EnigmA Amiga Run 1998 July/EnigmA AMIGA RUN 29 (1998)(G.R. Edizioni)(IT)[!][issue 1998-07 & 08].iso/recent/iib122.lha/IIB/Threads/Bones_Basics

Text File | 1998-04-05 | 16KB | 320 lines

This is an additional to the Bones for newbies Thread.
I make it as an own Record for the length of this file.

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Date:         Mon, 30 Mar 1998 00:04:01 EST
From: Amayyama <[e-mail]>
Subject:      [IML] IFW: Bones Answer (long)

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>When I load this object into the Stage editor however really wierd things
>happen.  As the tube rotates from left to right, the end of it scales way
down
>as it rotates.   It always ends up at the right state but the way it gets
>there is all wrong.  I have created three different tubes trying shape vs
>grouping and always the same results.
>A wierd shrinking scaling phenomonon.


>Andrew May

Hi Andrew

Clae here

Check your States

If your going from a States Shape/Grouping to Shape/Grouping it will do what
you described. It wont show up in the Detail Ed but in the Stage

Do this and see

make a DEFAULT State of Shape/Grouping
Then a REST State of just Grouping
the States you'll be moving from and to with the 'Grouping' option only.

Clae F Tanett
[e-mail]

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Thats it Clae.  Thanks a bunch.  Now I can get on with my dream character
animation project.

This list is great.  Some day I will have to figure a way to pay you all back!

Andrew

John

I just read your post .  Sorry for the lag time, I am on digest mode.  Your
post is accurate as far as I can tell.  So if you want bulging muscles you may
have to use more states to get shape/grouping to work.  If you want lots of
good motion with few states use only grouping.

PS . I am including a list of to do's and not to do's concerning bones.  It
may help someone else.  I can't remember where I got it though so if its yours
please take the credit for it.  In the back of my mind it seems like it came
from Tim Wilson of Crestline Models.

1. Design your Geometry and Bones to work together. You can't do either your
modeling or your boning totally independently of one another. You will have to
go back and forth between the two, until you come up with an optimum design
for the geometry, and figure out the appropriate layout of the bones. Drawings
will help, especially to locate articulation points in the model, and will
make the job of building the skeleton easier. </UL>

2. Geometry should be built to accommodate interpolation around a joint. It's
not necessary to use regular cross-sections at joints but this may help you
when defining the Big and Small Bone Subgroups. </UL>

3. Design your geometry to look as good as possibly through the widest range
of motion. </UL>

4. If possible Bone the object with the limbs bent halfway through there
normal range of motion. For example model your knee or elbow slightly bent
rather than straight, and bone them that way. This way when you bend the joint
it will look acceptable through a wider range of motion.</UL>

5. If it's too difficult to bone the limbs with them partially bent, then
design the geometry the way you think you can bone the figure most easily or
logically. You may find it easier if the limbs are aligned at more logical
angles. For example, if you model a hand with the fingers bent in a natural
position you may find it very difficult to get the bones set up right. The
fingers can be more easily boned if they are aligned at more regular angles to
the world axes. Then once they are boned you can bend the fingers into a more
relaxed shape. Realize however that by designing your geometry with the limbs
set at regular angles you may sacrifice some of the aesthetics of the model.
</UL>

6. Put in enough points or cross-sections at the joints so when the limb is
bent it won't start to look faceted. If you need to increase the detail, try
Fracturing the area around the joint, and then running the new Smoothing Tool
in 4.0 over it.</UL>

7. Realize that polygon geometry is not infinitely flexible, and that the
range of movement in joints is going to be somewhat limited. Even though you
may try to design your geometry for the widest possible range of motion as
described above, when you bend the  limbs into extreme positions, it will be
hard to avoid ``crimping''. However, remember that your design does not have
to be 100% perfect, because you can tweak the geometry in some poses and use a
little morphing in combination with the bone deformation to get the bent joint
to look better. </UL>

8. Once you've got your basic modeling done, layout your bones in the
positions where you want them, before you begin to define the Bones Subgroups.
Bones are good not just for limb joints but also spinal, tail and neck
articulations especially if these are modelled with cross-sections.</UL>

9. All boned objects need at least 2 Bones. At the bare minimum, you need one
bone to anchor the basic geometry parented to a second bone where you want the
object to bend.</UL>

10. A BONE is simply a naked AXIS linked to your geometry.</UL>

11. When possible, each Bone should have its Z axis pointed toward the child
below it in the hierarchy. This is more of a guideline than a rule. Obviously
if you are branching out from a back bone into two arms, you can't have the
parent back bone pointing towards the next articulation in the spine, AND the
shoulder joints as well. </UL>

