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Activity Forums Adobe After Effects Expressions Replacing actuall position values using clamp?

  • Replacing actuall position values using clamp?

    Posted by Jeff Schreuders on January 24, 2017 at 10:16 am

    Hi there,

    I’m trying to build an on-screen slider within a composition to control something from within the comp itself, instead of using an expression slider in the effect controls window.

    I’ve made a scroll-able object that functions as a slider and restricted the min/max position of the object using clamp. When reaching the min or max value the (red) value of the position, as expected, shows the correct values from clamp. But when I click on the value I noticed that it can actually be higher or lower than the given restrictions of clamp. The problem occurs when the object is dragged past the clamp min/max, the red value shows the min/max value while the actual values just keep going up. When you try dragging the object again this will result in a delay.

    I uploaded a screen capture to clarify the problem:
    https://www.youtube.com/watch?v=LClUKG8JY0w

    Is there a way for clamp to have absolute control of a value to avoid this problem?

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    Emre Anil replied 9 years, 3 months ago 2 Members · 3 Replies
  • 3 Replies
  • Emre Anil

    January 25, 2017 at 6:50 am

    Actually that is not a problem, it’s how expressions work..

    When you set a value with expression you don’t actually change the value, you kinda enhance it with functions etc. but the actual value is always there and you can still mess with it. When you click to a value you see the actual one, not the one effected by the expression..

    when you disable the expression or delete it completely, the property is set to the actual value behind the expression.

  • Jeff Schreuders

    January 25, 2017 at 9:52 am

    Hi Emre, thanks for your fast reply and explanation.
    Is it possible than to change the actual value with expressions?

  • Emre Anil

    January 25, 2017 at 10:09 am

    Unfortunately no..

    Because when you add an expression you create a second value for the property. As soon as you delete or disable the expression the property returns to it’s own value (which you could have changed while the expression was still active as I explained)

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