How to rotate a point around another one

fromComp

thisComp

toComp

Say you have two lens flares applied to the same layer. Assuming you want to

control the angle of the second flare relative to the first flare with an

Angle Control, you could use an expression like this for the second flare's

center point:

angle = effect("Angle Control")("Angle");

p1 = toComp(effect("Lens Flare")("Flare Center"));

p2 = toComp(value);

delta = p2 - p1;

radius = length(p2,p1);

a = Math.atan2(delta[1],delta[0]);

newAngle = a + degreesToRadians(angle);

x = radius*Math.cos(newAngle);

y = radius*Math.sin(newAngle);

p1 + fromComp()

Dan