Use A Null Slider To Interpolate Between Series Of Positions

[Christian Geijer]

This maybe isn’t exactly what you want but it might help you on your way.

One way could be to create a .json-file with all the different positions mapped to the corresponding slider value like this:
{
"positions": {
"1": {
"x": 2,
"y": 54
},
"2": {
"x": -4,
"y": -174
}
}
}

Place the .json-file (here named data.json) in your composition and then, with the value from Master slider (in my example placed on a null layer named “Control”), change the position of the object you want to move around with an expression that looks something like this:
id = thisComp.layer("Control").effect("Master slider")("Slider").toString;
x = thisComp.layer("data.json").source.sourceData.positions[id].x;
y = thisComp.layer("data.json").source.sourceData.positions[id].y;
[x,y]


This, however, only works with the slider being set to whole numbers that you also have defined in data.json and does not work if the slider animates between the different values. You maybe can define the first and second positions and use linear() to animate between them, but I’m not sure how you’d want that to work in your specific case.

[Kalleheikki Kannisto]

Basically the same matter as discussed here. No ready expressions, but the basic methodology is there.

https://forums.creativecow.net/thread/227/41791

If the transition time is always the same — which it would have to be if you use just a single slider — you can simplify this by looping back from the current frame for the number frames that cover the transition and checking if the hold keyframe value has changed during that time. If it has, you can calculate the progress between the two positions (read from an array) from how many frames back the value changed (in relation to the full transition time).

Kalleheikki Kannisto
Senior Graphic Designer

[Kalleheikki Kannisto]

For the simpler implementation with fixed transition time and one slider (using hold keyframes), slider on layer “controls”.

Position expression:

pos_array = [[2, 54],[-4, -174],[0, -12],[8, 190]]; // predefined positions array
tt = 10; //transition time in frames
cv = thisComp.layer("controls").effect("Slider Control")("Slider").value; //current slider value
tp = 0; // transition progress default
for (i=0; i

Kalleheikki Kannisto
Senior Graphic Designer