I am trying to make a rig in Blender of famous Squash&Stretch Bouncing Ball. This is the old school rig to start practising animation. I suppose everyone knows AnimationMenor videos
But as this should be piece of cake I am just hitting my head by keyboard. In Blender it is quite tricky and really hard.
The rig and controls should enable this:
Move and Rotate the ball. Ball should not be moved directly but by handle!
Squash and Stretch BUT INDEPENDENTLY on ball rotation. See pictures hereunder. Seems unsolvable in Blender because Stretch to constraint cannot influence the target in relative space.
Ball should correctly roll in when moved. This possibility may be possible to switch off when animator for example throw (i.e. move through air) the ball forward but rotate it independently (do you play football
it should be possible to move the centre of Squash and Stretch (in real life the ball stretches one way when flying in air and other way when hits the ground)
all animation keys should be on rig or other controls not on the mesh itself (as this is the standard for animation)
I would welcome any help. Maybe new python constraints (SVN) might help. But at this moment I am really frustrated and quite disappointed Blender is not ready and able to set up such a rig which is āmustā for animation practising and training
This was also my first tip. But did not succeeded. I am using SVN build.
My WIP so war was:
make UV spehre, assign material to see clearly orientation of this Ball
make a lattice (LatticeDeform)
UV sphere is deformed by LattticeDefrom
make a second lattice (LatticeDriver)
make an empty (whatever) as a Stertch to constraint driver (StretcDriver)
LatticeDriver is Stretch to constraint to StretchDriver empty
to each vertex of LatticeDriver vertex parent Empties
use Emtpies (that are vertex parented to LatticeDriver as Hooks for each vertices of LatticeDeform
But Ball rotation is not independent concerning it rotation even though it should. This also does not provide solution to move SquashStretch centre relating to the ball (you need it to be on the side of the ball when hitting the ground but in the centre of the ball when flying through the air).
Thank you for any information regarding your tests.
WARNING: the file is 4mb, and will only work in SVN versions
This is just an initial rig. There are still some problems to resolve (i.e. auto-rotate feature isnāt working yet, there isnāt any way to control which way āsquashes/stretchesā more), bone shapes could be added, and the controls could be made more intuitive/simpler.
I have download it and just tested it for couple of minutes. There are some same problems that I was also facing with my approach described hereabove.
I am quite pleased that it is just you Aligorith who finds it interesting to participate in this āultimate entry level animator rigā
Stretch to script seems better approach then standard stretch constraint. But it seems quite tricky to which parameters of the ball it should be mapper. May be it would be better to map influence to the lattice. Because lattice in object mode should be transferable (i.e. rotated) without influencing the targeted object (ball).
In your rig is also one problem that I have already noticed in Blender earlier. When you rotate your Rotate bone it works OK along X.
But Y and Z rotates it other direction BUT WHAT IS STRANGE:
when I rotate Rotate bone using Y (green manipulator) it is in fact Z according to Transform manipulator panel (but Y according to header info line)
when I rotate Rotate bone using Z (blue manipulator) it is in fact Y according to Transform manipulator panel (but Z according to header info line)
I am not sure which parameter is right and evaluated by Constraints. (Maybe it has something common with gimble mode???)
Here I my actual WIP state as mentioned above - http://rapidshare.com/files/90632589/SSBouncingBall.blend
There should be activated Stretch to constraint Driven by StretchToDriver empty. But when it is activate it āruinsā the concept :-/ It deforms not only the Lattice cage but rotates also the ball. Also this does not enable future step which is to rotate StretchToDriver. Because the Stretch to constraint evaluates its world axes not local ones which is quite a pity.
I know very little about scripting which would definitely help. Maybe it would be enough to apply volume preserve script driven (scale of other two axes = 1/ square scale of third axe that is changing its scale) by lattice scaling?
JiriH: I have yet to figure out a way to do a decent squash&stretch ball rig in Blender. Itās ironic that we can do some fairly advanced rigs for Peach, but something as simple as a squash & stretch ball eludes me. Blender certainly doesnāt make it easy. In both XSI and Maya these things were (fairly) trivial.
But I can see the light at the end of the black tunnel.
Here is first pyConstranit that helps you to move the pivot - http://www.alienhelpdesk.com/python_scripts/pivot_constraint . I did not tried and test it but this may influence the centre of squashing. To rotate squash/stretch axes independently of ball rotation is still tricky. Standard Stretch to constraint also involves some rotation possibilities and influences to the constrained object which is pity.
