Calculating angle from two points

[Navarro Parker]

As everyone knows, using the ol’ Gradient Ramp effect gives you two point controls for the start and end of your ramp.

I need to use a different gradient effect that only has one point control and an angle control.

What would be an expression to derive an angle value based on the two point controls?

[Kevin Camp]

Math.atan2(y,x) is the function that you are looking for.

to get an angle from the ramp effect’s start and end points, try this:
L = thisComp.layer("Layer with Ramp Effect");
p1 = L.effect("Gradient Ramp")("Start of Ramp");
p2 = L.effect("Gradient Ramp")("End of Ramp");
p = p2 - p1;
radiansToDegrees( Math.atan2( p[1], p[0] ) );

depending on where you want zero degrees to start, you may need to add or subtract 90 degrees (currently zero is pointing right)

Kevin Camp
Art Director
KCPQ, KZJO & KRCW