The "Convert" menu allows you to specify that the parameter should be controlled automatically in various ways. Ok, but once the parameter is converted to the other(s) one(s), how can it be automatically controlled? Maybe the parameter is now controlled by waypoints and keyframes as the normal parameters?. I'm interested into this feature because I have found that some layers (Eg. Curve Gradient) donesn't work properly in the version I have of synfigstudio (Vertices are "Unknown type". I hope using "convert" can arrange it and use some types of layers that seems that the default values are incorrectly set. Bye, Genete.
What version to do use? When you convert the parameter, all existing waypoints for that parameter are deleted (I think) and you won't be allowed to edit that parameter directly any more. Instead, you edit the new sub-parameters.
Suppose you have a circle. Right-click its radius and convert to linear. Switch to animate-edit-mode, set the default interpolation type to be Constant (that's the very bottom setting in the toolbox window) and at time zero, set the rate to be 0.5 and the offset to be 0.5. That means the radius starts at 0.5 units and grows by 0.5 every second. You might have your parameters to be displayed in 'points' or some other unit. You can change that from the toolbox using File>Setup>Misc>Unit System. Set that to Units for this example. Don't forget to set it back after if you want to work in points again.
You'll see that there are now waypoints on the 'offset' and 'rate' parameters, and you can animate those parameters just like you could animate the radius before.
Go forward to 1s in the animation. You'll see that the circle's radius is now 1 (it grew by 0.5u from 0.5u), and set the rate to -0.5 and the offset to 1.5. This will cause the circle's radius to start shrinking by 0.5 per second from the 1s point onwards. The 1.5 offset is to arrange that the radius doesn't jump suddenly at 1s. If the radius is to go down from 1.0 at 1s at 0.5 per second, it would have been at 1.5 at 0s, so that's the offset we use.
Does that make sense? -- dooglus