arnold_api.md

Memo Arnold API

Useful links

• https://help.autodesk.com/view/ARNOL/ENU/?guid=arnold_dev_guide_home_html
• https://help.autodesk.com/view/ARNOL/ENU/?guid=Arnold_API_REF_arnold_ref_index_html
• https://arnoldsupport.com/2014/12/11/arnold-python-changing-arnold-options-in-python/
• https://arnoldsupport.com/tag/python/
• https://arnoldsupport.com/category/scripting

Python environment

Using rez and pycharm:
rez env arnold pycharm -- pycharm

Test:
rez env arnold -- python -c "import arnold;print(arnold)"

Pythonpath needs to know about the API, for example from HTOA or MTOA

• HTOA\htoa-XXX\scripts\python
• MTOA\mayaXXX\scripts

Usage examples

Changing OCIO setting in a series of ass files

from pathlib import Path

from arnold import *
import os

path = Path("//path/testpipe/shots/s01/p010/lighting_main/publish/v000/ass/main/renderSetupLayer1__test")

for ass_file in list(path.glob("*.ass"))[:]:

    AiBegin()

    AiMsgSetConsoleFlags(AI_LOG_ALL)
    AiLoadPlugins(os.getenv('ARNOLD_PLUGIN_PATH'))
    # universe = AiUniverse()

    # getting ass options
    options = AiUniverseGetOptions()

    print(f"Handling {ass_file.name}")

    # converting pathlib.Path to string
    ass_file = str(ass_file)

    # loads Ass
    AiASSLoad(ass_file, AI_NODE_ALL)

    # get options
    color_manager_node = AiNodeGetPtr(options, "color_manager")
    print(f"color_manager node name: {AiNodeGetName(color_manager_node)}")

    # this is to get the options explicitly by node name
    # color_manager_node = AiNodeLookUpByName("defaultColorMgtGlobals")

    # updating the node
    AiNodeSetStr(color_manager_node, "config", "//path/rez/packages/tools/aces/1.2/config.ocio")

    # write updated ass file
    AiASSWrite(ass_file, AI_NODE_ALL)

    AiEnd()