BSLODTriShape Improvements

[hexabits]

I've come upon the realization that no tool exists which can reliably edit BSLODTriShapes. Here is the problem summed up in a diagram:

Level 2 = Should disappear first Level 1 = Should disappear second Level 0 = Should never disappear

Add/Delete Issues

1. Your 3D program might not add the triangles where you want them.
2. Your 3D program might shuffle the entire triangle order.
3. Which triangles are associated with which LOD level are lost on import.

Fixing this by hand would essentially be impossible, especially if the vertex order changes. The Triangle listed as using vertices 0,1,2 might not be the same as before, so you have no way of manually rearranging the triangles.

The artifacts from improper BSLODTriShape editing are primarily mesh holes from not increasing the triangle counts, or incorrect LOD switching behavior. If what used to belong in Level 0 is now in Level 2, it will disappear when it shouldn't. It's likely that the triangle was in Level 0 for a reason (it should never disappear, i.e. it's very visible).

The current "solution"

• In the case of new triangles, you just add the number of new triangles to any of the LOD levels. For example in the diagram, if you add 2 to Level 0 Size, your LODs will be split 8/4/2. In the case of the diagram this actually solves the issue, unless you wanted the 2 new triangles to be in LOD2 instead of LOD0.
• In the case of deleted triangles there is nothing to do really because it's unlikely you will know exactly what numbers to subtract from which LOD level.
• HOWEVER, if in either case the triangles are rearranged completely, there is no saying what the state of the LODs is like. In that case you should just put ALL the triangles into Level 0.

  The real solution is multi-part

  1. NifSkope should be able to convert a BSLODTriShape to 3 NiTriShapes. It should append ":LOD0", ":LOD1", and ":LOD2" to each level's new NiTriShape.
  2. You can now import the levels separately into your 3D program. Your 3D program might even have tools for treating 3 separate objects as 1 LOD object if you would like to visualize the LOD behavior in the program.
  3. NifSkope should be able to create a BSLODTriShape from 1-3 NiTriShapes. Not all 3 levels need to have triangles, so if you want to create a "small details" shape that disappears < LOD2 you just fill the LOD2 with your NiTriShape and leave the others blank.

     Future Possibilities

  4. The FBX format supports LOD levels. If I were to write an FBX importer/exporter, I could theoretically support BSLODTriShapes without needing the above two way conversion process.

[ttl269]

@jonwd7 Your muli-part solution seems good as it is universal and within nif and Nifskope.

NifSkope should be able to convert a BSLODTriShape to 3 NiTriShapes. It should append ":LOD0", ":LOD1", and ":LOD2" to each level's new NiTriShape.

I think that it would be good if Nifskope can convert BSLODTriShape into NiNode containing three NiTriShapes with above mentioned append to their names. And vice versa: Nifskope should be able to create BSLODTriShape only from NiNode containing NiTriShape blocks (max. three) and only from those having their name ending with ":LOD0", ":LOD1", ":LOD2". So, when user will want to have for example only LOD0 and LOD2 in BSLODTriShape, he would create (or get it from 3D soft exported with nif export plug-in) NiNode with only two NiTriShapes with appropriate append in names.

Because it is easy to create NiNode like structure of meshes with names in model in 3D soft (at least in Blender), so when the model is exported to nif, user get needed structure of NiNode->NiTriShapes in it.