Hi All,
I am trying to get the flapping speed of a wing to drive the $TY position of a point , ie the faster the wing flaps the greater the climb in positive $TY and likewise the slower the wing flaps the $TY will fall in a negative manner. I might be totally going in the wrong direction with my thinking that this would be the right way to go so any input would be very welcome.

I figure if the sin () value goes above a certain level the $ TY expression would be true and if the sin() value then falls below a certain value the $TY value would be false

Regards R

This is a pretty straitforeward task with CHOPs. You can count the revolutions and recursivly sum them if necessary with the oc() expression in the expression CHOP. You can then normalize the curve, and use this to multiply or manipulate an animation of TY

Let me know if you'd like a simple example of what your talking about.

Here's a scene where the speed of the characters is driven by the up or down velocity, with rate, of the train cart.

Alternatively, and since you talk about TY as having a direct linear relationship to frequency, then TY is nothing more than some multiple of the frequency:

RZ = sin($T*360*FLAP_FREQ)*FLAP_AMP
TY = LIFT * FLAP_FREQ

Where LIFT is the scaling factor that relates the vertical position to the flapping frequency, and FLAP_FREQ and FLAP_AMP are the frequency (in cycles per second) and the amplitude (in degrees) of the rotation that creates the flapping, respectively.

Mind you, if this is intended for a bird's motion, it's not going to look very realistic at all, I'm afraid. For that you'd need to at least bring in gravity and express lift as an acceleration (CHOPs).

Acually if there is a crowd of birds it's probably best to do this by summing point attributes in a particle definition in vops. The math can be worked out in CHOPs ahead of time though since it's visual

Thanks so much guys for the answers , yes this is for bunch of birds ….
Andrew a simple scene fiel would be great ! In the meantime I will be looking at the one you have posted

R

this is for bunch of birds

If it is a bunch of birds, I'd rather simulate the birds and control their wing flapping depending on their behavior.

Btw: here is a nice flock of birds:
http://www.flight404.com/blog/?p=99 [flight404.com]

Georg