sloooooow simulations

[Broomy]

hi all,

i am having troubles making a realistic car rig that is simulated not keyframed. I have the actual rig sorted it is the simulation that is the problem. Not only for this but many others that i have attempted, the simulation is very slow. I have incresed the mass hugely and reduced any dampaning/friction etc.... to 0. So im still not sure why it is so slow?

Is there a "simulation rate scale" for ridgid bodys such as in fluids?

Just as a note, i have the rig and helper (low res objects) at real world scales Ie the box/car is 4 meters long.

any help would be appreciated

[sunder]

What are your machine specs? Also how dense are your rigid bodies?

[Broomy]

hi sunder

cheers for showing interest :)

My machine specs are

2.4Gig P4
768Mb Ram
Ati Radeon 9800 Gpu

WHen i am saying slow simulations i dont mean they are taking along time, what i mean is that if i bake out the simulation and render it to 25 fps it will be moving really slow as if it was a slow motion camera (if that makes any sense, lol)

As for density of the object i have no idea what u mean? :confused: Could u exiplain it a bit please

Thanks

[sunder]

Ah I see :p
You should try changing the field magnitudes. If your car is 4 meters long and it takes up 400 default grid spaces in Maya, you're probably working in cms. So set your gravity magnitude from 9.8 to 980.
If that doesn't work, you can just use the bake simulation and speed it up by shrinking the keys.

(By density, I meant how many polygons/points do your rigid body objects have. But you're already using lo-res proxy objects, so they should be pretty low already)

P.S If you need a more detailed explanation, let me know

[Broomy]

hi

cheers saunder that makes alot of sense.... 9.81m/s sqaured, not 9.81 cm/s sqared right!!! :rolleyes:

cheers again

[Broomy]

hi again

just another question (didnt see the poitn of starting a new thread :D )

When applyinng a hing constraint or spring constraint, doesnt matter really, i was reading in the docs that u can select 2 ridgid bodies and apply the constraint ot them both. Now this i can get to work most of the time but sometime it just completely breaks the sim that im doing, is there any particular order that u should select te object in (I.e parent first/last)????

Cheers


edit - or any other tips tricks that might help with this? :)

thanks

[sunder]

Hi Broomy :)
What and when exactly does it break?

[Broomy]

hi

lets see if this will work?!?!?!


hmmm?


double hmmm???

i can seem to get any pics working???

Well, it is said thata picture paints a thousand words so this shouldnt take long ;p!!

I have made a rig that does not include wheels, kinds useless ona car rig!!!! But does have suspension, wuuu!!! yay!!! I have done a playblast of this rig falling using Gravity (at the correct scale , cheers saunder) and it bounces as a car should,

it consists of:-
..................................P.....................P.........................................
....................BOXB----------BOXA-----------BOXB............................
.......................|................/.......\...............|.................................
.....................S|.............../..........\.............|S...............................
.......................|.............H.............H..........|..................................
....................BOXC------/.................\----- BOXC............................

Ah ha a picture!!!!

P = Pin Constraint
H = Hinge Constraint
S = Spring Constraint

So hopefully u should be able to see what happens???

My question is that when i create a Nurbs (For smootheness) cylinder to represent the wheel. I make it an active ridgid body and apply gravity to it in the Dynamics relationship editor window, then put a hinge constraint between the Cylinder and Box C.

This should then bejave correctly and like a car should, insted it completely destroys any of the bouncness in the spring constraints and just drops to the floor ridged and dead.

If u can have any idea what im talking about ill be impressed

Cheers

[sunder]

I tried to recreate what you have in the figure and after applying the hinge constraint between the cylinder and boxC, the springiness indeed stops. I think this might be because there are one too many hinge constraints affecting the C boxes, thus restricting their motions. Try a spring constraint instead.
Nice ASCII art btw ;)

[Broomy]

I be Ascii!!!! you wount believe me if i told u how long that took!!! :redface:

anywho, u now fully understand my problem, is there an order of what u should select first or last?

And when u say a spring, is that instead of the hinge between BOXA and C or between BoxC and the cylinder, not sure abouth the results of that??

I shall try later but for now back to work and modelling stuff :hello:


need some :coffee:

laters