• Adobe After Effects Expressions

  toWorldVec – global orientation fails when above 90 degrees

  Posted by Simon Bjork on January 3, 2021 at 12:36 pm

  I’m having some trouble with extracting the global orientation values using the toWorldVec method.

  It all seems to work well as long as the rotation values are within -90 and 90, but outside of that it fails. Example:

  – Create a new camera and animate the Y rotation from 0 – 150 degrees.

  – Create a text layer and apply the following expression to the sourceText property (Dan Ebberts):

  C = thisComp.layer("Camera 1");
  u = normalize(C.toWorldVec([1,0,0]));
  v = normalize(C.toWorldVec([0,1,0]));
  w = normalize(C.toWorldVec([0,0,1]));
  
  sinb = clamp(w[0],-1,1);
  b = Math.asin(sinb);
  cosb = Math.cos(b);
  if (Math.abs(cosb) > .0005){
  c = -Math.atan2(v[0],u[0]);
  a = -Math.atan2(w[1],w[2]);
  }else{
  a = Math.atan2(u[1],v[1]);
  c = 0;
  }
  s1 = "3x3 Matrix: \n" + u + "\n" + v + "\n" + w
  s2 = "Rotations:\n" + radiansToDegrees(a) + "  " + radiansToDegrees(b) + "  " + radiansToDegrees(c)
  
  s1 + "\n\n\n" + s2

  <div>As soon as the rotation gets above 90, everything breaks. The X rotation and Z rotations change from 0 to -180 and 180 and the Y rotation starts to move in the opposite direction.
  </div><div>

  Any suggestions how to fix this? If possible I’d like to edit the matrix (toWorldVec) as I’m not using this particular matrix > euler conversion. But I’m open to any suggestions.

  Thanks,

  Simon

  </div>

  Simon Bjork replied 5 years, 8 months ago 1 Member · 0 Replies
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