Rigging

Quasar · Feb 2005

I was messing around today in max 6 and built this ammo feed chute; anyone know how I can rig it? The tabs sticking out the ends are spring steel that flex and make the chute springy, the sections connect with each other via four hooks.

The chute has to be able to bend up, down, side to side and twist along its length. I bet it's a lot of work.

Thanks in advance!

Thermidor · Feb 2005

I dont know about max , but in maya i would use a spline ik for the main body parts , and indevidual IK chains for each bit of flexablke metal , if you wanted them to move ...

hawken · Feb 2005

I've been looking into how to make a bones setup for a tenticle and this is pretty similar, you need to do the bones as normal and then set up ik modifiers.

hawken · Mar 2005

just been sifting through my max6 book and theres a tutorial about how to do ik splines, which should be applicable for this. Click help in max and type in IK spline (as the book is also a help file in max6)

Quasar · Mar 2005

I've been reading through that, thanks. I'll have something working sooner or later

Badge · Mar 2005

SDKs could work as well right? that way you woulnt have to paint weights eh?

KMan · Mar 2005

I'd just link up all of the separate pieces to wach other going up with their pivot points set wherever you need to. You can then use the IK Spline solver or whatever it's called (only used it once, for a class assignment) and work it like that. The user reference should have better info in it than I can provide at this time of night.

Z_z

Quasar · Mar 2005

I tried out the spline IK solver for controlling the whole chute and it works well, but I have a tiny problem. I have to create a spline IK chain for each connector piece so that they flex with the chute, problem is that I can't seem to clone it. Is there a way to do it without messing things up? Creating each IK chain manually would be a pain in the arse considering that there are six for every element and maybe 30-40 elements in the chute (depends how I use it).

Here's a pic of the IK chain I made for controlling a connector piece; the mesh it controlls in skinned and properly weighted, I just have to make a lot of them.

Cubik · Mar 2005

Not sure if this is what you're asking about, but this is what it says in the helpfile:
"There are two simple rules to follow when mirroring a character rig with bones and IK. The first is that the IK chain's Parent Space has to be set to Start Joint, not IK Goal.
The second requirement is that the root of the IK chain must be linked to something that doesn't have IK on it. You can tell whether this is true by looking at the Motion panel. "

Quasar · Mar 2005

I've been trying to think of how I can accomplish this, but I don't know if it's possible with the IK system; it's hard to explain what I want, but here goes!

This is something I made using the array tool (it's not an IK chain)

In this pic it's easy to see that each element is actually made from two halves that rotate along their width when the chute twists. I'm wondering how I can simulate this with an IK setup so that I don't have to manually do it with each element.

CrazyButcher · Mar 2005

cool illustration, the link looks quite complex in tech for just "flying away" like the shells, after used, wondering if that's a real design or invented for the looks ?

if slight errors would be toleratable, I'd probably try a combination of path-deform for links, and the ammo controlled by the same spline (no path deform as deformation would look more obvious on the round projectiles)
this would be my first approach, not sure if it would work and be as controllable as you need it.
probably some sort of script, where the chain is represnted by 2 splines parallel could work too.

oh and happy easter

Quasar · Mar 2005

Happy Easter to you as well Butcher, and everyone here at Polycount!

The chute elements don't fly away, they stay in one place and channel the ammo into the receiver of the weapon from the ammo source. I placed ammo into the chute to convey what it looks like when in use, I guess it created some confusion. The ammunition chute is actually very important because if the ammo isn't guided into the weapon, properly aligned, there would be trouble; just think what would happen if the bullets got caught on something while being pulled into a gatling gun that fires 100 rounds per second...Usually any cannon with a caliber of 20mm or higher uses a feed chute regardless of its firing rate though for, smooth operation.

Here are the two chutes that I based mine on:

25mm

30mm

(got the 25mm pic off of Navy News, and the 30mm one from another .mil site, forgot which one)

I think you're right about creating a script, too bad I've never done that before, I'll have to look through the reference.

CrazyButcher · Mar 2005

I missed something that connects the projectiles, ie is used to "pull them in" hence thought about it the wrong way,but thx for the shots, I think the minigun uses similar system, eventhough less caliber. when I was in army we just had the cheap links, though the weapons werent as "big" as this stuff

depending on what max version you are on
http://www.scriptspot.com/Main_Scripts.asp?BrowseType=Controllers&Sort=Name

you might find something more to play with

my idea would be, using one spline as the "back" and create align points, by looking at the opposite spline (same percentage, lets say at half lenght) then you have a lookat vector in that direction, the other up vector would be along the spline to the next node, crossproduct of both would inhibit "rolling" of the links. since back and front spline have different "up" vectors you could use that to define the bending of back/front.
I am not on max7 so I cant check the lookat-upnode-controller scripts that are presented there, but actually those + a script that auto generates those nodes along the splines would by my approach

Quasar · Mar 2005

I have max 6 so I can't try them either.

I'm thinking of wiring the twist angle of the chute directly to the rotation angle of the element halves since they're directly related. There are so many variables to think of; I'm confused...

