The Problem
When attempting to make a placeable that provides both animation & transparency through to the rest of the mesh below via texture information file, such as a plane of water, the usual result is that the mesh with the .txi texture assigned occludes any part of an NPC below it in the model. For this example, we'll use a rectangular tub of water made up of a bottom, the tub walls, and a simple plane for water that uses the stock Bioware TTR01_water01.tga which calls the accompanying TTR01_water01.txi. For demonstration of behavior, there is a plate placeable in the tub below the water level, and a human NPC standing in the water.
The model pictured above is exported from NWMax with a Classification = Character, as are all placeables. The legs of the NPC are occluded from the knee down, but the separate model of a placeable plate is visible.
The Solution
Bioware included a special dummy node (Empties in Blender) that allows animation via .txi files to work without occluding content viewed through it if there is transparency. This dummy node takes the name of the model with "a" appended to the end, and is positioned as a child of the aurorabase and parent to the mesh with the .txi texture assigned. In order for this method to work, on the NWMax rollout (or equivalent Neverblender setting), you must select Classification of Other or Tile (if your model is exploding into pointy bits using Other, try using Tile before editing your model).
The Particulars
In addition to establishing the hierarchy correctly, this method only works properly in Non-Static placeables if the animation dummy node and mesh with .txi associate texture are the last node in the mdl file. This is accomplished by linking the new dummy last, or by breaking links and reordering. It can even be done with copy/paste in a plain text editor of your choice on a mdl file.
ResetXForm
ResetXForm rearranges the order of the nodes in your model, as it unlinks then relinks the piece on which you perform the action, changing the order in the schematic view.
Here are examples of how the hierarchy and node order affect the transparency – the pictures of the model show non-static on the left and static on the right:
Correct
The hierarchy of the model
Both non-static (L) and static (R) work properly, as the special node is last in the model hierarchy.
TXI in the middle
Bad hierarchy, with one mesh after the special node.
Because the bottom of the tub is after the special node in hierarchy, it is not visible. Note that the tub walls are physically below the plane of water but are still visible because they are procedurally above (before) the special node in the model hierarchy.
TXI on top
Bad hierarchy, with both meshes after the special node.
Any part of the model viewed through the mesh is occluded, as all model parts (meshes) come after the special node in hierarchy.
