I have this graphic in an answer in another SE site:

Source graphic

It has been produced in Inkscape, and I can easily make various parts into separate PNG files (by using layers).

My objective is to make an animated GIF (or movie) where the opacity of the blue line which goes from Tx to Rx moves sideways over a couple of seconds, to indicate the data movement.

Thus, holding the rest of the image unchanged, the blue line (the one with the arrows) might start at 50% opacity, and smoothly turn to 100% opacity, from left to right.

So far I have the blue line in a separate PNG file, and the rest of the image in another one.



The rest:

Rest of graphic

I made a mask, and keyframed its shape so that it gradually covers the area occupied by the area. But now I'm stuck.

I can't put it all together to get the effect I described.

So far I have this in the Video Editing layout:

Video editing


  • The mask affects both images
  • It just makes the image white rather than change its opacity, like this:

Mask result

I've also tried various things in the Compositor without any real success.

Is there a simple and easy way of achieving this?

  • $\begingroup$ This is an extremely late partial answer but you may want to try this in the 3D view, create 2 planes for your two images, add another plane with a mask transparency, change the pivot point to the edge, keyframes the size and etc. $\endgroup$ – Bradman175 Nov 18 '16 at 10:54
  • $\begingroup$ @Bradman175 That's helpful, thanks! I set up a plane with the first image, but am a bit unsure about making a mask transparency that moves sideways. Is there a link to a tutorial for doing that? Is it something you would do in the 3D view, or the Compositor? $\endgroup$ – Nick Gammon Nov 20 '16 at 8:20
  • $\begingroup$ When I have time, I will make a proper answer with some images. $\endgroup$ – Bradman175 Nov 20 '16 at 11:02

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