12. Group Bones Serially. Do not group all of the bones to a single parent
axis. You must go down through the hierarchy progressively grouping each child
object to its parent. If you use the basic GROUP command, every parent and
child pair must be grouped individually. PICK THE PARENT OBJECT FIRST such as
the Elbow, then Multi-Pick the child object such as the Wrist, and execute the
Group command. You cannot simply PICK ALL the bones and then GROUP them at
once. Serial grouping establishes the hierarchy. You know the old song... the
hip joint is connected to the knee joint, which is connected to the foot
joint. The shoulder joint is connected it to the elbow, which is connected to
the wrist, etc. </UL>

13. The new CASCADE GROUP command in 4.0 States menu will be a tremendous help
on this. It's more sophisticated than the old GROUP command. It will
automatically group objects serially, in the order they've been selected. For
example, if you select the Chest, Shoulder, Upper Arm, Forearm, and Hand, in
that order, and then execute the Cascade Group command the objects will all be
serially linked in a chain, rather than all grouped to the Chest. This is just
what you need when setting up hierarchies of bones, particularly vertebral
articulations. </UL>

14. Once your skeleton is built, Group the skeleton to your geometry by
Picking your GEOMETRY FIRST and then the master parent bone in your skeleton,
and then performing the GROUP command. This will make the Geometry the main
parent of everything. The Geometry's axis is not used to manipulate any part
of the figure. It is used to translate and rotate the WHOLE figure through
space in the Stage. So you might want to position the Geometry's axis
strategically for that purpose, either near the feet or in the middle of the
Pelvis or Center of Gravity.</UL>

15. The geometry must always be the master parent in the hierarchy, when using
bones. </UL>

16. Movement of the master parent cannot be incorporated into a State, so you
will need to use the first bone in the hierarchy  to get the whole geometry to
move as part of a State. This first bone should be placed strategically for
manipulating the whole model, in the center of the figure's pelvis for
example, or as anchor on the ground.</UL>

17. The first bone in the hierarchy must have ALL faces in the geometry
selected for both its Big and Small Subgroups. Then when you move the bone the
whole geometry will follow it. (You can of course also move your whole figure
in the Stage by tweening position. Sometimes you may wish to do both. For
example, you might want to have an up and down motion as part of the States,
but a forward motion as a change of Position in the Stage.)</UL>

18. Assign a Big and Small Subgroup to each Bone. This  may seem obvious, but
each bone MUST have subgroups defined otherwise the model will not work AT
ALL.</UL>

19. Every Bone linked to the geometry must have Big and Small Bone Subgroups
defined. </UL>

20. The Small Bone Subgroup represents the area of the limb's geometry that
you want to rotate TOTALLY when the joint is moved. (Just a note of
clarification. What the term `Small Bone Subgroup' ACTUALLY  means is the
*small subgroup*  for the bone, NOT, I REPEAT, NOT the *subgroup* for the
small bone....   There are no *small* and *big* bones...... What you are
defining is a *small subgroup* and a *big subgroup*, to GO WITH each
particular bone.)</UL>

21. The Big Bone Subgroup includes the area of the limb that you want to
rotate totally, PLUS the area of geometry that will bend when the joint is
moved.</UL>

22. Just so you know, the Big Bone Subgroup MINUS the Small Bone Subgroup is
the area where the geometry will bend, stretch or interpolate around the
joint. Your bone should be roughly centered inside this area of
interpolation.</UL>

23. Knowing how large to make the bending area for a particular joint is
something that comes through experimentation. A good rule of thumb is to make
the bending area roughly as long as the object is wide. But this does not
apply in all cases.</UL>

24. Never make a Small Subgroup BIGGER than the Big Subgroup though. Imagine
will choke on this.</UL>

25. Assigning Subgroups to Bones can be done in two different ways. In 3.0,
you must MAKE the SUBGROUPS first in PICK FACE mode, then pick your bone and
use the BONES SUBGRPS command in the STATES menu to assign them to the Bones.
</UL>

26. In 4.0, you can use `Quick Bones' to assign the Subgroups. Again when you
go into PICK FACE mode, outline your Subgroups and then in the FUNCTIONS menu
select either the MAKE/SML BONE SUBGRP, or MAKE/BIG BONE SUBGRP command, and
then simply click the mouse on the axis you want the subgroups assigned to. It
might be advisable to create Gadgets for these commands. It speeds things up
considerably.</UL>

27. (3.1 USERS ONLY- DANGER ALERT!  If you are using Quick Bones in Version
3.1 the MAKE SML BONE SUBGRP and MAKE BIG BONE SUBGRP commands' names are
reversed [at least in my copy they are]. You can rectify this by assigning
GADGETS to both commands and simply reversing the names.)</UL>

28. If you put the first bone in your hierarchy at the same position as the
geometry's axis, you may have trouble selecting it with Quick Bones. In this
case just make a Subgroup for all the faces in the geometry, and assign them
to the Bone using the BONES SUBGRPS requestor.</UL>

