Re: Some trig help needed

I *think* I've done it (well, it's good enough, at least). Expression for the rotation:


wo = effect("WheelOffset")("Angle"); // arbitrary angle control for fine tuning
Cxy = thisComp.layer("Tandem").effect("RearWheelContactPoint")("Point"); // C in the diagram
Axy = transform.position; // hinge point: A
Bxy = effect("WheelPoint")("Point"); // Rear wheel contact point: B
Dxy = thisComp.layer("TrailerWheelGuide").transform.position; // trailer wheel guide: D

c = length(Axy, Bxy);

theta = Math.atan2(Dxy[1]-Cxy[1], Dxy[0]-Cxy[0]);

sintheta = Math.sin(theta);
costheta = Math.cos(theta);
xs = Axy[0] - Cxy[0];
ys = Axy[1] - Cxy[1];

alpha = Math.asin(((sintheta * xs) - (costheta * ys)) / c) + theta;

radiansToDegrees( alpha ) + wo;


Now to figure out why the guy's shins are coming out of his shoes whenever I move the bike around....