• Adobe After Effects

  Concentric circles followup — need expression to position logo in center

  Posted by Shaun Kurian on January 8, 2007 at 2:23 pm

  This is what I have so far:

  I have arranged 24 frames around each circle using position and rotation expressions.
  I have 10 of these circles with the radius increasing by a variable of 200 with
  each circle, i.e. the first circle has a radius of 600, the 2nd circle has a radius
  of 800, the third circle has a radius of 1000, etc until the 10th circle which has
  a radius of 2400.

  This is what I need:

  I need to center a 3d logo (made with invigorator) at the center of these circles.
  I imagine that the radius for this logo could be 400. What expression could I use
  for the logo such that no matter how I move the camera around the circles, the logo
  stays in the center of the whole thing?

  Mylenium replied 19 years, 7 months ago 2 Members · 1 Reply
• 1 Reply

• 

  Mylenium

  January 8, 2007 at 7:36 pm

  [Shaun] ”
  I need to center a 3d logo (made with invigorator) at the center of these circles.
  I imagine that the radius for this logo could be 400. What expression could I use
  for the logo such that no matter how I move the camera around the circles, the logo
  stays in the center of the whole thing?”

  Do it the other way around: Tie your circles to the logo.

  center=thisComp.layer(“Logo”).position; //position of the logo
  radius=200; //one circle
  angle=degreesToRadians(360/24); //circle segments

  X=center[0]+Math.sin(angle*index)*radius;
  Y=0;
  Z=center[2]+Math.cos(angle*index)*radius;

  [X,Y,Z]

  I don’t use Invigorator, but I know that it can be made to use a reference object, so your “Logo” in the above code should be this treference object. To permanently orient it towards camera, use eitehr auto-orinet or this code on the orientation property:

  lookAt(position,thisComp.layer(“Camera”).position)

  Mylenium

  [Pour Myl

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