general houdini workflow question of solver node when trying to print in pytjon

[cloudamy]

Hi, I have a general question about the workflow of houdini of solver node.

I created a volume with a vector field called h, and I tried to update h at each time step using a solver node, and then I tried to print using a python node to see if h got modified, but it is not, it is still the initial value. Can someone explain to me why this is the case? Thanks a lot!

[bunker]

your display flag should be on the volumewrangle and the input of that node should be Prev_Frame OR Input_1

Edited July 29, 2020 by bunker

[cloudamy]

9 hours ago, bunker said:

your display flag should be on the volumewrangle and the input of that node should be Prev_Frame OR Input_1

Ohhhh! Thank you so much! 

When I put the display flag on the volumewrangle, it somehow says that my vector is a float??? Here I attached a screenshot of my volume h and the error message

If possible, can you also explain to me what's the relationship between prev_frame and input_1 or guide me to where I can learn about it myself?

[bunker]

maybe post a hip file

[cloudamy]

7 minutes ago, bunker said:

maybe post a hip file

Here it is!

Thank you so much!

example.hipnc

[eimk]

In the volume wrangle you need to specify that 'h' is a vector by using 'v@h' rather than just '@h'. VEX assumes everything is a float unless told otherwise, or if it is one of a few specific attributes like Cd.

This page has some helpful info on attributes in VEX https://www.sidefx.com/docs/houdini/vex/snippets#attributes

[cloudamy]

1 hour ago, eimk said:

In the volume wrangle you need to specify that 'h' is a vector by using 'v@h' rather than just '@h'. VEX assumes everything is a float unless told otherwise, or if it is one of a few specific attributes like Cd.

This page has some helpful info on attributes in VEX https://www.sidefx.com/docs/houdini/vex/snippets#attributes

Oh! Ok, thank you!