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Python SOP, in what order does Houdini evalute it?


valdomat

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I had an issue with a Python SOP setting the file parameter of an other node, where the Python sat above/before the effected node. Resulting in a broken and somewhat random behavior. This was done in a for loop. 

What seams to have fixed it was to move the Python SOP to execute under/after the effected node. Could someone explain the order of how nodes are executed? Is it that the nodes are evaluated from bottom up and then executed? 

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Python SOP should not modify any node parameters, this SOP is for manipulating geometry. For modifying parameters - use expressions

 

To answer your question:

12 hours ago, valdomat said:

Could someone explain the order of how nodes are executed? Is it that the nodes are evaluated from bottom up and then executed? 

 

Houdini networks are DAGs and the order is on Houdini's discretion, based on what has been already cooked and/or changed.

In most cases, you should not be building network logic based on nodes order, it's very error prone.

 

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On 2/2/2021 at 11:56 PM, Stalkerx777 said:

Python SOP should not modify any node parameters, this SOP is for manipulating geometry. For modifying parameters - use expressions

Thank you for the reply! That makes a lot of sense, since asking I did turn to expressions with solid results. 

 

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