Rolling of the ball can be solved by another pyConstraint (or even python expression for IPO). We just need to use ball axes and use expression y=2pir (for y axe) ā¦ same for other axes. This pyConstraint may be āmutedā by influence button.
I hope that there soon may be quite good pyConstraint repository for such things. I hope python coders will be enthusiastic to write dozens of useful pyConstraint as this superb new possibility is finally implemented in next release.
Thank you very much. I know this rig. But it does not have all the features mentioned in the beginning which is clear when you was not able to use some needed python constraints.
Hmmā¦ what exactly is the situation youāre trying to achieve. The rig I posted does SCALING INDEPENDENT OF ROTATION (i.e. ball can still roll, but squashing is not done along the ballās local axes, but the āglobalā axes). Isnāt that what you required (are still looking for)? If not, how? Examples please.
Thank you for your interest Aligorith. I am playing with your test rig a lot. My problems mentioned hereunder were partially solved by using new build from Graphicall.
But there are still some bugs I would like to solve. I am quite busy toady in my job so have just a little time to play with Blender. I will definitely report on any progress.
So big thank for your blend file and script.
I am giving up. After two weeks and hours of testing I have not succeed to make a rig in matter which would fulfil the conditions hereabove. As I know practically nothing about python I am not able to code which probably may help (new pyconstratints).
I will probably download trial version of XSI as Cessen (Nathan) mentioned hereabove to practice such animation beginner S&S ball lessons.
I donāt know if you guys are still interested in this issue but I am also looking into rigging a S&S ball lately and I must say that the bones-only based approches that looked like they should work have all failed yet.
One issue I find particularly puzzling is the meaning of Local vs Global spaces. I read Ton explanation about those spaces and I think I get them but when I try to use them in constraints, they donāt give the expected results. I tried all 16 possible source and destination combinations.
What Iām trying to do does work when I position the bones manually in a pose but it does not work anymore when the same bone is positioned from a copy rotation constraint. Here is my idea and approach:
In a parent / child bone hierarchy, if the parent bone is scaled on one single axis, the child is also scaled but along the parentās local space. That is exactly what I want. And no matter how I pose (rotate) the child bone, it always gets scaled along the parentās local space. But because I want the child bone rotation to be independent from the parent rotation, I constraint the child bone with a copy rotation to another independent bone. And when I add this constraint, the child bone scaling stop being along the parentās space. It just copy the parent scaling along its own local space.
Is there any solution to this issue? If my explanation is confusing, I can prepare and post an illustration. If anyone can shed light as to the meaning of āLocalā, āLocal with Parentā, āPoseā, and āGlobalā for both target and source I would greatly appreciate. Would that space conversion be usefull for what Iām trying to accomplish or is that useless in that circumstance?
Iāve also been looking at the script constraint possible solution. Thanks Aligorith for the script. That is a great start. Obviously, the keep volume part is a must have.
BTW, the equation to preserve volume should be ā1 / math.sqrt(math.fabs( obsca.y ))ā. Without the sqrt, the volume is not preserved.
PS. Sorry for resurecting this old thread but since you were already intrinsically interested in solving this issue, I thought I might join in.
From the sounds of things, youāll need to write a pyconstraint for this. Iām guessing that what needs to happen is that the order that transforms are applied, needs to be tweaked a bit for your purposes.
What currently happens is:
scale * rotation * location
What you want is:
rotation * scale * location
It turns out that this is not enough. It seems tha what I really need to do it is transform the ownerās bone into the target bone space, apply the scale transformation and then retransform the ownerās bone back into its own space. That is why it works when the bone is simply a child of the parent but it does not work otherwise. When the bone is the child, the transformations are applied into the parentā space. But if the parent to child trnasformation relationship is broken by any means, then this does not work anymore.
I will work some more on figuring the chain of tranformation to accomplish that but if someone, who eats transformation for breakfast, can figure that in a blink, I would appreciate some help.
After some break I have given it another try. May be there be even two quite acceptable solutions (rigs). Some details have to be solved still. First test may be posted after final release of Blender 2.46.
There is a strange switch of axis that I donāt understand. I keep having the same issue as Aligorith ball which rotates around a diferent axis than the rotation bone. I get that all the place and I think I would need to analyze the matrices in the debugger to figure a solution. But that would take me way off my goal and it is not worth all that time to solve the squash and stretch ball and I need to get back to my main project. So I decided to leave that problem and move on.
