How to rotate a point around another one

[luizfonteboa]

I need to rotate a point reference in a effect

around another point (that is another effect point reference)

keep the second one fixed and make a perfect cicle path.

In other words:

i have an effect applied to a layer

this effect has an reference point

how to rotate around another reference point?

thanks for help

[Dan Ebberts]

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

[luizfonteboa]

thank for your time, Dan.

wouldnt it be a way to link each (effect) center point to a dummy

and rotate each dummy around the other anchor point?

[Dan Ebberts]

Sure. In that case you would attach each effect point like this:

fromComp(thisComp.layer("Null 1").toComp([0,0,0]))

Dan

[luizfonteboa]

To a expressions novice like me,

your first expression was certainly a stuff to keep and study to learn.

But i have to thank you for the second tip: very precious to me - be sure - and useful for many things here.

I think i cant live no more without fromComp.

[luizfonteboa]

fromComp

thisComp

toComp