feat: link identical object copies as instances

[BenJule]

Summary

Add a context-menu action that converts selected identical object copies into linked instances of a single object.

This provides the inverse workflow of Set as individual objects and is useful when independent copies created through cloning or copy-based bed filling should share the same object geometry and settings again.

Changes

• Add Link selected copies as instances to the multiple-object context menu.
• Keep the selected object with the lowest model index as the master object.
• Copy the instance transformation of every other selected object to the master.
• Remove the converted source objects in descending index order.
• Rebuild the instance hierarchy in the object list.
• Preserve plate assignments and printable states.
• Refresh the 3D scene, assembly view, PartPlate data, slicing state, and sidebar controls.
• Store the complete conversion as a single undo operation.

Compatibility checks

The action is only available when all selected entries are complete object nodes and can be converted without losing object-specific information.

Each selected object must:

• contain exactly one instance
• use the same number and order of volumes
• share the same underlying mesh allocations
• use identical object and volume configurations
• use identical volume types, materials, and transformations
• use identical layer ranges and layer-height profiles
• use identical support, seam, fuzzy-skin, MMU, and exterior facet annotations
• use compatible assembly metadata

The action is disabled for:

• SLA objects
• cut objects and cut connectors
• editable text or SVG volumes
• objects with individual brim points
• objects with SLA support points or drain holes
• separately imported meshes that merely have similar geometry

Mesh pointer equality is intentional. It identifies actual Bambu Studio object copies and prevents unrelated imported objects from being linked accidentally.

Transformation preservation

The conversion preserves each source instance's:

• position
• rotation
• scaling
• mirroring
• printable state
• plate placement

The operation does not call ensure_on_bed(), preventing the converted instances from being shifted vertically.

Validation

• git diff --check
• targeted compilation of:
  • GUI_ObjectList.cpp.o
  • GUI_Factories.cpp.o
• repeated Ninja build returned no work to do
• no compilation errors were reported

A full application build and interactive UI test have not been performed.

[Haidiye00]

Hi, please record the GIF effect after the changes, thanks

[BenJule]

Here you go:

[Haidiye00]

Hello, we are very sorry, but bambuStudio is currently designed to not support multiple instances. Multiple instances of objects may cause new problems.