Skill: tomkrikorian/usd-editor (version 0.1.0)

--- name: usd-editor description: Guide for modifying USD ASCII (.usda) files, including prims, properties, composition arcs, variants, and transforms. Use when editing or reviewing .usda files by hand. --- # USD Editor ## Description and Goals This skill guides safe, minimal edits to USD ASCII (.usda) files and the proper use of official USD command-line tools. It focuses on preserving stage structure, using correct specifiers and property types, and avoiding composition mistakes while making targeted changes. ### Goals - Make precise edits without disrupting existing USD composition - Preserve file formatting and authoring style - Use correct prim specifiers, property types, and relationships - Avoid common USD pitfalls (wrong paths, missing xformOpOrder, broken connections) - Guide safe manipulation and inspection of USD assets using the command-line tools ## What This Skill Should Do When asked to modify a .usda file, this skill should: 1. **Inspect the stage structure** - Identify root prims, scopes, and relevant paths. 2. **Choose the correct specifier** - Use `over` for edits to existing prims, `def` for new prims. 3. **Edit only what is necessary** - Preserve unrelated content and formatting. 4. **Respect composition** - Avoid changing subLayers, references, or variants unless asked. 5. **Validate connections and paths** - Ensure `SdfPath` targets are valid and type-compatible. If the change is material- or shader-related for RealityKit, prefer the `shadergraph-editor` skill for node-specific guidance. ### Quick Start Workflow 1. Locate the prim path you need to edit (search by prim name or `SdfPath`). 2. Determine whether you should `over` an existing prim or `def` a new one. 3. Apply the smallest possible change (attribute value, relationship target, or child prim). 4. If adding transforms, update `xformOpOrder` to match your new ops. 5. Re-check any paths or connections you touched. ## Information About the Skill ### Core Concepts #### Stage and Layer A USD stage is composed of one or more layers. A .usda file is a single ASCII layer that can sublayer or reference others. #### Prim and Specifier A prim is a scene graph node. Specifiers control behavior: `def` creates, `over` modifies, `class` defines a reusable template. #### Properties Attributes store typed data; relationships (`rel`) point to other prims. #### Composition Arc Mechanisms like sublayers, references, and payloads that bring other USD data into the stage. #### SdfPath A path to a prim or property, written like `</Root/Child>` or `</Root/Mat.outputs:surface>`. #### List Editing USD list ops (`prepend`, `append`, `delete`, `add`) modify lists without replacing them. #### Variants Variant sets provide alternative content branches for a prim. #### Time Samples Animated or time-varying data stored in `timeSamples` dictionaries. ### Reference Tables | Reference | When to Use | |-----------|-------------| | [`usd-syntax`](references/usd-syntax.md) | When you need a refresher on .usda syntax, values, and path formats. | | [`prims-properties`](references/prims-properties.md) | When adding or editing prims, attributes, or relationships. | | [`composition-variants`](references/composition-variants.md) | When touching sublayers, references, payloads, or variant sets. | | [`transforms-units`](references/transforms-units.md) | When editing transforms, xformOps, or stage units/up axis metadata. | | [`time-samples`](references/time-samples.md) | When modifying animated/time-sampled properties. | | [`command-line-tools`](references/command-line-tools.md) | When you need a quick reference for common USD command-line tools. | | [`usdcat`](references/usdcat.md) | When converting, flattening, or inspecting USD files. | | [`usdchecker`](references/usdchecker.md) | When validating USD or USDZ assets, including RealityKit-focused checks. | | [`usdrecord`](references/usdrecord.md) | When rendering images from USD files. | | [`usdtree`](references/usdtree.md) | When inspecting the prim hierarchy of a USD file. | | [`usdzip`](references/usdzip.md) | When creating or inspecting USDZ packages. | | [`usdedit`](references/usdedit.md) | When you need the official text-editing workflow for a USD-readable file. | ### Implementation Patterns #### Override an Existing Prim ```usda over "Mesh" { token visibility = "invisible" } ``` #### Add a Simple Xform with Translate ```usda def Xform "Pivot" { double3 xformOp:translate = (0.0, 0.1, 0.0) uniform token[] xformOpOrder = ["xformOp:translate"] } ``` #### Bind a Material Relationship ```usda rel material:binding = </Materials/Mat> ``` ### Pitfalls and Checks - Don't replace a prim with `def` when you only need an `over`. - Keep `xformOpOrder` consistent with the ops you add or remove. - Verify `SdfPath` targets exist and match the expected property type. - Avoid editing composition arcs unless explicitly requested. - Preserve existing formatting and comments to minimize diff noise.


Security scan verdicts — ClawScan: clean | static analysis: clean | VirusTotal: clean | SkillSpector: clean (LOW)