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  • Dan Ebberts wonderful expressions

  • Gerald Gutberlet

    April 22, 2020 at 4:30 pm

    Hello I try to combine 2 expressions from Mr Ebberts that found on this forum
    but I am to stupid
    What I want to achieve is that I can control the in point and the duration of a 4 Keyframe Opacity animation

    for the In point I found this nugget

    A = effect(“in Point”)(“Schieberegler”);
    delta = A ;
    valueAtTime(time – A)

    and for the duration in found this nugget

    ip = effect(“Duration”)(“Schieberegler”);
    d = key(numKeys).time – key(numKeys-1).time;
    if (time > (ip – d)){
    t = key(numKeys-1).time + (time – (ip – d));
    t = Math.min(time,key(numKeys-1).time);

    individually they work great but as I said I am to stupid to make them both work
    Please excuse my English its not my first language
    And I want to thank Mr Ebberts for sharing his knowledge I learnt a lot over the years from his forum posts and his old homepage but obviously not enough

  • Dan Ebberts

    April 22, 2020 at 4:51 pm

    Something like this should let you control the start of the keyframe sequence with the In Point slider, and the duration with the Duration slider:

    ip = effect("In Point")("Schieberegler");
    d = effect("Duration")("Schieberegler");
    if (time < ip){
    }else if (time < ip + d){
    t = linear(time-ip,0,d,key(1).time,key(numKeys).time);


  • Gerald Gutberlet

    April 22, 2020 at 5:41 pm

    Thank you of course does it work.
    there is one small thing the opacity animations was meant to switch the layer on and of so I keyframed frame 0 with value 0, frame 1 with value 100, frame 2 with value 100 and frame 3 with value 0 again.
    your expression seems to interpolate this into a dissolve of 25 frames
    but that is okay for me. I will try to figure it out myself.
    Actually I just found out was it was. I had to separate the in and out animation for about 4 seconds and now it just switches the layer on and off just like
    I needed it to be.
    Thank you a lot
    you really helped me.
    have a nice day

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