Move a "Red Dot" on a path, by only the Dot’s X position?
by Sune Rasmussen
on
May 6, 2008 at 8:49:51 pm
I was explaining a co worker how a special electrical AC motor starts. And I figured a small animation would help.. And it seems to be a quick one.. But now I am stuck..
I have XY graf, with a curve (path). X is Volts, and Y is Amps. And I what a "Red Dot" (shape) crawling along the curve.
Could anyone help me with a expression, so I can control a "red dot", by keyframing only the position[X] value of the "red dot".. and the position[Y] should come from the path…
The reason I am not just keyframing a motion path, I tried, is that the path itself is changing.. and I have a hard time to get it, to look right..
In my mind it should be a easy one, but I can’t find a good solution!!
Re: Move a "Red Dot" on a path, by only the Dot’s X position? by Darby Edelen on May 7, 2008 at 4:15:23 am
This one sounds a little confusing. So to clarify, you have drawn an open mask (path) on a layer that moves (the mask shape is animated) over time?
Man, that sounds like trouble =)
I would say that you should use the Stroke effect and apply an expression to keep the end of the stroke close to the start (subtract 1% from the start value?) and then animate the start position. However, this does not work based on an x-value but rather on the percentage traveled along the path... So unless the path can be mathematically described you may have to fake it with this method.
I'll keep thinking on this though.
Darby Edelen Lead Designer Left Coast Digital Santa Cruz, CA
