Dynamic Constraint

[John Bigboote]

I just love that DYNAMIC CONSTRAINT! I use it all the time, EVERYWHERE.

 

Want to make your character look drunk for hoots? After animation is done... put a DC on it's head control-bone, switch it to 'Spring' -turn gravity OFF and set a angle limit (around 30 to 40 deg) hit PLAY and be ready to GIGGLE!

 

My question is about the 'Collision Detection' feature on the dynamic constraint... what does it look for- geometry/mesh or other bones? Is anyone able to say 'Yeah- I use it all the time- it works great! Here's the trick!"

 

Just wondering!

[HomeSlice]

In some versions of AM (v13?) there was indeed a trick to calculating object collisions. I think it was fixed at some point but I'm not sure now. Everything I know about it is in the "Object Collisions" chapter of the Dynamic Constraints tutorial. (yes, this is a shameless plug)

http://www.hash.com/forums/index.php?showtopic=29914

[Gerry]

I've downloaded the tute and it's terrific.

 

EDIT: I had some questions but I'll finish reading it before I ask any.

[John Bigboote]

Yup, Thanks Holmes!

 

Here is a quote from your tutorial that I did not know...seems just crazy enough to work! How did you EVER figger this out---and is it still of 'pertinence'... me wonders.

 

QUOTE:

Important! In some versions of the program, simulating object collisions only works when you are looking at the

|Choreography| window from Front view ( [2] on the numeric keypad ). The simulation will fail if you are looking

from any other view, including Camera view.

[HomeSlice]

Yup, Thanks Holmes!

 

Here is a quote from your tutorial that I did not know...seems just crazy enough to work! How did you EVER figger this out---and is it still of 'pertinence'... me wonders.

 

QUOTE:

Important! In some versions of the program, simulating object collisions only works when you are looking at the

|Choreography| window from Front view ( [2] on the numeric keypad ). The simulation will fail if you are looking

from any other view, including Camera view.

 

I didn't figure out that one myself. Stefan Gross said in one of his posts that the "front view" trick was necessary - forgot which AM version it was necessary in though. I haven't tried Dynamic Constraint Collision Detection since I wrote that tutorial.

[Gerry]

Okay, at the risk of sounding stupid, I've tried going through the tute three or four times from scratch and cannot get the "Control the middle of the Dynamic Chain" to work. After turning off the original constraint on the end of the rope, I followed the steps carefully and the whole rope stays rigid.

 

I then closed without saving, and placed the Dynamic Constraint on a bone in the middle, followed all instructions, and the whole rope points rigidly at the null. The rope bends at an angle at frame 1 but then goes rigid in successive frames.

 

Any suggestions on what I may have missed are welcome. I'd post the .prj but it's identical to the tute .prj. Here's a screen shot of my settings.

 

EDIT: the first half, controlling the end of the chain, seemed to work fine.

[Gerry]

I'm using some DC's in my holiday animation but it appears the bounciness is different from a wireframe render to a final quality render. In fact in final quality there's little to no bounce at all. I've got "Is Rod" set to ON and a stiffness of about 30%. At 20% in wireframe it's limp as a dishrag and at 30 it's about right, then in final quality it's completely rigid. Anyone have an idea about why this happens?

[HomeSlice]

Hi Gerry,

I didn't see your Sept 11 post until today. I'll go through the tut in the next few days and try to figure out why your results do not match the tutorial.

 

You will probably get more consistent results if you "simulate spring systems" after you are finished animating. After you simulate the spring systems (which include dynamic constraints), turn off the dynamic constraint (set it's enforcement to 0).

[Gerry]

Hey Homes, anything you can tell me about that question from 9/11 will be appreciated, but my question from today is something I'd like to figure out asap. It's not a fatal problem, but if you've seen my christmas animation in the WIP forum, I've rigged the big red bow to bounce around with movement. In wireframe it's great, but when I render to final quality it's completely rigid. Maybe I should post some quick renders.

[NancyGormezano]

I've rigged the big red bow to bounce around with movement. In wireframe it's great, but when I render to final quality it's completely rigid. Maybe I should post some quick renders.

 

Dynamic constraint (render on fly) seems to behave differently if you final render with multi-pass (each pass behaves differently) - however my guess is that if you do what Holmes said - simulate, and then turn off enforcement of constraint - it should probably work (I have not tried)

[Gerry]

I went and rendered some tests before I digested Homes' reply, and the DC's work fine in the tests, so I was completely confused! I won't even post them here, rather I'll go back and try his suggestions.

 

EDIT: Hey I'm watching the render and it looks like it's working great.

[HomeSlice]

Gerry I just went through the Dynamic Constraint tutorial and I didn't have any problems/

After turning off the original constraint on the end of the rope

You don't turn off the original constraint. You just set the original dynamic constraint's Target to the default value (none).

Then you make a new dynamic constraint on a bone in the middle of the chain.

So you have two dynamic constraints on the chain: one at the end of the chain with no target, and one in the middle of the chain with "null1" as the target.

 

Also, you won't notice any effect on frame 0. Go a least to frame 1 and then drag the null around and se what happens.

 

Does that help any?

[Gerry]

Thanks, I'll try that soon. BTW Your tip on turning on "simulate spring systems" and turning off the enforcement is working great on my christmas project! Tnanks!