[chimerax-users] crossfade warps image when transitioning

[Tom Goddard]

Hi Liz,

  Let's talk about a specific test case.  If I run the following commands  I see atoms slowly fade in over 5 seconds

	open 3gbp
	hide #1
	crossfade 300 ; show #1

>From what you describe, it doesn't fade properly on your computer.  Your description that it looks like the lower left corner is shown makes me suspect you have a particular model of MacBook Pro with retina screen and only Intel graphics where we have reports that saving an image in ChimeraX sometimes only shows the lower left corner of what is shown on the scene.  I just tried the above commands and also a version that made a movie

	movie record ; crossfade 300 ; show #1 ; wait 300 ; movie encode ~/Desktop/test.mp4

on a 2019 iMac with retina display and it all worked as expected.

  So I suspect your problem is a know bug in Apple's graphics driver on your particular laptop.    It is only certain MacBook Pro laptops from a few years ago where we have seen the problem.  Unfortunately only Apple can fix that.  Apple decided a few years back to make its own proprietary graphics library called Metal and so their support of the OpenGL graphics standard which ChimeraX uses and works on Windows, Linux, and Mac is poor.  If you have any other computer you can use, I suggest trying your same steps on that computer -- I suspect it will work.

	Tom


> On May 23, 2019, at 4:35 PM, Liz Kellogg <lizkellogg at gmail.com> wrote:
> 
> Hi all
> 
> OK I have a real problem this time (not a silly problem on my end). I'm trying to make movies in chimerax, and I used to be able to use the crossfade function in Chimera to smoothly interpolate two images to change the scene.
> 
> However, in ChimeraX, when I use the crossfade function it either warps the first image or it somehow interpolates a zoomed in view of the lower left corner of the first image into the second, which makes for a jarring transition.  Closing and re-opening ChimeraX seems to change the behavior, but I still can't get a smooth transition between image 1 and image 2. Any idea how to fix this? I thought perhaps setting the view size before starting to record the movie would help, but that doesn't seem to work.
> 
> Thanks a bunch.
> 
> Best
> Liz
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