Edit NURBS UVs

Maya provides limited support for editing the UV texture coordinates of NURBS surfaces within the UV Editor. Edit NURBS UV mode is useful for games developers who use NURBS surface types in games applications and require the ability to modify an explicit UV set for subsequent export to a games engine. This feature does not provide support for editing NURBS UVs for use with texture mapping or image rendering features within Maya.

Edit NURBS UV mode creates an explicit and unique UV set for the NURBS surface. The user switches between the implicit UVs for the NURBS surface and the explicitly created UV set. It is then possible to edit the explicit NURBS UVs on a limited basis.

It is recommended that you create and edit the explicit NURBS UVs only when all editing and modification of the NURBS surface model is complete. See the Notes and Edit NURBS UVs Limitations below.

For more information on the MEL ^TM commands and flags that provide this functionality, see the nurbsUVSet, nurbsEditUV commands in the MEL guide.

To edit UVs for a NURBS surface in the UV Editor

1. In the scene view, select the NURBS surface that you want to create and edit explicit UVs for texturing.
2. Ensure that the construction history for the NURBS surface is deleted by selecting Edit > Delete All by Type > History.

   Deleting construction history prior to making any UV edits ensures that subsequent updates to the node dependency graph do not remove the UV edits you make to the explicit NURBS UV set. Do this only when you are sure you will no longer be required to edit the model (Save a copy of the model that contains construction history in case you need to revert back for any reason).

3. Turn off construction history while you work on the NURBS UVs using the Construction History on/off icon on the Status Line.
4. Open the UV Editor by selecting UV > UV Editor.

   The NURBS UVs that are implicitly created with the NURBS surface appear in the 2D view of the UV Editor.

5. In the UV Editor, right-click in the 2D view, and select Edit NURBS UV mode from the marking menu that appears.

   A UV set for the NURBS surface is explicitly created and displayed in the 2D view of the UV Editor. The NURBS UV set created is based on the topology of the NURBS surface.

6. Change the selection method to UVs by doing one of the following:
   • Right-click in the scene view and select Surface UV from the marking menu.
   • Right-click in the 2D view of the UV Editor, and select UV from the marking menu.
7. Select the UVs you want to modify in either the scene view or in the 2D view of the UV Editor.
8. Using the transformation tools from the Toolbox (Move Tool, Rotate Tool, or Scale Tool), edit the position of the NURBS UVs in the UV Editor.

Notes

• Deleting the construction history on the NURBS surface is a requirement prior to creating and editing the explicit NURBS UVs. This ensures that updates to the dependency graph do not overwrite UV edits.
• Modifying the NURBS surface topology in any way (that is, inserting an isoparm on the NURBS surface) after the explicit UV set has been modified will overwrite the unique NURBS UV set. The explicit NURBS UV set will be updated to take into account the changes to the topology, but any UV modifications will be lost.

Edit NURBS UVs Limitations

• The explicit UV set created with this feature is unique for each NURBS surface. That is, unlike polygon and subdivision surface types, it is not possible to create multiple NURBS UV sets for a given NURBS surface.
• The Maya renderers (software, hardware, and so on) do not support explicit NURBS UVs. They are only capable of rendering the implicit UVs for NURBS.
• Construction history is not supported. That is, a user should plan their texturing workflow to occur after all edits and modifications to the model are complete. Changing the topology of the model after the NURBS UV set has been edited will overwrite the UV edits whenever the node dependency graph updates.
• UV modification is limited to UV selection and transformation only (that is, move, rotate, and scale). It is not possible to select and modify the explicit NURBS UVs by patch or isoparm. The polygon and subdivision surface UV modification features do not work with the explicit NURBS UVs.
• UV sharing is not supported. With explicit NURBS UVs a UV texture coordinate exists for each patch corner on the surface. A bounding box selection can be used to move interior NURBS UVs simultaneously.