Elliptical Motion path conundrum

[Kyle Hamrick]

Just off the top of my head:

Couldn’t tell for sure whether you’re going for a circle or an ellipse. If it’s a circle, what if, instead of the motion path, you set these all to be parented to a single null? Make the null at the center of your circle, attach text, offset anchor point… voila. Repeat at appropriate intervals. You can then set up a simple rotation expression to keep the items level while they rotate around.

Let me know if you’d like more details on how to do any of this, if it works for your particular idea….

Kyle Hamrick

Editor/Motion Graphics Artist

http://www.kylehamrick.com

[Tristan Nieto]

Thanks Kyle,

Good thinking, but sadly it doesn’t get around the problem. Just as with the motion path, if the text lines are separated by radians (or degrees) from a centrepoint, they still will collide at the bottom and top.

The problem is basically that one “unit” (whatever you want to measure by) around the edge of a circle will always equate to something different in x/y co-ordinates, depending on where you are. Points at the bottom and top of the circle will tend towards high values for x and low values for y, whilst at the sides this will reverse; lower x values and higher y values. In other words, as you move around the edge of a circle, your x velocity is quite low at the sides, (because you’re mostly moving up and down) and high at the top (because you’re mostly moving side to side).

If all that’s too mathsy for people, just copy a circle mask to an object’s position, then hit the button that separates the x and y keyframes, and have a look at the speed and value curves. Even though the object moves the same distance around the circle every frame, the x and y graphs give you something else entirely. What I’m looking for is a way to have a circle shaped path with the Y speed graph being totally flat.

And if all this sounds terribly confusing, join the club 😉

[Kyle Hamrick]

Aha. Yeah, that makes sense.

…any way you can get fewer of them onscreen at once? 2 or 3 seems a lot more doable, spacing-wise. Maybe you can cheat the movement at the bottom and top to be faster, so you can get them out of each other’s way a little easier?

Maybe you can position them on the circle, but animate them on/off in a different way, aside from having them revolve around it?

Obviously, without seeing your actual example, it’s hard to offer anything too specific. Just throwing out suggestions.

Kyle Hamrick

Editor/Motion Graphics Artist

http://www.kylehamrick.com

[Roland R. kahlenberg]

[Tristan Nieto] “And if all this sounds terribly confusing, join the club ;-)”

I am confused. Howzabout a QT?

RoRK

broadcastGEMs – AEPro Volume 02 (Professional Adobe After Effects Project Files – Now Available).

Adobe After Effects Training in South East Asia.

[David Bogie]

I’m confused too. You lost me with “mathsy.”
I deal with all velocity issues by using a null and parenting the items I need to move to the null. And for almost all text issues that require precise timing, I set each item up as a separate layer.

bogiesan

[Matthew Woods]

I might try parenting your lines to a a null which you animate along the y access at a constant rate. This gives you your constant vertical scrolling. I’d then turn off all lines but one, and animate its position along the x axis placing keyframes at the top and bottom of your curve as it scrolls up the y, and one at the apex of the curve that you set to “rove across time”. I’d then adjust the easing/speed of the first and last keyframes so that your one line follows the curve. Once the one line looks good, I’d copy and paste those keyframes to your other lines and offset them so that they all repeat the same movement.

Am I making sense?

-Matt

[Dan Ebberts]

I’m not sure if this is exactly what you’re looking for, but this position expression should give you a constant y velocity for a path with 2 or more keyframes:

n = thisProperty.numKeys;

if (n > 1){
t0 = thisProperty.key(1).time;
t1 = thisProperty.key(n).time;
v0 = thisProperty.key(1).value[1];
v1 = thisProperty.key(n).value[1];
y = linear(time,t0,t1,v0,v1);
[value[0],y]
}else{
value
}