CrazyButcher · Mar 2005

actually out of the box max should work somehow
here is a basic setup, I just threw together

better would be putting the pivots in the middle of the shells

http://crazybutcher.cube3d.de/wip/belt-fed.zip

you create 1 spline, and copy it to create a second parallel to it,
create a shell and link it via path constraint to spline1 ( remove the animation of it to make it static)
create a dummy object parallel to it on spline2. link the dummy with path constraint to spline2. after that link the shell with a look-at constraint to the dummy, and setup axis so that it will point to the dummy.
then instance clone the shells+sphere along "up" direction and see that you will get a chain.
now the only thing you need to do is animate those splines.
probably need to fiddle with them a bit to keep a constant distribution (use smooth instead of bezier)

to make the links rotate at half.. probably a bit more tricky, I would experiment with 1 dummy along spline1 which "banks" along the path, and the dummy along spline2 banks too. then set up an addition orientation-constraint for the links, one time using spline1dummy and one time spline2dummy

Quasar · Mar 2005

That's a neat idea, I forgot about the look at constraint, d'oh!

I don't like the idea of manually controlling the shape of the splines, so I'm thinking of having two spline IKs, each with about six control points, then creating a chain of six bones between the two splines and linking the bones to the spline IKs' control points. In other words, when I move the bones in the middle, the two splines will conform to them and always have an equal distance between each other. After creating a rig like that, I can mess around with the look at constraint, and if that fails, I can write a script with a bunch of "if" statements heh. I can also make the chain of bones in the middle a spline IK, and the ammunition can fallow that path.

pyromania · Mar 2005

I did this in maya, but the same things should apply in MAX. You create a joint for each link of the chute, then parent each link to its joint. Then to keep things from intersecting you figure out what the max and min rotations you want to allow for a joint and limit the joints. Now to move everything, create a indentical set of joints, and put a IK spline on them. Then you setup a relationship so that the rotation values of the spline joints drive the rotation of the chute joints. Since the chute joints have limits, the input from the spline IK will never make the joints collide.

Delaney King · Mar 2005

Dont forget space warps too. There may be something there to help you.

Also dont forget you can skin directly to a spline if your spline Ik isnt so crash hot.

Quasar · May 2005

Ok, I think I almost have a working system here.

I used Reactor instead of IK, it seems more logical as it gives me greater freedom. I'll be rigging the metal connecting tabs so that they flow with the chute and don't clip through it, I'll also link some spline IKs to the rigid bodies that control the chute, which will guide the ammo. And thanks for the comments

Quasar · May 2005

Ok, I'm stuck again...

I'm working on getting the ammunition to flow through the chute properly aligned, but I can't get the bullets to face the right direction after trying Crazy Butcher's idea. Basically what I have so far is a spline with all it's control points linked to the rigid bodies which gives it the same shape as the chute. I'm thinking of maybe attaching the bullets to a spline IK chain running along the previously mentioned spline which would keep the distance between the ammo, but I'm pretty much stuck there because I have no clue how to get them rotated properly...

CrazyButcher · May 2005

hm my 2 spline idea should work no ?
you have one spline for the actual position dummy of the ammo (end)
and the other one as lookat target (front), would give you aligned bullets, when both use same spacing along their splines.

to animate them you would need to animate both dummys along the spline

Quasar · May 2005

Your idea works ok, but the bullets are off by a few degrees. Somehow the bullets and the dummy objects have to pass through the spline control points at the same time in order for this to work properly. I also tried placing a bullet on a spline in the middle of the chute and create two other splines on the left and right then constrain two dummy objects to them. I then gave the bullet two look at constraint facing both dummy objects, as this might average out the timing making it properly aligned, but the bullet just freaked out and it wasn't working...I'm running 3dsmax 7 now by the way.

Quasar · May 2005

I have a working system now

(700KB, requires DivX codec)

I basically got the ammo aligned properly by using your idea Butcher, only I added to it. Basically each bullet has it's own three short splines, one for a dummy object on the side, another for the bullet and a box, and then I have an extra third one above the bullet spline that also has a dummy object. The bullet looks at the dummy object on the side and the box looks at the dummy above it, the bullet then uses the box as the upnode. All this is then cloned and put together in a chain with a single slider controlling all the bullets. After each bullet reaches the end of its spline, it snaps back to the start and creates the illusion that the bullet behind it is now moving along its spline. I hope that all makes sense

I should also mention that I was too lazy to make links attaching the bullets, ah well.

CrazyButcher · May 2005

cool

now where is the multi-billion poly gun

one side note, atm it looks too much like a conveyor, while I havent seen similar belt-feds in action, the ones I saw in army the belt was abruptly pulled in after each shot. so it's more of a quick pull, wait, quick pull, wait.. kind of movement.

Quasar · May 2005

I'll incorporate this chute into some project later on, it's more of a "Just to see if I can do it" thing. When I do use a feed chute, I'll make a better one using this as a template.

As for the flow of the ammunition, I was just trying to demonstrate that I got it to move through the chute

That is how ammunition flows into gatling guns though, it's a smooth continuous motion as the ammo is reeled into the rotor assembly. If it's a chain gun, or a recoil/gas operated weapon then yeah, the bullets would be pulled in abruptly one at a time as the bolt assembly slides back.

killingpeople · May 2005

*tear

it's so beautiful. *sniff

Rigging

Replies