About this Document...
Create a Quadruped (Horse)
Editing the Avastar Skeleton into a Quadruped Skeleton
What does Avastar provide?
Avastar basically supports the creation of animatable Models (Avatars&attachments) and the creation of animations. Therefore the tool adds various functions and user interface elements to Blender.
The full functionality of Avastar can be a bit overwhelming on first sight. You should be prepared to spend some time and patience to get it all working nicely for your projects.
What does this Document provide?
This document is a quick start into Armature Editing. In this section you will learn how to prepare Avastar for your work on non human meshes. We use a Horse as the modelling example.
However this article only scratches the surface of Avastar’s feature set, so there is a lot more to detect and we invite you to make your own experiences as well.
We expect that you have basic knowledge about Blender.
Hello and Welcome back,
This is an overview about the rigging of quadruped characters
for the Second Life environment.
I will give you a step-by-step introduction
into the creation of a basic horse-skeleton
I show you in great detail how to rig the model
i will adjust some of the weights by using the weight-paint tools
and finally i will create a very simple static pose
for the export to Second Life.
so lets open Blender with the model of a horse,
Note that this model is also distributed within the 4th lesson of our online course: non-human-rigging,
and when you have purchased the course then you are also free to use the model,
even within your own commercial projects.
ok, lets proceed by adding a new Avastar character into the scene.
so to begin i recommend to move the horse to a separate layer.
You can do this by first selecting the model,
then pressing the “m” key
and select in which layer the horse shall become visible.
Note that you later can enable or disable the visibility
of multiple layers by pressing the SHIFT key
and then click the corresponding layer icons.
ok, our next task will be to change the default character’s skeleton into a horse skeleton.
Here we have to take care about some restrictions
which are imposed by the Second life animation system.
The most important point is We can not
use additional bones to improve the skeleton
so whatever we create here
it always has to use the second Life Basis bones or the Collision Volume Bones,
and nothing else.
But Luckily Avastar has been designed with these restrictions in mind.
Lets select the armature in Pose mode,
then go to the tool shelf
open the Avastar Tab
and locate the rigging panel.
Here you find the bone visibility section.
This section is currently collapsed.
You can expand it by hitting the small plus sign on the left-side.
Also by default we see a set of green control bones,
These bones are mainly used to create poses
In addition to the control bones
we also have the set of blue Second Life Bones.
These are the bones which later are needed to define the weight-maps for deforming the meshes.
The blue bones and the green bones are tightly related to each other,
that is: for each blue bone
we have a corresponding green counterpart.
By default only the green control bones can be moved and rotated.
However, each blue bone always follows the movements of its green counterpart.
Later we will see that Avastar provides tools
for the automatic adjustment of the Second Life bones.
Hence we actually do not need
to bother with these bones at all.
Instead of that lets forget the blue bones for now
and only edit the green control bones.
So, Lets go ahead and prepare the Avastar-character.
First of all we delete the default Avastar-meshes,
because we really do not need them for the horse.
You can do this by navigating to the Object properties section
of the armature, and locate the Avastar Shape panel.
there use the function: delete Avastar meshes.
but of course you also can delete the meshes manually if you prefer.
Now lets enable the visibility of the Horse layer.
Furthermore, lets change the rig display as follows:
open the bone display panel
then from the available visibility presets select: edit.
This puts the armature into edit mode
and it enables the visibility of most of the editable bones.
However, since we do non human character modelling
we additionally have to enable another subset of bones:
the extra bones.
I can not tell it often enough, but you have to ensure
that you only modify the green control bones.
So, you should never touch the blue Second life Bones in edit mode.
And when i say never, then i really mean: never ever.
If you decide to not follow this advise
then i predict that you eventually will step into some serious pitfalls
when you begin to use Avastar’s and Blender’s animation tools.
