bones constraint ?

[createo]

Hello,
I am in the process of testing bone stresses with AM.

I do fairly empirical tests and it lacks efficiency in some cases because I do not really understand what the constraints correspond to in terms of parent / child links.

Is there a list, or a table summarizing the context of action of each constraint?

It would be much more efficient for me!

thank you in advance

[robcat2075]

Hi Teo,

Do you have the Technical Reference?

You can download TECHREF.pdf at ftp://ftp.hash.com/pub/docs/

It begins discussing constraints at pg. 140  and describes each individually except the recently added "Group" constraint and "Bullet" constraints.

Aim At, Translate To, Orient Like and Kinematic are the four important ones. They are used more than all the others combined, a hundred times over. The others are great to have but those four do most of the work.

I have never used "Aim Roll Like Two"

If you still have questions, ask.

[createo]

Ah yes !!
I hadn't been that far. It must be said that for me, so much written English is a bit painful to read
thank you

[robcat2075]

Je regrette il ñ'y a pas une édition Français!

 

Does this make any sense? I copied a paragraph from the PDF into Google Translate.

I don't think it understands the CG meaning of "translate to" (to move something from one point to another point) but it looks serviceable otherwise.

 

 

[createo]

Yes Yes.
I use google translate regularly, but certain nuances of technical language sometimes give rise to risky translations ... and as I am very visual (with diagrams and situations), a lot of technical writing is not always obvious ...
But I use it quad even a lot

thanks

[robcat2075]

I appreciate your persistence!

[robcat2075]

 

Examples and Context.

the red ones are the most important.

Kinematic - makes the end of a chain of bones seek a target (without having to pose all the bones in the chain). Legs are the most common use

Aim at - knee and elbow pointers are the most common use. You could control two eyeballs at once by making them aim at a common target null or bone.

See "Simplest IK Leg" and "Adding an IK Leg" on my Tutorials page for examples of Kinematic and Aim At use.

Orient Like - The most common use is for "fan" bones. You can see an example of a fan bone in" CP Weighting vs. Fan-Boning"

Translate to - A bone that is a child of another bone will inherit both Translation and Rotation from its parent. A Translate To constraint is a way of making a bone get only translation from another bone. A head that is on the top of a spine could follow the spine without having to rotate like it.

Roll Like - useful for creating partial rotation. When your hand turns (as if it were turning a door knob), the skin by your wrist turns the most, the skin by your elbow not much and the skin in the middle about half way in between. Putting the CPs for the middle skin on a bone that is constrained to Roll Like the hand, but only 50%, will simulate that... without following any of the hand rotation on other axes.

Aim Roll (Handle) At - permits a target to influence only the Z-axis roll of a Bone. "Gas Pump Hose" on my Tutorials page uses Aim Roll At to keep all the bones in a chain aligned.

Path - Often seen in tutorials where you animate a walk "cycle" and make a waling character follow a path.  A more practical use is to make chains of bones conform to curvy paths. See BasicWormCrawl in https://forums.hash.com/topic/45166-path-constraint-for-a-bone-chain/?tab=comments#comment-387426

Surface Constraint creation example.

Euler, Spherical and Translate Limits are rarely used in characters.

Group is like a Translate To Constraint to make a bone follow a Group of CPs rather than a bone. I use this to attach buttons to groups in simulated cloth see Chicago Bears fan in simcloth Hawaiian shirt with buttons and collar

 

 

 

[createo]

Hello,

Thank you very, very much for your help !!
I test all this
Good day

[Fuchur]

I would recommend "https://www.deepl.com" instead of Google Translate.
It is much (much...) better than Google Translate.

Best regards
*Fuchur*

[createo]

Thank you Fuchur, very good recommendation !!

[robcat2075]

I will add that most Constraints can have "offsets". Offsets will be made automatically when "Compensate Mode" is on. Compensate Mode is turned on by default when you begin to make most constraints.

So, with Compensate Mode ON, if you Translate constrain Bone A to Bone B while it is 5cm away from Bone B, Bone A will follow Bone B... and always maintain that original distance relative to Bone B.

An example use is when a character has to pick up some object.  The model bone of a hammer doesn't need to be Translated exactly to some bone inside the character's hand, causing a pass-through. The hammer can be moved so it looks like it is touching the hand, then the Translate and (Orient Like) constraint is made, and the hammer will maintain the appropriate distance (and rotation) relative to the hand.

Similarly, bones do not need to be physically attached to another bone to be a child of it. They only need to be a child of the bone in the PWS hierarchy and they will follow from any distance.

Note that while constraints can be turned ON and OFF during an animation, parent/child relationships can not.