• Adobe After Effects Expressions

  need orientation of an object to camera

  Posted by Mike Gottschalk on July 29, 2009 at 4:58 pm

  I had a solid in After Effects and I was trying to get the values of its orientation relative to the world. These values were displayed as Source Text in a text layer above it through the following expression (based on the expression Mr. Ebberts):

  C = thisComp.layer(“solid”);
  u = C.toWorldVec([1,0,0]);
  v = C.toWorldVec([0,1,0]);
  w = 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;
  }

  xValue=Math.round(radiansToDegrees(a));
  yValue=Math.round(radiansToDegrees(b));
  zValue=Math.round(radiansToDegrees(c));

  [(xValue),(yValue),(zValue)]

  Does anyone know of a way to get the values of that solid’s orientation relative to an animating camera?

  Thanks for any help!

  -Mike

  Mike Gottschalk replied 16 years, 9 months ago 2 Members · 2 Replies
• 2 Replies

• 

  Dan Ebberts

  July 29, 2009 at 7:56 pm

  Try this:

  L = thisComp.layer(“solid”);
  C = thisComp.activeCamera;
  u = C.fromWorldVec(L.toWorldVec([1,0,0]));
  v = C.fromWorldVec(L.toWorldVec([0,1,0]));
  w = C.fromWorldVec(L.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;
  }

  xValue=Math.round(radiansToDegrees(a));
  yValue=Math.round(radiansToDegrees(b));
  zValue=Math.round(radiansToDegrees(c));

  [(xValue),(yValue),(zValue)]

  Dan
• 

  Mike Gottschalk

  July 30, 2009 at 12:48 am

  Dan,

  That’s great! Thanks!

  -Mike

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