Connecting movements inside of a mask to a slider

[Kamiar Babaei]

UP

[Dan Ebberts]

You could set up an expression for your mask path, where the height is based on the slider value. This example is more complicated than it needs to be, because I wasn’t sure whether your path goes clockwise or counter-clockwise so the expression allows for either:

s = effect("Slider Control")("Slider");
p = thisProperty.points();
if (p[1][0] < p[3][0]){
  p0 = p[3] - [0,s];
  p1 = p[2] - [0,s];
  newP = [p0,p1,p[2],p[3]];
}else{
  p0 = p[1] - [0,s];
  p3 = p[2] - [0,s];
  newP = [p0,p[1],p[2],p3];
}
createPath(newP,[],[],true)

[Kamiar Babaei]

Thank you so much for this awesome expression.

But what i meant was the white bar inside of the mask is going to move vertically and i need the slider to acknowledge it and set a value to it between 0-100 based of the size of the mask.

is it possible?

thank you so much and sorry for not explaining properly what i wanted at first, i didn’t how to say it.

[Dan Ebberts]

The only thing I can think of would be to use sampleImage() (with postEffect=true) in a loop, starting at the top of the range and moving down (1 pixel at a time) until you find a pixel with non-zero alpha to determine the current height of that bar. Then use that value to drive the height of the mask.