• Adobe After Effects Expressions

  Expression for Single Keyframe linked to Point Control

  Posted by Max Williamson on March 19, 2019 at 10:59 pm

  Hey There!

  Hoping someone can help me with the following problem. I am templating a fairly complex animation for a team of editors and was hoping to create a user-friendly template. What I am trying to do is link the position (x,y) of two keyframes to a Point Control without adjusting the other keyframes on the layer. Is this possible with an expression?

  The idea is to quickly reframe a video layer within a frame while maintaining the position of the first and last keyframes.

  Thank you to anyone who can help!

  M

  Max Williamson replied 7 years, 5 months ago 2 Members · 2 Replies
• 2 Replies

• 

  Andrei Popa

  March 20, 2019 at 6:54 am

  I assume your mid 2 keyframes are equal. If you use normal ease or no ease, you can do this:

  pointControl = thisLayer("Effects")("Point Control")("Point");
time1 = key(1).time;
time2 = key(2).time;
time3 = key(3).time;
time4 = key(4).time;

  if (time < time1) {
value;
} else if (time < key(2).time) {
ease(time, time1, time2, valueAtTime(time1), pointControl);
} else if (time < time3) {
pointControl;
} else if (time < time4) {
ease(time, time3, time4, pointControl, valueAtTime(time4));
} else value;

  If you use no ease, just replace ease with linear. If you need further clarification and/or help, don’t hesitate to ask.

  Andrei
  My Envato portfolio.
• 

  Max Williamson

  March 20, 2019 at 11:35 pm

  Sorry I may have spoken too soon. With the ease and wizz expression, how do I tie this in?

  function easeandwizz_inoutExpo(t, b, c, d) {
  var CORRECTION = .000976563;
  var v;
  if ((t/=d/2) < 1) {
  v = Math.pow(2, 10 * (t – 1)) – CORRECTION;
  } else {
  v = (-Math.pow(2, -10 * (t – 1)) + 2) + CORRECTION;
  }
  return b + (v/2) * c;
  }

  function easeAndWizz() {
  var n = 0;
  if (numKeys > 0) {
  n = nearestKey(time).index;
  if (key(n).time > time) { n– }
  }

  try {
  var key1 = key(n);
  var key2 = key(n+1);
  } catch(e) {
  return null;
  }

  // determine how many dimensions the keyframes need
  var dim = 1; // It’s gotta have at least ONE dimension
  try {
  key(1)[1];
  dim = 2;
  key(1)[2];
  dim = 3;
  } catch(e) {}

  t = time – key1.time;
  d = key2.time – key1.time;

  sX = key1[0];
  eX = key2[0] – key1[0];

  if (dim >= 2) {
  sY = key1[1];
  eY = key2[1] – key1[1];

  if (dim >= 3) {
  sZ = key1[2];
  eZ = key2[2] – key1[2];
  }
  }

  if ((time < key1.time) || (time > key2.time)) {
  return value;
  } else {
  val1 = easeandwizz_inoutExpo(t, sX, eX, d);
  switch (dim) {
  case 1:
  return val1;
  break;
  case 2:
  val2 = easeandwizz_inoutExpo(t, sY, eY, d);
  return [val1, val2];
  break;
  case 3:
  val2 = easeandwizz_inoutExpo(t, sY, eY, d);
  val3 = easeandwizz_inoutExpo(t, sZ, eZ, d);
  return [val1, val2, val3];
  break;
  default:
  return null;
  }
  }
  }

  (easeAndWizz() || value);

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