houdini-solaris-usd

houdini-solaris-usd

Version: 1.1.1 Last Updated: 2026-10-10 Dependencies: Houdini 20+, USD libraries

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CRITICAL: MANDATORY FIRST STEP

ALWAYS verify USD stage context before operations:

# In Python LOP or Python SOP
from pxr import Usd, UsdGeom, Sdf

# Get stage from node
node = hou.pwd()
stage = node.editableStage() if hasattr(node, 'editableStage') else None

if not stage:
    print("ERROR: No USD stage available")
else:
    print(f"Stage root layer: {stage.GetRootLayer().identifier}")
    print(f"Prim count: {len(list(stage.Traverse()))}")

Why Critical:

• Stage Required: USD operations need active stage context
• Layer Stack: Understanding layer composition prevents unexpected overrides
• Path Validity: Invalid USD prim paths cause silent failures

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QUICK START

Most Common Use Case: Create USD Scene from SOPs

Goal: Convert SOP geometry to USD stage with materials and hierarchy

Step 1: Create SOP Geometry

[SOP Network]
- Grid -> Mountain -> Scatter -> Copy to Points
- Create geometry in /obj/geo1

Step 2: Create Stage and Import

[/stage Context]
v
SOP Import LOP
- SOP Path: /obj/geo1/copytopoints1
- Import Path Prefix: /World/geometry
- Primitive Kind: component

Step 3: Add Material

Material Library LOP
- Create Material: usdpreviewsurface1
  - Base Color: 0.7, 0.5, 0.3
  - Roughness: 0.8
v
Assign Material LOP
- Primitives: /World/geometry/*
- Material: /mtl/usdpreviewsurface1

Step 4: Set Hierarchy and Metadata

Configure Layer LOP
- Set Default Prim: /World
- Set Layer Comment: "Procedural scatter geometry"
v
Add Variant LOP (optional)
- Primitive Path: /World/geometry
- Variant Set Name: "detail_level"
- Variants: high, medium, low

Step 5: Export USD

USD ROP (Render Output)
- Output File: $HIP/usd/scene.usdc (binary) or .usda (ASCII)
- Save Style: Flattened Stage (bake all layers into one)
  OR
  Separate Layers (preserve layer stack)