on a different layer.
I’m running Win7 Pro with an NVIDIA GeForce GTX670 GPU (driver version 9.18.13.3523), driving 2 different monitors, each with different resolutions

2

Update:
Now I’m noticing the behavior whenever I move a point. Is it possible to revert back to the last Rhino version?

3

Hi Dayoldy- how is the image placed? Is it a BackgroundBitmap, or a PictureFrame? Can you post some of the offending curves with the image in place?

thanks,

-Pascal

4

Thanks so much for your quick response Pascal!

It’s a surface plane / picture frame. But as I investigated to answer your question, I’m sure that I see the problem now. I think it’s just newbie user error.
I’m now seeing in the perspective view that the disappearing line sections have actually been moving on the Z axis and going through and behind the image. But all along I had thought that I had been editing strictly in the Top View, so unless I was unknowingly editing in perspective view (certainly possible), I’m not sure how that Z movement could have happened. Assumptions assumptions…

Also I’m still not quite sure what explains the gradual appearance/disappearance of the line, as I’m pretty sure that I had saved my tracing image as an opaque .jpg format rather than a .png with alpha transparency (and I didn’t assign any transparency to it within Rhino).
I’m thinking that it’s probably just an optical illusion, because my curve’s layer color is orange and I was viewing that against a continuous-tone grayscale image with lots of gradation. The contrast is variable so maybe it merely appeared that way.

Sorry for sending you out on a wild goose chase!