Creating and accesing attributes

[caskal]

Hey magicians,

I'm playing with vellum and pressure, and I want to have more control by using color to control attributes. 

Lets say I have in red the zone I want to get "stretchstifness", my process was:

1. Color with attribute transfer
2. Attribute create "stretchstiffness" with value $CR
3. Point vop > bind import "stretchstifness" > fit range > bind export

Plug that into vellum but doesn't seem to work, also, what if I have several constraints (like cloth, pressure) how can I tell that the "stretchstiffness" is the one in Cloth and not pressure?

Lastly, inside "Vellumsolver" I have vellumconstraintproperty with animated restlenght in group @type=pressure to make the stuff inflate, how can I make the red color control the "restlength" attribute that is inside Vellumsolver?

 

Thanks!

[Andrea]

Recently I just started doing some tests with vellum and even if usually it was relatively simple to update geometry during the simulation in a DOP network, i found out that with vellum is not that easy.

I was trying to change the stiffness of some hairs. What I have noticed is that just using "Vellum Constraint Properties" is straightforward, maybe you can try use that?

 

Updating the geometry with a SOP solver mid-sim or even using a VEX expression in "Vellum Constraint Properties" reading and updating data from SOP as I was used to do with other solvers, is not working correctly. I still don't understand how is working under the hood, for sure I am missing something about it

[caskal]

On 24/1/2019 at 6:42 AM, Andrea said:

Recently I just started doing some tests with vellum and even if usually it was relatively simple to update geometry during the simulation in a DOP network, i found out that with vellum is not that easy.

I was trying to change the stiffness of some hairs. What I have noticed is that just using "Vellum Constraint Properties" is straightforward, maybe you can try use that?

 

Updating the geometry with a SOP solver mid-sim or even using a VEX expression in "Vellum Constraint Properties" reading and updating data from SOP as I was used to do with other solvers, is not working correctly. I still don't understand how is working under the hood, for sure I am missing something about it

Hey @Andrea thanks for the tips! I found this tutorial of Rohan about using attribute transfer to control vellum (around 13:18) but I'm still struggling

I also readed the doc for attributes, so far only thing I could do is freeze a group within a sop solver with i@stopped = 1 and animated that with a ch to make it work again.

Not sure why I can't control ie: restlenght within a sop solver wrangler, or for example, why if I move the group that has the i@stopped it doesnt unfreeze. Will keep playing

 

Here's my hip in case is useful for anyone:

of_vel.hiplc

 

Cheers!

 

Edited January 26, 2019 by caskal

[anim]

5 hours ago, caskal said:

Not sure why I can't control ie: restlenght within a sop solver wrangler

restlength is a primitive attribute of the ConstraintGeometry, but by default both SOP Solver and Geometry Wrangle run on Geometry data

so change SOP Solver/Data Name or Geometry Wrangle/Bindings/Geometry to Constraint Geometry and run over Primitives

 

5 hours ago, caskal said:

why if I move the group that has the i@stopped it doesnt unfreeze

because you are setting stopped to 1 on your group1, but you are not setting it to 0 for all other points

so when you move your group our of the way, it will simply not set 1 to any points, but there is nothing to set already stopped points to 0 so they stay stopped

[Andrea]

Thank Tomas, it worked out changing the Data Name. An additional step I had to do was to transfer the animated value to the hair constraint outside of the DOP network. Then in the SOP solver using an id to update them during the simulation.

[caskal]

Thanks for the tips @anim. It makes sense now  will keep playing with this and post a hip once I figure it out.

Cheers!