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usage of "stamps()" expression in dop import node

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whats the purpose of using stamp expression in Dop import node . there are no variables called "DOPNET" , "OBJID" or "DATANAME"  in given path in "stamps" expression , if variable does not exist then it would return "value" which is the 3rd argument . so can't we directly put the "value" in parameter instead of using "stamps" expression

for example :

1). parameter =    `stamps(".." , "VARIABLE" , "value")`   .....(variable does not exist so eventually it would return "value")

2). parameter = "value"   .... (can't we put "value" straight in parameter instead of using "stamps" expression)


if I did not express m question  properly then just explain me why we are using "stamps" expression when we do not have any variable.


English is not my native language. sorry for any misunderstanding

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Posted (edited)
13 hours ago, ninipopo said:

there are no variables called "DOPNET" , "OBJID" or "DATANAME"  in given path in "stamps" expression

if there are no variables then yes, you can just put value and be done

however, if for example:

`stamps(".." , "OBJID" , "value")` on your dopimport node is inside of the DOP node, like SOP Solver, then '..' points to that DOP node (SOP Solver) and all DOP nodes have "DOPNET", "OBJID" variables initialized, SOP Solver has "DATANAME" variable too and many others, you can see all of that in Docs : http://www.sidefx.com/docs/houdini/nodes/dop/sopsolver.html

so in that case no, just putting value there may not work as expected for all cases, especially when dealing with multiple dop obects or data

you will not see the variable directly evaluated in the parameter, that will most probably always show fallback value as the variable can be different for every object processed by the node, etc, so it can't show all the different values at the same time, but the variable exists and will return correct value during cooking

Edited by anim
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so each dop node have some variables which stores some kind of data.

in this case sop solver have a variable called "OBJID"  (every object is assigned an integer value which is unique among all objects so by using "OBJID" we are specifying the object we are working with )

and variable "DOPNET" stores full path to dopnetwork like "obj/dopnetwork"

if I am wrong correct me and I have one more question,

Q) right now I'm working with particles . now sop solver have a variable called "DATANAME" which according to Docs means This is the name of the data on the object that is to be solved by the SOP Solver ,   But there is no data name on popobject  node but there is a parameter "popsource/Binding/Geometry" which store data name , so by object we are refers to popsource or pop object ?



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