How can you stop an expression linked to keyframes?

[Dan Ebberts]

Like this:

stopTime = 2;
t = Math.min(stopTime,time);
thisComp.layer(“Layer 1”).transform.position.valueAtTime(t)

Or, you could do it with a marker, like this:

stopTime = marker.key(1).time;
t = Math.min(stopTime,time);
thisComp.layer(“Layer 1”).transform.position.valueAtTime(t)

Dan

[Mike Clasby]

Here’s a nifty Dan expression for starting and stopping an expression at a given frame:

startFrame = 0;
stopFrame = 241;

if (time >= framesToTime(startFrame) && time < framesToTime(stopFrame)){ //your expression goes here }else{ value } Set startFrame and endFrame as needed.

[Mike Clasby]

Ooops, didn’t see you Dan. It takes me longer to look stuff up. Oh, well, more options are good, I guess.

[Daniel Haskett]

Hey Dan,

Thanks for your help, sorry Im still gradually getting to grips with expressions. i tried to use what you said and this is what the expression looks like —

stopTime = marker.key(1).time;
t = Math.min(stopTime,time);
thisComp.layer(“ski dust.psd”).transform.position.valueAtTime(t);
temp = thisComp.layer(“SKIER FINAL”).transform.position;
[temp[0], temp[1]+effect(“Slider Control”)(“Slider”)]

it doesnt seem to work, im sure ive done something wrong. the layer ski dust.psd has its brush position linked to the position keyframes of SKIER FINAL…ive set a marker but still nothing.

any help would be greatly appreciated!

thanks

dan

[Dan Ebberts]

I guess I don’t understand what you’re trying to do. If you applied this expression:

stopTime = marker.key(1).time;
t = Math.min(stopTime,time);
thisComp.layer(“SKIER FINAL”).transform.position.valueAtTime(t);

to the brush positiion and create the marker on the layer with the write-on effect, it should do what I thought you wanted.

I’m not sure what you’re doing with this piece:

temp = thisComp.layer(“SKIER FINAL”).transform.position;
[temp[0], temp[1]+effect(“Slider Control”)(“Slider”)]

Dan

[Daniel Haskett]

hi dan

yeh that works better, the second section was so that i could change the x and y co ordinates – i was using a slider control for y….is there anyway this could be incorporated into the expression?

cheers

dan

[Dan Ebberts]

If you want to be able to offset the write-on effect in the y direction with a slider, you could do it like this:

stopTime = marker.key(1).time;
t = Math.min(stopTime,time);
s = effect(“Slider Control”)(“Slider”);
thisComp.layer(“SKIER FINAL”).transform.position.valueAtTime(t) + [0,s];

Dan