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View Full Version : I few questions im stuck with..

03-17-2003, 10:50 AM

Ive got a few questions/problems im stuck with in max 4. Firstly can you have a position constraint on one axis. And another on another axis?

Does anyone know how write a max expression to say: A is evenly positioned between B and C in the say x axis?

Basically i want to constrain an object between 2 others but have different amounts for different axis so for its x it moves 50% z the same but for y 50% / 10?

Also does anyone know if its possible to do additive blending with poses comprised from CA?

Any help,


03-17-2003, 04:05 PM

03-17-2003, 05:20 PM
Hi Eek,

Jon Baker pointed this out to me. I'm just learning expressions so not too techy with them but I tried something which seems to work.

If you have two objects A and B and you wish to have object C mid point between A and B in only the X plane this seems to work

[(A.x+B.x)/2, 0, 0 ]

Where A is object A's world position and B is object B's world position.

Maybe this isn't what you mean, or maybe it falls on it's arse in a rig, I've just tried it with loose dummies?



03-17-2003, 05:25 PM
Hi jol,

No that sounds right!, Its for my Facer8/gollum rig, to give me some more jaw control. But conventional way dont work so i'll give it a try. Can i apply the same expression but to the other axis?

Thanks again,


03-17-2003, 05:41 PM
Hi Eek

I think if it works OK it should work in all axis. Use the (A.x+B.x)/2 in the X plane and (A.y+B.y)/2 in the Y plane and so on for Z.

If you want a value other than the mid point I guess (A.x=B.x)*0.75 would give you a three quartyers position for example.

Haven't checked to I could be very wrong, let me know if it works.



03-17-2003, 05:49 PM

Just tried this and it works ok with loose dummies. The object is at the mid point between A and B on the ground plane (x and y) and one quarter of the vertical distance (z) between A and B

03-17-2003, 06:13 PM
Im stuck,

Jol i can't seem to make it work, i made 3 dummies split there axis and then put an expression float on the middle points x axis, i did what you said in the expression window and nothing happens!! Please tell me how to do it.



03-17-2003, 06:18 PM
Its fine i figured it out! thanks.


03-17-2003, 06:25 PM
Ahh...it might be that I am doing something slightly different.

When I create the variable for the expression (the A and B) I check vector and then I assign it to the actual name of the dummy.

This means I choose the name of the object and do not expand the trak to get to the not to the Position controller of the dummy
(which I have left at a Bezier Position controller not an XYZ Position controller).

This seems to be an undocumented feature but if you assign to the name of the object (the top level I guess) you get it's world position coordinates. This means it doesn't 'lose' it's sense of position to the root of a hierachy it may be part of.

Using this it is possible to attach 'squashing' extra bones to Charater Studio 3 for example.

03-17-2003, 08:44 PM
Hi Eek,

I can't help you with your problem, that's why I got Jol on here;)

Is there any chance you could help me out with one though?

For the animation challenge I've got in mind a character who can extend his tongue (like toad in XMen).

I'd like to make a variation on one of your spline rigs that you posted. The one that has the bone following the spline. I also need it to squash and stretch and to be able to have both IK anf FK if possible.

Any suggestions on doing this in max?


Jon (Baker)

PS Hope all goes well with the new facial rig additions.

03-18-2003, 09:45 AM
Hi jol,

Is it possible to run this expression with rotation? do i have to split up the axis ,or use scalar expressions.

Blowtorch hi,

Ive just finshed yesterday StretchySpine v1.0, it doesnt use bones though and at present isnt fk you just control it with 3 controls.I'll post it today as alot of people are intrested in it.
I may possibly add fk controls today.


03-18-2003, 09:55 AM
Hi Eek

I'm not sure. If you have a vector (V) or three value expression like x,yand z rotation the using the V.x V.y or V.z expression gives you access to the x y or z components of the vector.

I guess this means a rotational expression could use it though I havent tried. If I get the time this afternoon I'll have a look.



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