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LexDWills

Applying Velocity (a very n00b question)

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I apologize in advance for the n00bishness of this question - I am still very new to Houdini, and though I am trying to find answers myself online, in some instances (like this) I don't know enough to know what to search for.

What I'm trying to do: for a polygon, make the velocity attribute of each point effect the position of that point - i.e., actually make the velocity attribute have an effect.

I have attached the file I'm working with. What it does is receive a model of a dress, group it into different parts (the stiff bodice, the main skirt, then the parts on top of the skirt (sash, ribbon and flower)). Then does a cloth style simulation of the main skirt only (using a spring node). Then using attribtransfer, the velocity of the points of the moving skirt is transferred to the points of the static models hanging over the dress (the sash, ribbon and flower).

My goal is to have the simulation of the moving skirt, drive the movement of the non-simulated bits of material hanging over and around the skirt, so that the extra details attached to the skirt will move with the skirt (without needing their own simulations to work) - so that when the skirt bends and creases and ripples, the sash/ribbon/flower bend and crease and ripple as well.

The funny thing is - the attribute transfer node works. The sash/ribbon/flower all receive their velocity values from the skirt (have proven this by using a vopSOP to color all points using their velocities). The velocity attribute and values are there for each point. The points just don't move - the velocity values are having no effect on the position of each point.

I am sure I am doing something really obvious and really stupid - not ticking the right box or applying the right node to tell Houdini to apply the velocity to the point positions. But I don't know what obvious and stupid thing I am not doing, as I am still too new to Houdini.

Anyone's help would be greatly appreciated.

File attached below (Houdini 12 file), and obj being used can be downloaded from here: https://www.dropbox....11_sansCage.obj

Thank you in advance.

FTE_v003_clothSim_v001_newDressImport.hip

Edited by LexDWills

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Well obviously I can't do your scene for you because we don't have the objExport of the Dress...

However you should just be able to use a lattice to do this, possibly set to points mode with a larger radius.

Left input your objects go into.

Middle Input is your un-simmed, totally static dress.

Right input is your simmed/animated dress.

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Note that there's also the recently added ClothCapture/ClothDeform SOPs.

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Sorry I didn't pay attention.

Here it is with the lattice.

THANKYOU^3 - is now working:

https://dl.dropboxusercontent.com/u/11645479/Dress%20Velocity%20Transfer%20Test%2002.avi

Some slight clipping issues with the sash but need to alter the model anyway (director wants more folds).

But it is a working prototype, at long last. Again, THANKYOU THANKYOU THANKYOU!

Note that there's also the recently added ClothCapture/ClothDeform SOPs.

Will definitely google the hell out of both of those. Tried following the Cloth masterclass but had issues with the whole still being new to it thing (spent a day trying, in vain, to figure out how to select primitives on a simulated object). But will look into those sops, thankyou!

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Will definitely google the hell out of both of those. Tried following the Cloth masterclass but had issues with the whole still being new to it thing (spent a day trying, in vain, to figure out how to select primitives on a simulated object). But will look into those sops, thankyou!

The tutorial is great although remember that the current cloth object-DOP has different attributes and attribute names then those in the tutorial. If you hold the pointer of your mouse on top of the parameters in the cloth object-DOP it will show you the attribute names for that parameter. These can then be accessed in SOPs.

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Guest tar

Tried following the Cloth masterclass but had issues with the whole still being new to it thing (spent a day trying, in vain, to figure out how to select primitives on a simulated object). But will look into those sops, thankyou!

It's quite alarming/interesting that it can be easier to simulate cloth than select components! You should be able to use the Select tool set to primitves, press 'S' then '2'. Does that work?

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