[chimerax-users] Crossfade rough transition while making a movie

[Tom Goddard]

Hi Ahmad,

  The movie clip you sent Elaine shows a glitch about when the motion stops and crossfade begins where the vertical scale shrinks about 5% in one frame, while the horizontal scale stays the same.  I see this in QuickTime Player on Mac by single stepping with the arrow keys.  Something is clearly wrong with that, maybe some crossfade bug.  But crossfade works correctly in my tests and Elaine's so I am not able to reproduce your problem.  Elaine and I tested on Mac.  I would need a test case to be able to reproduce the problem.

	Tom


> On Feb 7, 2020, at 1:28 PM, Elaine Meng <meng at cgl.ucsf.edu> wrote:
> 
> Hi Ahmad,
> This appearance of snapping to the position may not be very avoidable, because “view” transitions just take a linear path and it always looks somewhat abrupt (to me anyway) when it reaches the endpoint.  There is currently no option to make it go slower when it is closer to the end.  You could try saving an additional position along the way and using it as an intermediate and then going slower after the intermediate by using more frames per distance, and/or you could try adding a few extra wait frames between when it reaches the endpoint and when it starts the crossfade, for example:
> 
> view pos6 50; wait 100
> crossfade 50; view pos5; wait 50
> (OR: crossfade 50 viewpos5 50; wait 50)
> 
> However, I don’t know if either of those would help much.  When I’m making a movie I usually end up experimenting a lot with numbers of frames in movements and waits, but the sharp endpoints of view transitions are not currently avoidable as I understand it.
> Best,
> Elaine
> 
>> On Feb 7, 2020, at 1:10 PM, Ahmad Khalifa <underoath006 at gmail.com> wrote:
>> 
>> Hi Elaine,
>> 
>> Sorry if my description was vague. With the modification you suggested, I still have the rough transition between pos6 and pos5 but with a slower crossfade into pos5. 
>> 
>> I attached my movie (made with script in the original post) to get a better idea of what I mean. At 0:2, pos6 appears like it snaps in place, then the crossfade into pos5 occurs. 
>> 
>> Is there a way to make the transition smoother? 
>> 
>> Regards.   
>> 
>> On Fri, Feb 7, 2020 at 12:18 PM Elaine Meng <meng at cgl.ucsf.edu> wrote:
>> Hi Ahmad,
>> Not sure I understand what you actually want, but I’ll try to answer anyway…
>> 
>> If you mean you want to see a gradual change in position from pos6 to pos5 then you would need to put a frames number after pos5, for example:
>> 
>> crossfade 50; view pos5 50; wait 50
>> 
>> <http://rbvi.ucsf.edu/chimerax/docs/user/commands/view.html#name>
>> 
>> (Crossfade does not interpolate the movement, you have to do it with the view command.)
>> <http://rbvi.ucsf.edu/chimerax/docs/user/commands/crossfade.html>
>> 
>> Some minor notes on scripts.  You do not need “;” at the end of any line; it is only needed to separate commands that are on the same line as each other, as in the example above.
>> <http://rbvi.ucsf.edu/chimerax/docs/user/commands/usageconventions.html#cxc-files>
>> 
>> I hope this helps,
>> Elaine
>> -----
>> Elaine C. Meng, Ph.D.                       
>> UCSF Chimera(X) team
>> Department of Pharmaceutical Chemistry
>> University of California, San Francisco
>> 
>>> On Feb 6, 2020, at 11:59 PM, Ahmad Khalifa <underoath006 at gmail.com> wrote:
>>> 
>>> I want to crossfade pos6 into pos5, the crossfading itself is smooth, but the below script gives me an abrupt transition at the start of the crossfade (at pos6), how can I fix that?!
>>> 
>>> view pos4
>>> wait 30;
>>> 
>>> movie record supersample 3 size 1920,1080
>>> view pos6 50
>>> wait 50;
>>> crossfade 50; view pos5 
>>> wait 50;
>>> movie encode IJ_movie3.mp4 quality high
>> 
>> <IJ_movie3.mp4>
> 
> 
> _______________________________________________
> ChimeraX-users mailing list
> ChimeraX-users at cgl.ucsf.edu
> Manage subscription:
> http://www.rbvi.ucsf.edu/mailman/listinfo/chimerax-users
>