• Adobe After Effects

  I’m stumped

  Posted by Robert Paynter on January 16, 2008 at 4:59 pm

  What I’m trying to do is track two points of a human in motion.
  Lets, say for example, the hand and the foot. Then create a string between to two. Easy enough with corner pin, stroke, etc., Heres the challenge I would like to add arrows on either end that would follow the angle the line is creating.

  got that ?

  anyone have any advice, answers?

  Darby Edelen replied 18 years, 4 months ago 3 Members · 2 Replies
• 2 Replies

• 

  Steve Roberts

  January 16, 2008 at 6:36 pm

  This is probably an expression thing – try posting in the Expressions COW.
• 

  Darby Edelen

  January 16, 2008 at 7:58 pm

  I would recommend applying the position tracking data of one point to Null A and the position tracking data of the other point to Null B. Then try a Generate > Beam effect between the Null A & Null B. You will need to use an expression to link the start and end points to Null A and Null B’s positions, I recommend this one:

  l = thisComp.layer("Null A");
fromWorld(l.toWorld(l.anchorPoint);

  You will also need to have an expression to rotate the Nulls properly based on their positions, this should work applied to their rotation properties:

  nullA = thisComp.layer("Null A");
nullB = thisComp.layer("Null B");
p1 = fromWorld(nullA.toWorld(nullA.anchorPoint));
p2 = fromWorld(nullB.toWorld(nullB.anchorPoint));
v = p1 - p2;
radiansToDegrees(Math.atan2(v[1], v[0]));

  Then create two arrowheads (Arrow A and Arrow B). Parent Arrow A to Null A and Arrow B to Null B, move them into position and rotate them properly relative to the Nulls and you should be good to go.

  Darby Edelen
  Designer
  Left Coast Digital
  Santa Cruz, CA

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