Houdini 17.5 Dependency networks

pdg package

The classes and functions in the Python pdg package for working with dependency graphs.

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Package-level functions

The following top-level attribute functions are designed to be used in Python expressions. You can use pdg.workItem() to get the current work item object in a Python expression. The top-level function floatData(work_item, "foo", 0) is equivalent to work_item.data.floatData("foo", 0), which is equivalent to the HScript expression @foo.

Floats

Integers

Strings

Utilities

Expression functions

API

cooking

data

events

exceptions

  • pdg.CookError

    Generic exception raised when an error running the graph.

expressions

  • pdg.EvaluationContext

    A module with global functions that operate on the thread-local evaluation context

nodes

schedulers

  • pdg.Scheduler

    A scheduler object that has its type implemented in Python.

types

  • pdg.language

    The enumeration of languages used to define custom PDG types

  • pdg.registeredType

    The type of object when registering a custom class with PDG

  • pdg.result

    The return type of a node callback implementation

  • pdg.scheduleResult

    The return type of a scheduler’s onScheduler callback implementation

workitems

Dependency networks

Basics

Next steps

  • Running external programs

    How to wrap external functionality in a TOP node.

  • File tags

    Work items track the "results" created by their work. Each result is tagged with a type.

  • Feedback loops

    You can use for-each blocks to process looping, sequential chains of operations on work items.

  • Command servers

    Command blocks let you start up remote processes (such as Houdini or Maya instances), send the server commands, and shut down the server.

  • Integrating PDG and render farm software

    How to use different schedulers to schedule and execute work.

  • Visualizing work item performance

    How to visualize the relative cook times (or file output sizes) of work items in the network.

  • Tips and tricks

    Useful general information and best practices for working with TOPs.

Reference

  • All TOPs nodes

    TOP nodes live inside TOP objects and do work.

  • Python API

    The classes and functions in the Python pdg package for working with dependency graphs.