Prim Inspector & Transforms

The Prim Inspector is the low-level data portal for individual USD Prims. It allows you to peer into the underlying OpenUSD structure and perform surgical edits to spatial properties and asset relationships.

Transform Management

One of the most complex aspects of USD is its transform model. A single prim can have its final position determined by a stack of xformOps (Translation, Rotation, Scale, Matrices).

Preflight simplifies this by providing a unified Transform section:

• TRS Decomposition: Preflight automatically decomposes complex USD transform matrices into human-readable Position, Rotation (Euler degrees), and Scale components.
• Session-Layer Edits: When you modify a transform value, the change is not immediately written to the source file. It is staged in a temporary draft.
• The “Apply” Workflow: Clicking Apply Transform triggers a fix:setPrimTransform operation. This generates a new sub-layer in your current session that “overwrites” the base transform with your new values. This ensures your original source file remains untouched.

References & Composition

USD’s power comes from Composition Arcs, specifically References. The Prim Inspector makes these visible and manageable:

• Reference Stack: View every external file (.usd, .usdz, .abc) that is being referenced into the selected prim.
• Multi-Layering: You can see if a prim is a “local” definition or if it is being pulled from a library or another asset.
• Dynamic Addition: Use the Add Reference tool to link new assets into your hierarchy. This is essential for kitbashing or assembling complex scenes from individual components.
• Recursive Removal: Safely remove references to missing or broken assets to “repair” a scene that fails to load in other tools.

Core Attributes & Metadata

Beyond spatial data, you can inspect and modify the “Active” state and “Purpose” of a prim:

Attribute	Description	Impact
Path	The absolute hierarchy path in the stage.	Essential for AI Agent commands.
Active	Toggles if the prim exists in the runtime.	Used to “delete” objects non-destructively.
Visibility	inherited or invisible.	Controls viewport rendering.
Purpose	default, render, proxy, guide.	Links to Viewport Settings.
Kind	The component/assembly tag.	Essential for proper USD hierarchy categorization.

Authored Attributes Deep-Dive

For power users, Preflight lists every single property authored on the prim. This includes custom primvars, specific schema attributes (like doubleSided), and technical data that might not be exposed in a standard UI. This is your “source of truth” for debugging why a mesh looks incorrect in RealityKit.