Weird behavior of scripted controllers in 3ds Max 2011

loocas | 3ds Max,maxscript,technical | Wednesday, March 30th, 2011

I just bumped into a very weird thing.

I have a master object that stores a Custom Attribute definition with some reserved value containers and a function that gets called from withing scripted controllers (float_script()) that calculates a wheel’s circumference based off of the input data (wheel radius, distance traveled etc…).

Now, I’ve noticed there is a constant call to this CA function when I have a graph editor open and simply move my mouse cursor on screen across the viewports! This is pretty bad for the setup I have since it forces the wheels to update their rotation values many times more often through a single frame than it should! I have no idea why this is or how to stop it, but it’s something you should consider when tweaking your rigs!

This happened on 3ds Max 2011 x64, not sure about other versions, though.


  1. There’s no way to stop the scriptcontroller to not update whenever it feels like. The only thing you could do to make sure the values are the same on a particular frame is to build in some check, on the script controller check if the newValue is different then the old value and call the fn on the ca. If it’s the same after that first call, there’s no need to call the ca fn again. Also, this types of setup almost always require baking of animation, especially when throwing the animation to render on the farm.


    Comment by JHN — April 3, 2011 @ 14:17

  2. Hey, JHN,

    thanks for the comment.

    Yeah, I setup the rig for baking, that’s not a problem, but I was really surprised that when I had the Graph Editor open and I only panned in the viewport, that triggered the controllers to update. It slowed down the scene so much I had to disable the controllers if I wanted to animate the rig itself! I then reenabled the script controllers and baked down the keyframes for network rendering.

    Comment by loocas — April 3, 2011 @ 20:58

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