• Adobe After Effects Expressions

  Derive hidden corner pin point from other three

  Posted by Chris Lorance on February 23, 2016 at 4:10 pm

  I’m wondering if there is a way to calculate where one corner of the corner pin effect should be based off the position of the other three (given an initial starting point). I have a screen replacement where three of the points are visible, and can track individually and bind to nulls. However the fourth remains off screen. Might anyone be aware of a solution? I would try the parallel corner pin tracker, but it wont allow me to pull the fourth point off-canvas.

  Xavier Gomez replied 10 years, 6 months ago 2 Members · 1 Reply
• 1 Reply

• 

  Xavier Gomez

  February 25, 2016 at 5:57 pm

  If things are simple enough (that is: if the screen rectangle still appears as a parallelogram), you can use this for the Lower Right corner:

  A = effect("Corner Pin")("Upper Left");
B = effect("Corner Pin")("Upper Right");
C = effect("Corner Pin")("Lower Left");
B+C-A;

  (Similar expressions for other cases, eg Upper Left msssing, etc : permute names).

  Xavier

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