Link a Weightmap to a Null

#1

See the attached image. It’s just a mockup I made in Photoshop to illustrate what I’m trying to accomplish.

I had effect I wanted to achieve yesterday and, even though I had never tried it before, the first solution that came to mind was “wouldn’t it be slick if I could just link a weightmap to a null, then when I animate the null the weighted portion of my geometry will move along with it.”

So I went to do a test. I made a cylinder in modeler, created a weightmap on it running lengthwise, then brought it in to Layout and made a null. That’s pretty much where the test ended because, search as I might, I couldn’t figure out how to link the two.

Any ideas?

Thanks,
Dustin

#2

In theory - open Deform tab of object, then enable nodal displacement, add Vertex Map > Weight Map (double click and pick weight map), add Spot > Spot Info, and Item Info (double click and pick Null), add Tools > Mixer. Then add Spot Info Object Spot to Null World Position and connect to Bg Color input in Mixer. Then connect Weight map output to Opacity, and Spot and Item Info World Position to Fg Color input in Mixer, output Color to input displacement vector… Or something like that… Basically take source vector from one item, second vector and mix together…

#3

Yeah, the image I attached may have been a bit misleading. I don’t care about color or opacity at all. The color in the image is only there to illiustrate that:

  • I have a cylinder

  • The cylinder has a weightmap applied to it

  • I made a null in Layout

  • I want the null to dictate the motion of the weighted portion of the cylinder

  • Dustin

#4

You may try the “sockmonkey” funtion.Totally what you need.

#5

what about making a bone and using the translation of the bone with the weight map assigned? That should work exactly the same, except the bone will move in object space, not world space, and you cannot use motion modifiers, which you could normally use on Nulls. But for keyframed motion only, this would work.

#6

Yes, I understand what you need… Color Mixer node works fine with normal vectors, and there is no other vector specific blending node…

#7

Sorry I thought you misunderstood what I was trying to do. I’ll give your suggestion a shot. Thanks for the tip.

  • Dustin
#8

and you cannot use motion modifiers, which you could normally use on Nulls.

you can use them on bones too

#9

Haven’t tried, but couldn’t he just make/turn on some parenting and stuff on the Bones/Null to make it work with the motion modifiers?

(Edit: oh… sorry, i see it is answered :blush: )

#10

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