Is it possible to allow continuous sampling of constraint CHOPs? As in, always cook at current time sample, the way a vop using @Time/@Frame, would? I found CHOP constraints are not usable for animation with motion blur, (without changing the sample rate to something like 9600, or some other value approaching continuous), because the sample rate is discrete. Switching from single sample to a frame range allows for interpolation between samples at least, but is much less interactive as the entire sequence must be cached after any change. The old object constraints seemed to operate on cook, allowing for non-discrete sampling.

Hi jsmack,

just had a play with that and yes the only way I could find to get similar results on constrained geo to keyframed geo was to up the samples on the object offset CHOP (I was using a simple parent contraint).

There is something strange going on though, logic would seem suggest that as long as you sample at a rate equal to FPS * ‘Xform Time Samples’ you should get the same results as the keyframed geometry, but this is also not the case…

Cheers,
Henry

Today's 16.0 build has a big change to improve the rate problem.
When you create a constraint, a chopnet_rate parmeter is added to the parent CHOPnet and an expression is hooked up so that the rate is shared by all the child nodes. New nodes in this chopnet will also get a the same expression applied.
I also added a new global variable CHOPMOTIONSAMPLES that you can control globally like $FPS and it's part of the exprssion that is installed.
It still isn't perfect because you'll still get discrete sampling corresponding to the rate, but change the rate in Current frame mode doesn't add the same overheade as in Animation range mode.
You also need to take the camera shutter time into account when you determine the CHOP motion samples.. because it is a multiplier on top of the rate. With the default 0.5 shutter time, you need to multiply the rate by 2.

Thanks Guillaume!

because the it is amultiplier

What does this mean?

I fixed my typos in the original text. In 17.0 and late, I think you don't have to worry about the rate anymore if the CHOP is in current frame mode. It is now able to evaluate at times that aren't matching exactly the sample times.