Anyways, the edit preset takes care of all of this for you
and now we are finally ready to edit the skeleton.
for the begin let me move the eye target a bit closer.
we will take more care of this particular bone later when we prepare the head
Now select all visible bones by pressing the keyboard key “A”: twice.
and move the bones such that the horse’s hind legs
roughly match up with the legs of the human skeleton,
Now we change the human skeleton step by step into a horse skeleton.
Fortunately blender gives us a couple of tools
to make our life easier here.
First we can use the fact that the skeleton is symmetrical.
For example take a look at the hip joint.
When we enable x-mirror in the tool shelf Options tab
then editing a bone will automatically apply the mirrored operation
to the bone on the other side of the rig.
We also must be aware that some bones hide other bones,
as you can see for example on the ankle bone.
In this case you can always use the rubber band select,
by pressing ‘b’ on the keyboard,
and then span the selection region over the
joints or bones which you want to move.
finally, begin to move the bones into place.
Ok, we can now move upwards along the horse legs,
and adjust the bones as needed.
You see that i frequently switch between using the rubber band select
and right clicking on a joint.
When we get up to the Center Of Gravity bone,
then we have to take care a bit.
First let me select the entire upper part of the skeleton
and rotate it by about 90 degrees,.
Then lets take a closer look at the pelvis bone.
Actually you see 2 pelvis bones here,
created in opposite directions.
We will keep these bones as they are,
we only select the end joints of both bones,
and move them a bit towards the horse’s back.
This will later become relevant,
when we get to animation.
And lets make the Center Of Gravity bone bigger,
so that we can grab it easily
when we later animate the horse.
Now lets continue to adjust the upper part of the skeleton.
Again i frequently switch between grabbing a single joint,
and using the rubber-band-select,
when i want to select or deselect multiple joints or bones at the same time.
It is also good to adjust the eye target now.
Up till now i have only worked in side-view.
Now lets adjust the hind legs in back-view.
You can enable back view by first pressing the control key,
and then select front view on the number pad.
Now lets hide the hind legs for a moment,
so that we can concentrate on the front legs.
and lets switch to front-view.
Lets first adjust the eyes location.
It is a bit tricky to actually select a bone when it is in front of another bone.
So lets move out of front view for a moment
then select the eye bone
and get back to front view and adjust the eyes as needed
And then adjust the arm bones to the horse’s front legs.
Here, take care to also move the tails of the somewhat hidden collar-link bones.
Finally go back to side view
and adjust the bones from there as well.
finally, unhide the hind legs again,
and here it is Our horse skeleton is ready for usage.
well, no, not yet.
Until now we have only worked on the green animation bones.
Now it is time to take care again about the Blue Second Life bones.
So lets enable their visibility.
You see they are still arranged as a human skeleton,
so we now need to synchronize the blue bones with the edits of the green ones.
But don’t worry, we have a function for this.
Open the tool shelf and search for the deform bone constraints panel
and there click on: “snap Base to Rig”
Ok, on first sight it looks like the SL bones have been deleted,
but actually they only have been snapped to the control bones.
We can see much better what happens when we enter pose mode
oh. this doesn’t look as expected
we still see a big clutter even after we hide the SL Bones.
Well, we can disable the bone shapes so that the green control bones are drawn as octahedral.
And we can disable the display of the rotation limit guidelines.
Now we can see clearly that the green bones and the blue bones
are located at the same place, and all is well.
now lets move on to our final task,
namely rigging the horse and making an initial pose.
So lets go to object mode,
select the armature and the horse
and then lookup the Bind-to-Armature function
in the skinning panel of the tool shelf.
Note that we prepare a simple parenting without any weight copy,
Because actually we do not have any mesh
from where we could copy weights.
So lets use the keep-option here,
which does not touch the weight tables
during the parenting operation
Now it is time for weighting the model.
Select the horse,
open the tool shelf
and locate the rigging panel.
There, select the skin preset from the preset list.
This will put the horse into weight paint mode
and the armature into pose mode.
