Avastar User Interface (Mesh)

By default Avastar applies all mesh changing Modifiers except the Armature Modifiers to the exported meshes. However, some modifiers have 2 sets of options, one option set is for rendering, the other option set is for the Viewport. We provide 3 options here:

• Apply according to the View Settings (the 3D Preview settings)
• Apply according to the Render Settings (the settings for Blender’s own Renderer)
• Don’t apply modifiers and only export the base mesh
  

The View settings  will be applied by default. These settings are very closely related to the Blender Render System. In most cases you can actually just use the defaults. We will get back to this when we talk about how to use (or not use) Modifiers.

Armature Modifiers define a relation between your mesh and your Skeleton (Armature). You find the Armature modifier in the Modifer Stack (see image). Armature modifiers are always defined for the mesh. Armatures them self have no Armature modifier.

We will get to armature Modifiers in the “Create an Attachment” tutorial.

You can export images along with your models. In that case the images will be stored as extrafiles and a reference is added to the Collada file. The SL Importer knows how to read and import these images for static meshes.
Note: But for rigged meshes the images are not recognized.

• UV Textures & Material Textures: Blender supports Material based textures and UV textures (which are directly assigned to polygons). Normally you want to export only the UV textures. In rare cases it is more desirable to export the material based textures instead. But beware, Blender does not export the render results, but only the source images!
• Image Type:  The image format is typically predefined in the Blender Render settings.  However we found it convenient to provide an immediate setting in the Exporter. By default the image type will be applied ONLY to generated images.
• Use ‘Image format’ for all images: If this option is set, then Blender will use the selected image format for all exported images. If the option is disabled, then only the generated images will be affected.

• Use RGBA: Blender can export the Alpha channel for images. Normally this is controlled in the render settings where you can specify to use either RGB or RGBA for image exports. If the currently selected export format supports Alpha then enabling  RGBA here will export images with Alpha channel even if the render settings are set to RGB and vice versa.

Hint: You may want to NOT use RGBA because of the Alpha glitch. However this is not a general advice. There are many situations where using Alpha images is even recommended (for example when you want to create an Alpha mask).
Hint: If the format of the exported image(es) does not support an Alpha channel then the “Use RGBA” option is simply ignored.

The Advanced Options are related to some special issues. You should normally keep the options set as they are. This ensures your exports are well suited for SL. However in some situations you will have to get back here and set the options according to the descriptions below:

Apply Armature Scale: If you have scaled your Armature in Object Mode for making a tiny or a giant you should not apply the scale to the armature because then the entire Avastar Animation system may no longer work (details need to be documented). But the Object Scale must be applied when you export the mesh.

Otherwise your scaling will not be recognized in your target online world and the giant shrinks back (or the tiny grows back) to normal size. The Applay Armature Scale option ensures that the Object scale is applied in the exported Armature.

Apply Rotation & Scale: If you have Scaled or rotated your Objects in Object Mode then this Scale&Rotation should be applied to all objects of an export to avoid unexpected scaling and rotation issues within the target system. However this is all so often simply forgotten and sometimes even unknown.

Hence we have added an automatic apply Rotation&Scale to the exporter. This setting does not affect the original objects.

Weld Edge Normals: When two separate objects share a boundary line, then you typically see a boundary seam in the object texture. This happens because the vertex normals differ even if the adjacent objects share the exact same vertex locations.

This option recalculates the vertex normals at the adjacent boundaries of the selected objects.

Weld to all visible: Sometimes you want to only export one part but still want the vertex normals be fixed.

This option lets the exporter take all visible objects into account when calculating the vertex normals at object boundaries.

Include Deformer Shape: Some virtual worlds support the Mesh deformer which was originally developed for usage in Second Life.

When this option is enabled, then an additional xml file is created that can be used as reference shape if the Importer supports this feature (currently used with OpenSim)

bone bug fix: We have found that some online worlds have serious issues with modified Joint offsets for Collision volumes and Attachments(1). Hence we suppress the export of joint offsets for collision volumes and attachment bones by default.(1): The technical details are related to the SL Importer’s option With Joint Positions The Skeleton can be modified (in edit mode) to create other rest poses than the default rest pose (T-Pose) When you do that, you actually move the Joint Offsets away from their default locations. And you will later have to set “with Joint Offset” during import in order to get your modified skeleton uploaded.

However this works only for the SL Basic bones (the mBones) All other Bones have various issues with Joint Offsets. The Collision Volumes do not work at all when you try to import them with Joint Offsets. We consider this an SL Bug. So we have added the Bone Bug Fix option. This option should only be disabled for experimental purposes! Handle with Care. You likely break the animation system.

These vertices are not assigned to any of the Deforming Bones (unweighted) or assigned with a total weight of 0 to one or more Deforming groups (zero weighted). These vertices only move along with the movements of the mPelvis Bone.

When you pose any other bone in Blender then this appears like the unweighted vertices are simply “glued” to their RestPose Location (See image)

 

Note: Avastar does not allow to export a mesh with zero-weighted or  unweighted vertices. The original reason for this was that the SL Importer would not accept these meshes either.
But nowadays the SL Importer will accept the mesh for import. However unweighted vertices will disappear when you wear the mesh, while zero-weighted vertices behave like in Blender

In Blender you can assign as may weights as you like to one single vertex. But in SL (and OpenSim as well) the maximum number of weights per vertex is limited to 4.

The Avastar Exporter will automatically reduce the number of weights per vertex. It simply removes the weights with the smallest weight values until the number of weights is 4 for the vertex.

