Following a bline

Hello, this is my first post in the forum, and it’s a beginner question (I hope not very annoying). I also want to apologize for my spanglish in advance.

I’m testing diferents features of synfig, and now I’m learning how to make an object follows a bline.

I’ve read the tutorial, and it’s ok, but then I do some changes and it doesn’t work as I expect when the bline is a circle (or the bline is a loop one).

For example, I want to simulate a planet orbiting around the sun. I create a simple circle layer for the planet, and a bigger bline with the circle tool (checking the outline bline option). Then I link the circle layer to the outline bline.

So far, everything is fine, but at this point, I don’t know how to make the animation.

I add a keyframe at 0s, then I add a second one 12 frames later and I change the position of the planet. It works. I add a third keyframe at 1s without problems.

But when I add another one, changing the position of the planet beyond the vertex duck on the bottom of the bline, the planet changes its direction in the animation.

How can I tell synfig what direction the circle layer has to follow?

Planet animation.sifz (1.98 KB)

Okay, here’s one solution for you…

Select your planet, and in the parameters window you’ll find the origin. Expand this and you’ll see a value called “amount”. You can animate this - something like 0,3333 0,66666 0,9999 on each keyframe, so it will go around in a complete circle.

But, you probably want it to go around and around continuously. So right click on the “amount” and convert to “time loop”. Then expand the amount parameter, you’ll see “link”, you can animate this (same as above - keyframe 1 is 0, keyframe 2 is 0.3333 etc). Now make sure animation mode is off again, and change the “duration” of the time loop to 1s12f. You can also change the “local time” to adjust where the planet starts on its orbit.

Hope that helps

Thank you, saorsa.

Now I understand how it works.