Furthermore the blue Second Life Base bones have been made visible
and the green control bones have been hidden.
and finally, the rotation constraints which tie the blue bones to the
green bones have been disabled. And all of this is done on purpose:
Remember that the blue Second Life Base bones are responsible
for the skeletal animation of the character. because of that
these bones are also named deform bones.
And the character mesh needs to cary the weighting tables for
these deform bones.
Hence we now have to leave the green animation control bones aside
and concentrate only on the blue bones instead.
so, lets now generate our initial weight maps as follows:
Begin by selecting all blue bones except the eye bones.
Please take care here because it is not so easy to see
if the eye bones are selected or not.
and now generate the weights by calling
Weights, Assign automatic from bones.
Blender will now preset the weights to reasonable initial values.
You can do a quick check by selecting individual bones
and examine how the weight maps are defined.
At the very end we have to check whether the weighting is good for our purposes.
When we now rotate the skeleton bones
then we can check for obvious weighting-errors,
and fix them as needed.
Well, when we bend the head
then we might see some issues with the vertices around the eyes.
There we sometimes find some unweighted vertices.
We can fix this quickly by weighting these vertices to the head bone.
For this purpose we open the Tools-tab within the tool shelf,
there we select the add brush,
preset the strength and the weight to a value of about 0.2,
and then carefully paint onto the visible spikes,
until they snap back to the head.
Now we can proceed to the next step,
namely animating our character.
However, since this tutorial is only about rigging,
lets just do a simple horse pose,
and verify that the rig works as expected.
but first and very important
lets select the pose preset from the rigging bone control panel.
If we forget to do this
then the green control bones remain decoupled from the blue bones,
which is certainly not what you want.
well, what you actually do want
is to disable the custom shapes, because they are optimized for human character animation.
And of course you want to enable x-ray mode, otherwise the control bones will be mostly hidden inside the model.
Finally, switch over to the armature
and create the pose in the same way as we created human poses in the past.
Please note that for some bones you will see
the original constraints no longer work well.
These bones can no longer be bended in a natural way.
This is due to the bone constraints, which still are
made for a human skeleton. If you want to know how
to adjust this in an optimal way,
then please check out our course
about non human character modelling.
In the meantime We can fix this issue quickly by disabling
the constraints of the currently selected bones,
from within the properties sidebar of the 3D-view.
Actually, we even can select all bones at once
and disable all constraints by one click.
Now lets go ahead and finish our simple pose.
And finally, when the pose is finished,
select all bones and then press the “i” key,
to create a new key frame.
You want to select locrot here.
And at the very end
go to the render properties section
and export the pose as a second life animation.
By now we can only create a static pose,
because we have defined just one single frame.
And we will define an infinite loop,
such that the horse keeps in that pose as long as
the pose is active.
when we finally upload the model to Second Life,
then we have to take care about 2 things.
first when you show weights in the previewer
you see the front legs get crossed.
This is so, because the previewer uses the default stand-pose for a human character.
But we have modified the orientation of the arms
when we bended them downwards in blender to create the front legs.
We will see in a moment that this issue will be solved
as soon as we upload our own stand pose.
The other point is: Whenever we have modified the Skeleton,
then we also must import joint positions.
When we forget to do that, then our mesh will deform in unpredictable ways
when it is worn.
So, lets now wear the mesh.
Of course we again see the crossed front legs.
So, lets also import the pose.
and we see as long as the pose plays,
the front legs do what they are supposed to do.
So, that’s all that i wanted to show you in this tutorial.
But we are not yet at the end of all possibilities.
That is: You can also configure Avastar’s I-K-Rig for your horse, dog, fish,
or for any other non human shapes.
If you want to learn more about how to get the most out
of Avastar, then please consider to purchase our advanced
tutorial “non-human-rigging” for Second Life.
The advanced tutorial contains an extended version
of this video tutorial with many
more tips and tricks,
a detailed description about customizing the Rig
and a commercially usable blend file of this horse model.
Thank you for watching this video
and have a nice day.