Importing and Exporting with Crosswalk for Max

Merging Scene Elements

In the Update\Import Options dialog box, deselect the Update existing scene elements checkbox if you want to import using the merge mode. Merging scene elements can be useful in the following situations:

• You are importing a dotXSI file into an empty 3ds Max workspace. In other words there is nothing to update, you are simply adding all elements in the dotXSI file to a new/untitled scene.

• All modifications and the subsequent output of the scene file will remain within a 3ds Max workflow.

• You want to make sure that the data in your currently open 3ds Max scene remains untouched and that the dotXSI file being imported is simply merged as is.

• You made modifications to the original Max scene after exporting it to dotXSI and now you want to re-import the dotXSI file to merge it back without updating any of the modified scene elements.

• You have two dotXSI files that may contain scene elements with the same name but are not the same objects. You want to import both files but you do not want to update/replace objects in the first file by objects (with the same name) in the second file.

• You want to use the merge mode as a way of duplicating a scene.

• You want to preserve vertex user data (this data gets overwritten when updating scene elements).

Updating Scene Elements

In the Update\Import dialog box, select the Update existing scene elements checkbox if you want to match and update scene elements in the dotXSI file with scene elements in the 3ds Max scene.

The update process looks inside the currently open 3ds Max scene for elements that "match" with elements that are being imported. When matches are found, the elements in the 3ds Max scene are replaced by the ones being imported in the dotXSI file.

Matching and updating occurs during import, but accurate matching also relies on the export mechanism (see How Scene Elements Are Matched).

The basic updating workflow is as follows:

1. In 3ds Max, choose File Import from the main menu.

2. Save (and modify if required) as a 3ds Max scene.

3. Export from 3ds Max to dotXSI (see Exporting to dotXSI).

4. Save the current 3ds Max scene.

   Exporting to dotXSI creates special user properties in the exported dotXSI file and also adds them to the 3ds Max scene itself. These properties ensure accurate matching of scene elements. Make sure you perform all subsequent updates on the 3ds Max scene containing these user properties. For more information, see How Scene Elements Are Matched.

5. Import the modified dotXSI file back into 3ds Max.

6. In the Update\Import dialog box, select the Update existing scene elements checkbox.

   If no matching scene elements are found, the scene elements are imported as new scene elements. New scene elements are merged into the current scene.

   In the case where a new scene element is a child of a matched element in a hierarchy, it will be inserted as a child of the existing element. A new hierarchy is not created.

7. Select the scene elements and attributes you want to update:

   Mesh: Update mesh topology, vertex position, user defined normals, vertex color, texture coordinates, skin weight data, and morph targets.

   If custom per-vertex data or custom per-polygon data is present on the matched original mesh, they will be lost (overwritten).

   Transformations: Update transformations, hierarchies, and animation.

   Re-link Original Material: Use the matched original material instead of importing a new one. The existing material property will not be changed.

8. Click OK.

How Scene Elements Are Matched

Every object (node) that gets imported or created in 3ds Max is assigned a unique identifier called a node handle.

On export, the node handle is stored in a user property labeled XSIProp_NodeHandle on the corresponding 3ds Max object (node) in the exported dotXSI file as well as in the 3ds Max scene itself. You must save your 3ds Max scene immediately after you export to dotXSI to preserve the property and use this scene to perform all subsequent updates. When the XSIProp_NodeHandle property is present in the scene you get more reliable matching of elements.

Scene elements are matched, first, based on the XSIProp_NodeHandle user property, second, matched on the current Max node handle, and then finally matched by object name.