houdini-material-library

houdini-material-library

Typed material-library tools that complement houdini-materials (material create/assign) and houdini-lookdev (shader-network editing and adapter-owned presets).

Tool groups

• library-presets: save_material_preset, load_material_preset, list_material_presets, delete_material_preset — JSON files under a user-supplied library_dir (defaults to ~/.dcc-mcp/houdini/material_library/, override with DCC_MCP_HOUDINI_MATERIAL_LIBRARY_DIR).
• library-textures: assign_texture, list_images, reload_image.
• library-color: set_color_management, list_color_spaces (both read Houdini's OCIO configuration).
• library-query (read-only): get_material_connections, get_shader_assignment.

Context limitations

• Presets vs lookdev presets: This skill operates on a library directory (library_dir) — independent of the houdini-lookdev adapter-owned preset store. A library preset captures the full node type and all settable scalar parameters; lookdev presets capture evaluated values only. Choose the library path when sharing across projects; choose lookdev presets for quick per-user snapshots.
• Texture mapping: assign_texture uses built-in texture controls on principledshader nodes, updates only the typed file-path parameters on mtlximage and arnold::image, or creates the matching image node for an exact input on mtlxstandard_surface and arnold::standard_surface. The texture must remain one regular, non-linked local file through every guarded mutation and readback. Digest work is limited to one initial pass, a 256 MiB file ceiling, and an elapsed-time budget checked before and after every read, including EOF. On Windows, a native read lease denies writes and replacement until mutation, final readback, and undo exit complete; later guards recapture physical identity metadata. Owned image nodes are bound to a durable material identity plus node, input, and Houdini session identity; stale or duplicate ownership fails closed. Every touched parameter, input, and newly created node is rolled back if mutation or post-mutation verification fails. Other node types and missing parameters fail closed without fallback wiring.
• OCIO: list_color_spaces reads from Houdini's active OCIO config; set_color_management sets the OCIO environment variable and triggers a Houdini refresh when possible.