[Sidefx-houdini-list] Houdini equivalent to Maya Wrap Deformer?

Marco Melantonio mmelantonio at gmail.com
Mon Aug 6 11:45:47 EDT 2018


Just to inform that Point Deform node gave a very decent result for my
purpose indeed.

The problem was with the reference and animated geometry. After a Boolean,
Clean and Convert Node, it worked properly.
Same techniques used in the Collisions Webinar by Jeff Wagner to prepare
geometries for collisions.
https://vimeo.com/252645795

I'm going to explore the other methods described too.
Thanks for all replies and suggestions.

Marco


Em qua, 25 de jul de 2018 às 12:40, Mathieu Leclaire <mleclair at hybride.com>
escreveu:

> I'm not sure I'm following you. Y position when it's on a flat XZ grid,
> sure, but if the object is more complex, I guess you mean using the
> distance between your point and the position from the xyzdist result?
> Even that won't always be consistent as the closest location normal
> won't necessarily be in the direction of where your point is. It's fine
> if your geometry is mostly smooth, but it there's a lot of noisy normal
> variations along the surface, it'll generally cause you problems.
>
> That's why point deform uses matrices. If you study the VEX code of the
> point deform, you can see it stores matrix transforms for each point
> from the Rest mesh to the Deformed mesh and then using your Capture
> settings, saves an array of point numbers and weights based on distance
> from your point to the Rest mesh points. Then basically it applies these
> matrix transform multiplied by the weight originally calculated. That
> means if you put Maximum Points to 1, then the point will be transformed
> like it's closest point while keeping the same offset transform. By
> adding more points in the Maximum Points, it simply smooth out the
> transform by multiple points. Point Deform is probably the node I use
> the most in Houdini, other then Attribute Wrangle.
>
> And if you want to keep most of your details from the original points
> while you point deform, you can always do the Delta Mush trick and
> smooth both your rest and your deformed meshes before using the point
> deform.
>
> Anyway, maybe I misunderstood what you meant, but for myself I use these
> tricks all the time all over my set-ups. It really depends on what you
> need to do.
>
> Cheers,
> -Mathieu
>
>
> On 25/07/2018 3:58 AM, Gerbrand Nel wrote:
> > Attribute transfer by UV?
> > I do this all the time. You just need to store the point Y position,
> > and then use that to push the points along the character's normals,
> > after the deformation.
> > G
> > On 2018/07/24 23:09, Mathieu Leclaire wrote:
> >> I'm not sure I fully understand what you want to do and why the point
> >> deformer isn't giving you good results.
> >>
> >> The point deformer saves a bunch of points and averages out the
> >> locations/offsets of your point from that list (it internally uses
> >> matrices and weighted distances to calculate the location with an
> >> offset), then reapplies the average on the deformed mesh. The point
> >> deformer will usually work very well to remap points from a static
> >> mesh to a deformed one, as long as they aren't too far away from the
> >> surface. If the results aren't good, you can subdivide both the
> >> static and deformed mesh to help smooth out the results.
> >>
> >> If you want a more custom VOP/Vex solutions, you can use XYZDist to
> >> find the closest location (returns a primitive number and a uv
> >> coordinate on that primitive) on a static polygon mesh (must be
> >> polygons, not polysoup or packed primitives) and then use Prim UV
> >> (named primitive attribute in VOP) to extract the same location on
> >> that animated mesh. Use P in the attribute field to extract the
> >> position. That will extract a position on the surface though. No
> >> offset information will be present there, so all points will stick to
> >> the surface.
> >>
> >> Hope that helps.
> >>
> >> -Mathieu
> >>
> >> On 23/07/2018 6:24 PM, Marco Melantonio wrote:
> >>> I'm trying to find a way to drive some animated particles (like an
> >>> organic
> >>> propagation growth) on an animated character.
> >>>
> >>> I did most of the effect RnD on static object. Now I'm trying to get
> >>> the
> >>> same result on an animated character. To do so first I cached the
> >>> simulation to be deformed by the animated version of the character.
> >>>
> >>> A similiar result can be achieved with the Maya Wrap Deformer.
> >>>
> >>> The best result I got in Houdini so far was with the point deformer
> >>> node,
> >>> but unfortunately it doesn't use the nearest point of the mesh, but a
> >>> random one.
> >>>
> >>> I tried to use the Lattice node too, but it's not working. Should be
> >>> missing some pass.
> >>>
> >>> I have tried a custom deformer too.. But not sure how to get the
> >>> nearest
> >>> point location on VOPs. Near distance node returns the point number
> >>> only.
> >>>
> >>> Does anyone have a clue or a tip?
> >>>
> >>>
> >>> Thanks
> >>>
> >>> Marco Melantonio
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