quick way to keep attribute the same value

[stephenl]

What is a quick way to make an attribute stay the same after it receives a value. I get data from dops on frame 8 and I want the value to stay the same after the collision ends on the next frame.

I've tried this in a detail attribute create:

if collision happens
  get data
if not
  be equal to this detail

But it erases on the next frame.

Thanks.

[asnowcappedromance]

SOP Solver is the way to go, or in Houdini 12 you can take advantage of the Solver SOP.

Do a quick search and you will get plenty results on how to handle this!

best,

Manu

[stephenl]

I forgot to mention it is in a SOP solver. I just need an expression that holds a value once it receives one. I'm sure it is something simple I can't think of

Edited March 17, 2012 by stephenl

[SpencerL]

I forgot to mention it is in a SOP solver. I just need an expression that holds a value once it receives one. I'm sure it is something simple I can't think of

Probably would help to see a file, but one thing to make sure is that you are not creating the attribute inside the sop solver before doing the check or else each frame the attribute would get reset. Best to create any attrs before feeding it into the solver.

[Mzigaib]

You can try:

if ($COLLISION == 1,$DATA,detail(surface_node, attrib_name, attrib_index))

But like Manuel said this will be reseted at the next frame to maintain accumulation of the values you have to use SOP solver.

I hope this helps.

Cheers!

[stephenl]

Edit: I got it to work. Use apply data with empty data going into the data input, and modify data after apply data. In modify data create 3 variables, x,y,z and now the expression works. I was trying to get fields to hold values but I guess you can't and actually need data.

if(
dopfield($DOPNET, 1, "Impacts", "Impacts", 0, "positionx") != 0,
dopfield($DOPNET, 1, "Impacts", "Impacts", 0, "positionx"),
dopoption($DOPNET, $OBJID, "hitpos", "x"))

where hitpos is the name of the data and x is the name of the subdata

Edited March 18, 2012 by stephenl

[Sifis]

Edit: I got it to work. Use apply data with empty data going into the data input, and modify data after apply data. In modify data create 3 variables, x,y,z and now the expression works. I was trying to get fields to hold values but I guess you can't and actually need data.

Hey Stephen, Can you post a simple hip using this trick?