• Adobe After Effects Expressions

  Rotating the Shortest Way Possible

  Posted by Frankie Jones on December 8, 2022 at 3:14 pm

  Hi,

  How can you ease between 2 values the shortest way possible i.e. ObjA is at 2 degrees and ObjB is at 350degrees, how do you make ObjA rotate 2,10,359,358… etc. rather than 2,3,4,5,6…. The code below weights between 2 values: Value A when Slider is 0, Value B when Slider is 1. Something I can’t figure needs to be added to make it Rotate forwards or backwards depending on which is shortest way:

  // On Rotation
  var total = 0, totalWeight = 0, remWeight = 0;
  var rot  = thisComp.layer("Target").transform.rotation);
  if (hasParent) rot = parent.rotation;
  var fade = effect("Slider Control")("Slider");  // Slider is 0 to 1
  total += fade*rot;
  totalWeight += fade;
  remWeight = 1 - totalWeight;
  totalWeight==0 ? value : linear(remWeight,total/totalWeight,value);</li-code>

  Filip Vandueren replied 3 years, 7 months ago 2 Members · 2 Replies
• 2 Replies

• 

  Filip Vandueren

  December 8, 2022 at 9:21 pm

  The easiest fix is to use Orientation on a 3D layer.
• 

  Filip Vandueren

  December 9, 2022 at 8:58 am

  I couldn’t really deduce what you were doing with the weight variables.

  Here’s an example that bases itself off of the rotation keyframes already present and always takes the shortest route (always <=180°)

  nk = nearestKey(time);
  prevKey = key ( nk.time  >time ? nk.index-1||1 : nk.index );
  nextKey = key( Math.min(numKeys, prevKey.index + 1) );
  delta = (nextKey.value - prevKey.value)%360;
  shortRoute = Math.abs(delta)>180 ? (Math.abs(delta)-360)*Math.sign(delta) : delta;
  // longRoute = Math.abs(delta)<180 ? (Math.abs(delta)-360)*Math.sign(delta) : delta;
  
  linear(time, prevKey.time, nextKey.time, prevKey.value, prevKey.value + shortRoute);

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