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Making the opacity to switch on and off - should be easy.

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Thor Hansvik
Making the opacity to switch on and off - should be easy.
on Jan 19, 2013 at 9:56:22 am

Yes, I am new to this...

I have a precomp I want to switch the opacity to 0 and 100 for every e.g. 10th frame. That is, 0% for the 10 first frames, then 100% for the next 10 frames and back to 0% for the next 10 frames and so on...

I tried the following expression but I guess that the state variable is initialized for every new frame. Thus, the opacity stays at 100% for 10 frames, switching to 0% for one frame, and then switching back to 100% for the next 10 frames and so on.

How (if possible) do I prevent the state variable to be initialized for every new frame, or solve this problem?


frames = timeToFrames() % 10;
state = 1;

if (frames == 0)
state = state * -1;

if (state == 1)
f = 1;
else
f = 0;

transform.opacity = 100*f;


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Dan Ebberts
Re: Making the opacity to switch on and off - should be easy.
on Jan 19, 2013 at 5:37:55 pm

This should work:

f = timeToFrames(time-inPoint);
Math.floor(f/10)%2 ? 100 : 0



Dan



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Thor Hansvik
Re: Making the opacity to switch on and off - should be easy.
on Jan 20, 2013 at 11:31:11 am

Thanks, it works!

Do I understand this right; The intire expression code is executed for each frame? Is it possible to define a variable that is initialized at "start up" (frame 0 or -1) ?


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Dan Ebberts
Re: Making the opacity to switch on and off - should be easy.
on Jan 20, 2013 at 5:18:02 pm

>The intire expression code is executed for each frame?

Yes.

> Is it possible to define a variable that is initialized at "start up" (frame 0 or -1) ?

No, variables can't persist between frames.

Dan



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