'rock' frame rate

[iamkaant@…]

From #20432: the framerate of ‘rock’ command isn’t stable, and changes sometimes on window focus change, or seems to be creeping a bit over time, so sometimes rocking seems faster or slower at the same ‘cycle N’

[Tom Goddard]

The rock command renders a specific number of frames each cycle of going back and forth. It does not attempt to make the perceived speed the same. If your graphics rendering slows down then it will appear to rock slower. Also it remembers the center and axis of rotation, so as you move the model (change focus) it may appear to rotate about a different direction (not fixed to the vertical screen axis) and the center of rotation stays fixed with the atomic structure which may be off the screen (ie it does not stay in the center of the screen) if you zoom in on a different part of the structure.

Is what you are observing consistent of this explanation of how rock is supposed to behave?

[iamkaant@…]

Hi Tom,

Thank you for the explanation, that clears up a lot! I experience differences in the perceived rotation speed upon 
stopping and restarting the “rock” command
mid-rotation, when at some range of angles the rotation is faster, and at other angles it’s slower. Basically, the rotation is “choppy” sometimes.

I use ChimeraX on a MacBook Pro with an M5 Pro, and I don’t see substantial changes in CPU or GPU load when it happens. 

It's only a minor inconvenience rather than a real problem, but I’ll be happy to help with debugging.

Sincerely,
Andrii

[Tom Goddard]

Hi Andrii,

Sounds annoying. I don't have an idea what causes this. The rock command rotates faster in the middle of a cycle and slows down smoothly at the ends where it reverses direction. When you say it is choppy do you mean if freezes for a half-second then continues? Such might perhaps happen when ChimeraX checks for new plugins on the web or for updated ChimeraX, but I think that would be very rare.

I have not observed unexplained rock choppiness on my Mac Studio M2 Ultra. I do see when I have a ribbon depiction of a large structure (PDB 3j3q, 3 million atoms) when the mouse is hovered over the rocking model it will pause for half a second to figure out which residue is under the mouse.

Probably the only way for me to understand just what you are seeing is for you to record a screen capture video of the choppy behavior. Mac /Applications/QuickTime Player can record screen videos.

Tom