Note: In SL it is unclear what exactly will happen. We do not know if the first 4 weights are preserved or the 4 weights with the highest values are preserved.

Duplicate vertices are 2 or more verts which occupy the same location in 3D space. While this is not necessarily an error, and sometimes it is actually wanted (for example when you use an efge-split modifer),  it is still important to avoid duplicate verts wherever they appear unintentionally to avoid potential texturing issues and weighting problems.

Note: In SL there is no special signature for unwanted duplicates, so you have to check this on purpose if you want to avoid them.

During parenting a mesh to an Avastar rig you can enable an initial Weight copy from all visible siblings to all bones of the parented mesh. In the image on the right you see the armature (yellow) and the shirt(semi transparent) selected. Initial weight copy will project the weights of the upper body into the weights of the shirt. For more detailed information see the Reference guide
Binding(Assign to Armature).

Avastar supports 2 different skinning patterns for animating an SL mesh character:

• Via weighting the mBones
  (also named Classic Weighting)
• Via weighting the cBones
  (also named Fitted Mesh Weighting).

Avastar can pre configure a Mesh to use either of the weighting patterns. For details read the Skinning section.

While working on the weights of a mesh in Weight Paint mode you can do a weight copy on a bone by bone base. The details are described in the weight copy tool reference below.

Note: The Selector in the Mirror Opposite Bones button is new with Avastar-1.3

If you want to copy from another bone, then you must ensure that you have selected exactly 2 bones, where the source bone must be selected first while the target bone is SHIFT Selected second (so the target bone becomes the active bone!)

Note: The target bone’s weights will be entirely replaced by the weights from the source bone, not added or merged!

If you want to mirror copy then you only have to select the target bone(s). You can select a set of bones. Avastar will perform the mirror function on each selected bone.

 

New in Avastar-1.3: You now can specify if your copy shall use Topology mirror or Vertex Mirror. Please be aware that topology mirror can only be used when the mesh is not symmetric! For perfect symmetric meshes you will always use Vertex Mirror.

A common pitfall with Weight Copy happens when your mesh is slightly asymmetric. on the next image you see an example:

The boots look pretty much equal, so you have the impression that a weight copy should be no big deal. But actually i have moved the left boot slightly out of symmetry, so all vertices have a small offset from perfect symmetry. And you can not see this slight asymmetry by just looking at it.

Lets assume you have carefully weighted the left boot and now you want to mirror copy the weights from the left ankle to the right ankle.

So you will select the right ankle bone, and then perform a Mirror from Opposite Bone. But you end up with the weights not mirrored. In the image you see the weights are not copied to the right ankle as expected, but the weights remain on the original vertices.

Whenever you see this happen you can be sure that your mesh is not exactly symmetric. In that case you can try a topology mirror copy, but unluckily this has its own pitfalls as well…

So lets try to do a mirror copy with topology mirroring enabled (select Topology in the selector right to the Bone Mirror Copy Butto). In my case i ended up with a very strange result as you can see in the next image.

The problem with topology mirroring is that the used function needs a more complex mesh to identify the mirrored vertices. I have not fully understood how it works, but apparently it does not work for low polygon meshes, hence Topology mirroring is in general not suitable for game engine development.

Each classic mBone is related to a corresponding fitted mesh cBone. Hence when you select any of the Deform bones the tool knows which is the counterpart bone according to the table below.

Each time when you call the tool, the weights of the selected Bone(s) will be swapped with the weights of their corresponding counterpart.

This is obvious: The weight groups of all selected bones will be reset (made empty). You may want to do that when you decide to restart a bone weighting from the beginning.

If you want to copy weights from other meshes (weight sources) to a mesh (weight target), then all source meshes and the target mesh must be siblings of the same armature. (all meshes must be attached to the same armature). All currently selected bones will become Copy targets in that case.

Note: Only visible weight sources are taken into account. Hence at least one weight source (mesh) must be visible.

Note: If you want to do a full weight Copy, then you only need to select all SL Bones (the blue ones) as seen in the image to the right.

Note: Custom meshes can also be used as Sources for a Weight Copy, provided they are siblings of the active Mesh!

Note: the topology of the source meshes and the target mesh may be different!

Easy Fix (recommended)

• Select the Mesh
• Object -> Parent -> Clear and Keep Transformation
• Object -> Apply -> Rotation and Scale

Advanced Fix (not recommended)

• Select the parent of the Mesh
• Apply Scale and Rotation
• Do the same for the Parent’s parent and so on…

You prepare the binding step as follows: First you align your new mesh attachment as good as possible to the Avastar character. Then you select both the armature and the new mesh attachment:

• Go to Object mode
• Select the attachment with RMB. If you want to bind multiple new attachment at once, select all of them now (order does not matter).
• SHIFT RMB select the Avastar Armature.

Now you have selected the Rig and all mesh attachment which shall be bound to the Armature.

In principle this option does the equivalent of the following procedure:

1. The current pose (“mesh pose”) is made the armature’s default pose.
2. The mesh is parented to the new default pose
3. The pose is set to the actual T-Pose (and the mesh gets bent into T-Pose)
4. The mesh is frozen (pose applied and mesh unbound from the armature)
5. The armature’s default pose is set back to T-Pose
6. The mesh is parented to T-Pose.
7. When now the armature is posed into the original “mesh pose” then the mesh looks exactly like it looked when it was not yet parented.

Avastar does not step through the above process, but instead calculates the needed modifications and applies them directly to the mesh, then parents to the Avastar Rest pose (T-Pose).

Note: Since Avastar is modifying your mesh directly, you should use this tool with caution.