convert channel expession to value and save it

[mstram]

I am working on an air traffic control simulation.

I have added spare channels for spd and bank, then calculate the turn rate and have that in another spare channel.

For the forward motion, I have tz = $T * ch("spd")

turnRate = (1092.95 * tan(ch("bank1") ) / ch("spd"))

I then have the ry channel = to '$T * ch("turnRate")'.

1) If the bank1 channel goes to 0 (simulating level / no turning flight), the plane's ry channel also goes back to 0. I want the "plane" to maintain the current ry (heading), when bank1=0, otherwise it should be changed by the 'turnRate' channel.

So I need to grab / save the last value of the computed ry as the new ry value .. but I also need to keep the ry field dynamic for further heading/bank changes.

I.e. I need to convert the expression to a "frozen" "snapshot" value.

Do I need to use a CHOP ?

Mike

Edited January 26, 2009 by mstram

[edward]

Short answer is yes. Alternatively, consider using POPs instead of CHOPs.

[old school]

It's so easy to access the previous frame's value in CHOPs and that is with the Feedback CHOP.

See the help for that CHOP. I use it often for what you describe.

There's a part of me that things you should move all the logic in to CHOPs btw.

Attached is a real old yet still valid file with banking bats done entirely in CHOPs for you to reference.

batshover3.hip