houdini-hda-creation

houdini-hda-creation

Version: 1.1.1 Last Updated: 2026-10-09 Dependencies: Houdini 20+, Python 3.9+

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CRITICAL: MANDATORY FIRST STEP

ALWAYS verify Houdini environment before execution:

# Check Houdini installation
where houdini

# Verify Houdini version
houdini --version

# Check if Houdini is running (Windows)
tasklist | findstr "houdini"

Why Critical:

• Asset Corruption: Creating HDAs while Houdini is saving can corrupt asset definitions
• Version Compatibility: HDAs created in newer Houdini versions may not work in older versions
• Path Requirements: HDA libraries must be accessible via HOUDINI_PATH or $HIP

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QUICK START

Most Common Use Case: Create Basic HDA

Goal: Convert a subnet into a reusable Houdini Digital Asset

Step 1: Validate Environment

import hou

# Check Houdini session is active
if not hou.hipFile.isLoadingHipFile():
    print("Ready to create HDA")
else:
    print("Wait for file to finish loading")

Step 2: Prepare Node Network

# Select the subnet you want to convert
subnet = hou.node("/obj/my_subnet")

# Verify subnet exists and is valid
if subnet and subnet.type().name() == "subnet":
    print(f"Valid subnet: {subnet.path()}")
else:
    raise ValueError("Invalid subnet selected")

Step 3: Create HDA from Subnet

# Define HDA properties
hda_name = "my_tool"
hda_label = "My Tool"
hda_file = f"$HIP/hda/{hda_name}.hda"

# Create the digital asset
subnet.createDigitalAsset(
    name=hda_name,
    hda_file_name=hda_file,
    description=hda_label,
    min_num_inputs=0,
    max_num_inputs=1
)

print(f"HDA created: {hda_file}")

Step 4: Verify Success

# Check HDA definition was created
node_type = hou.nodeType(hou.objNodeTypeCategory(), hda_name)
if node_type:
    print(f"HDA type registered: {node_type.name()}")
    print(f"Definition file: {node_type.definition().libraryFilePath()}")
else:
    print("ERROR: HDA not registered")