Placement & instances

Write Unreal placement transforms from both normal collection instances and evaluated Geometry Nodes instances.

Direct collection instances

Write Placement File scans visible scene objects whose instance_type is COLLECTION. If the instanced collection resolves to a Blending to Unreal asset reference, its world transform is written under that Unreal asset path.

Geometry Nodes instances

The placement writer also scans evaluated_depsgraph_get().object_instances. This is important because Geometry Nodes instances are evaluated instances rather than ordinary objects in bpy.data.objects.

The Bridge maps each evaluated instance back to the original source object/collection stamped with Blending to Unreal asset information, normalizes its transform against source geometry where needed, and de-duplicates matching placements.

Custom Depth & stencil

Direct collection instances expose Custom Depth and Stencil (0–255). For Geometry Nodes instances, the Bridge reads these values from the parent/source object that generated the evaluated instances when possible.

Placement file

The file is written beside the saved blend file as <BlendName>_PlacementData.txt. Each instance stores translation, scale, Euler rotation plus rotation basis vectors, Custom Depth and Stencil. Unreal performs the coordinate-system conversion on its side.

Visibility is respected: objects/collections hidden in viewport/render or excluded from the current view layer do not contribute placement actors.

LOD placement aid

The Placement section can assign LOD0–7 collections to an Empty and enable Collection LOD switching in Blender. This is particularly useful in separate placement files using linked/instanced asset collections.