29. If you are using 3.0 name your Bones Subgroups logically when you create
them, otherwise you won't remember which subgroup goes with which bone; And
also so they'll be easy to sort out later, if you have to make changes. If you
are using the Quick Bones in 4.0, the naming of Subgroups will be taken care
of automatically, and will be derived from the Bone's name. So make sure to
name your Bones logically, before you begin making the Subgroups</UL>

30. Check to see if your Bone subgroups are correctly assigned. Once you've
made your assignments you can check to see if they're set up right by going
into the STATES pull down menu and selecting BONES SUBGRPS.  See what names
are shown for the BIG SUBGROUP and the SMALL SUBGROUP. Then hit BROWSE and
locate the names and compare the number of faces for each. Obviously the BIG
subgroup should have more faces than the SMALL subgroup. In the final
analysis, it doesn't really make any difference what method you use to assign
the bones. The only thing that matters is what's shown in the BONES SUBGRPS
requestor.</UL>

31. The CHECK OBJECT command will also tell you if there are any errors in the
basic structure of the Bones and Subgroups. So be sure to perform this command
when you're finished.</UL>

32. Don't create your Default State until you've set up all the bones and done
the subgroup assignments.</UL>

33. The DEFAULT STATE MUST HAVE SHAPE AND GROUPING STATES DEFINED to lock the
geometry to the orientation of the bones. The Properties are optional but in
most cases probably should also be selected.</UL>

34. Lock your textures to the DEFAULT State. Please note that Locked Altitude
Brushes do not work correctly with Boned objects in Imagine versions 3.0 -
3.11.</UL>

35. You may find that the Default State you created for  boning is not
suitable for applying Brushes (and Textures which have a regular pattern). For
example you might want the limbs to be straight instead of bent so you can
apply a cylindrical map to them.  If this is the case, then straighten out the
limbs and CREATE a new STATE, and lock your textures to it instead. </UL>

36. Create new poses for your figure by ROTATING joints in PICK GROUP mode
around their LOCAL axes. This will maintain the hierarchical relationships and
allow you to create more realistic poses. </UL>

37. The order in which bone deformations are applied to the geometry is the
the order objects are listed in the FIND REQUESTOR, from parent down to child.
The child bones lowest in the hierarchy are applied last. </UL>

38. Be sure to SAVE your whole group after creating new States in the Detail
Editor, otherwise the object file will not be updated with the new States.
Select the master parent in Pick Group mode, and then SAVE it.</UL>

39. Bone States other than the Default, only need GROUPING defined. The
exception is when the geometry is also deformed with morphing to cleanup a
joint in an odd position, or change a facial expression. Then you would need
SHAPE defined as well.</UL>

40. Although you can define States at any level in the hierarchy, the only
States you can call up in the Action editor are the ones defined for the
master parent in the hierarchy. You may for example want to make a bunch of
different arm poses,  and store theses States just for the Shoulder and its
children.  But you will need to make these part of an overall body State,
before they can be used in animation in the Stage. When you have a pose
constructed that you want to include in your animation, select the master
parent in Pick Group mode, and then CREATE your State.</UL>

41. There are two ways to see if the geometry is deforming correctly after
you've built a pose with bones. First you can simply pick the master parent
axis in Pick Group mode, and then use BONES UPDATE. (Please Note: You don't
need to do a BONES UPDATE each time you create a new state with Bones. It's
there mainly to check the deformation of the geometry. However you won't hurt
anything by doing it.) The other way to see the deformation is after you've
created a State, you can just SET TO it again, and you will now see the
geometry deformed.</UL>

42. Clean up problems with the geometry around joints using a SHAPE State.
This is one of the important tricks in getting bones to work well. Sometimes
when you bend a limb into an extreme posture the geometry just won't bend
correctly around the joint. You will usually see these problems after you
perform BONES UPDATE or SET TO a States that's already been created. Just move
the few points that are out of wack, and add a SHAPE state to this pose, in
addition to the GROUPING. The SHAPE State can be added by going into INFO for
that State. Then when you stage animation that uses this pose, morphing will
correct problems with the geometry. (The new Smoothing Tool in 4.0 may be
helpful for this. You should be able to select a problem area where the points
are out of wack and then just run this tool over it to smooth it out.)</UL>

43. NEVER use a DEFAULT state in your animation, because it will not
interpolate with other key states. Default states should be reserved for
creating a base shape for Locked textures and brushes. Get into the habit of
making a duplicate copy of the Default as your first NEW state, so you can
include that pose in you animation when needed.</UL>

44. To animate a boned figure, set up a series of keyframes for it in the
Action editor, by ADDING new bars to the ACTOR channel, and calling up the
various poses with the STATES BROWSE menu in the ACTOR requestor.</UL>

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