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dtarr77

Fractured Cloth Activation By Color Attribute?

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Hi guys,

 

Currently, I am working on a project where I need a way to get a fractured geometry cloth simulation to activate each fracture piece according to the color attribute.  The plan is that a curve, representing the path of another object's motion, will pass through the fractured object causing it to begin floating away and disintegrating from the point of impact/contact. 

 

I am still learning Houdini and have only been working in it consistently for about 6 months or so, but I have the effect mostly working with the disintegration and cloth simulation and such.  What I can not seem to figure out is how to activate the pieces as the color envelopes the object.  I have found other forums posts that have given some good routes (That's where I got the color transfer route to where it is currently at) but they are for fractured RBD objects and I have not been able to get those to work for a cloth object in DOPs.  I have the color working in SOPs but just need help getting that into DOPs and controlling the activation of each piece.  I have created an example file and attached it below.  Thank you in advance for any help/advice you guys can provide.

 

Thanks,

Dustin

 

P.S. As a bonus problem solve:  one piece seems to get stuck on nothing, as if it is constrained to an invisible point in space, but it has no constraints.  I am not sure why yet.   I'm going to keep looking into the issue, but if anyone knows why please let me know.  Thanks.

 

ClothFracture_Test.hiplc

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Hello Juraj Tomori,

 

Thank you for replying, I am going through your example file and trying to adapt your process to my situation, but I am running into an issue where the "test" group node (named "release_grp" in my file) inside the SOP solver of the DOPs network is not liking the $FRACTURETHRESHOLD != 1 expression.  I have tried my best to keep it as similar to yours as my particular situation will allow but now I think I am in over my head a little.

 

As far as I can tell, the only thing that MAY be essentially missing, or different, is my route of fracturing.  I do not have the fracturepart attribute due to using voronoi fracture because I did not like the solid fracture results for my situation. I do not know if that matters, but I thought maybe I could convert the name attribute for my pieces to the integer attribute of fracturepart like in your scene.  Unfortunately, I have not found a way to do so outside of an expression that I do not know how to apply yet. The POP force also does not seem to want to see "release_grp" group inside of the SOP solver.  I tried with a working group (no expression) and it still does not see it.  At the moment, what simulation is happening is very strange an erratic.  So I have a few questions:

 

- How do I convert the name attribute (string type attribute I believe, right?) of my fractured pieces into the integer attribute, fracturepart?

 

OR

 

- What am I missing that is causing this not to work in my scene?  (see attached example file of my test scene attempt at your process)

 

- If I use your route just to get the color attribute in like my original idea, how do I tell a dynamic group node to only use color?  It seems the expression area of the "Group Dynamic Objects" node works much differently than the SOP group node, and the "Active Value" node does not see any group nodes inside of the SOP Solver nor the original SOP geo.  It does seem to see color now, but I do don't know how to call that up in the group or Active Value node with my currently very limited scripting/expression skills. 

 

I will be very grateful for any help you can provide.  Thank you again, Juraj.

 

Dustin

 

 

(Also, if you are able to look at the file, beware of the visualize energy node, seems to almost crash Houdini for some reason if you try to play or skim the timeline.  Possibly due to whatever is keeping it from working.)

ClothFracture_Test_v02.hiplc

Edited by dtarr77

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Hi,

I recreated this setup and I tried to keep it simple :)

I voronoi-fractured sphere, in simulation I import Cd attribute from SOPs and use it as mask for applying force and noise. I also remove red points from group of constrained points.

 

Juraj

jt_fracture_cloth.hipnc

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Juraj,

 

I just went through the file, that is amazing!  Thank you so much!  This is exactly what I was looking to do.  I would have never thought of the Geometry Wrangle with my current level of experience but it makes perfect sense.  I applied it to my scene and after some tweaking to fit it to the situation it looks like it is working. :)  Thank you again Juraj.  It is a HUGE help and very educational as well.

 

Thanks,

Dustin

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