after-effects

calculate the angle between two points in after effects

I am trying to create an arrow with a line in after effects. The start point is always static, the end point can be moved with sliders and on the end point there is a triangle pointing in the direction the line is pointing.

The line itself is no problem: I used the pen tool to create a path, used create nulls from path and added sliders to the null that controls the end point.

The triangle part is what I can't seem to figure out. On the rotation property of the function:

var p1 = thisComp.layer("Start").transform.position;
var p2 = thisComp.layer("End").transform.position;
radiansToDegrees(Math.atan2(p1,p2);

(Start and End are the Nulls controlling the path)

I assume atan2 is the proper approach in this scenario but Ae gives me an error and the result of the final line is NaN. Any help is much appreciated.

Solution

  • Late answer but try this:

    p1 = thisComp.layer("Start").transform.position;
p2 = thisComp.layer("End").transform.position;

v = p2 - p1;

radiansToDegrees(Math.atan2(v[1], v[0]));

    In your code there is a close parenthesis missing at the end, that's why the error.