simple animation that I can't do

Hi everyone,

I was looking for a way to do short little animations for presentations, and heard about synfig…
I followed a few tutorials so far to get to know the soft better, thanks to them I could realize most of the animations I need, however I still can’t figure how to make this simple animation :

Would any of you know a way to draw a long rectangle, then animate it so that it becomes a circle (like making it wrap around a circle, or bending the 2 extremities to make them joining…) ?

I tried to replicate this effect using the curve warp tool, but I couldn’t get a smooth circle as ending configuration…

Thanks for your help,

Hi synister-noob,
Something like this?
rectangle-circle.sifz (3.3 KB)
How I did it:

  1. With the Circle Tool select create Outline. Select the number of points to be 4 and angle to be zero.
  2. Make one circle at the desired size. Increase the width to the final value (60 pixels or whatever)
  3. Make the outline end and start tips to be not rounded.
  4. Near the bottom vertex, right click the bline and select ‘Insert Item Smart’.
  5. Right click the circle bline and select ‘Unloop’. It will open the bline between the new inserted and the bottom vertex. If that doesn’t happen then right click and Rotate Order until that happen. Adjust the vertexes to make them coincide in position and tangent at the bottom.
  6. Add one keyframe and animation start and other at animation end.
  7. Change to animation mode and be sure lock future keyframes is on.
  8. At start keyframe, un bend the bline and convert it to a rectangle. Use the grid and snap to grid.
  9. Add as many intermediate waypoints as you want to make bending animation smooth.

I hope it helped.

oh, this looks good, thanks for this fast reply (I was redoing the effect using math formulas (the rectangle being like a small arc on a huge circle, with the circle getting smaller and smaller lol), and while this gave a very smooth animation I think it will be easier to use your solution to integrate with my other animations and to draw stuff inside the rectangle :slight_smile: )

I’m gonna experiment a bit with your solution, thank you very much for the detailed explanations :smiley: