CGTalk - Animateable Belt/Strap Ideas??

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MidnightCow

07-03-2008, 03:35 PM

I`m creating an animation involving a harness (basically like a car seat-belt) and looking for a quick way to create/animate it..

I`ve experimented with sweep-nurbs but even using a rail spline it`s very difficult to control the rotation of the belt - for example where it attaches to the clip needs to be accurate..

Currently messing with xpresso to try and use helper-boxes to control the graph rotation-points of the Sweep-Nurbs - but on the other hand thinking theres usually a simpler way..

Any ideas folks?

RandyLeeBlain

07-03-2008, 04:03 PM

Convert to polys and use deformers or joints to deform accordingly. You will have more control. For example, LoftNURBS will not rotate its sections in a full circle like SweepNurbs without collapsing flat.

HTH
Randy

LemonNado

07-03-2008, 04:22 PM

sorry... wrong post...

LucentDreams

07-03-2008, 05:32 PM

Spline IK controlling the spline and then sweeping the shape along that spline. this way nulls can control position and rotation of points as well as length of tangents without ever needing to go into point mode.

MidnightCow

07-03-2008, 08:25 PM

Thanks guys:

Randy - I thought maybe the spline rail deformer but again it`s difficult to keep the shape consistent and have easy rotation control (similar to the sweep-nurbs)..

Lucent - How can nulls control tangent lengths? Also, i`m not sure whether the rotation of spline points makes any difference to the sweep-nurbs rotation..

Going to mess around some more but i guess there`s no simple way, definately going to have to rig it with xpresso + null objects but the only way to do that is by affecting the sweep-nurbs `rotation` graph, which will be tricky to get right..

Horganovski

07-03-2008, 08:38 PM

How do you make the spline IK affect the rotation of a spline point?
With the default settings the handles only seem to rotate the joints themselves.

Cheers,
Brian

MidnightCow

07-03-2008, 09:19 PM

Ok here`s what i have so far using Lucents method of SplineIK for the sweep-shape.. Problem is the sweep-nurbs doesn`t respond to points rotation on i think the `y` axis, and as u can see in the video x rotation is not accurate (visually anyway)..

Sorry for the poor vid quality first time i tried camtasia:

DivShare File - camtest.avi (http://www.divshare.com/download/4862503-5ad)

- Can`t i embed video on here?

MidnightCow

07-03-2008, 11:27 PM

Here`s the best i can come up with (C4D 10.5 file attached).

It`s a combination of sweep-nurbs, with 2 rail-splines (both with splineIK), and the individual pairs of IK Handles grouped into nulls that can be manipulated easily..

Has some flaws but on the surface of it works relatively well.

Horganovski

07-04-2008, 04:56 PM

Nice setup Midnight Cow, thanks for posting it.

Cheers,
Brian

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