Soft Body (sbd) Spring Constraint

[MENOZ]

hello!

i want make a sheet that fall down following a path.

i'm doing this using a cloth solver on my grid (the sheet) with a Spring Constraint.

i make rough animation at obj level of my undeformed grid, and in DOP it solves. it seems ok, but here's the problem:

i want my sheet stops where i want, and when i want. If my animation at obj level stops at frame 100 now i have my cloth that coninues to jiggle around for long time. i want it go there and stops

how can i do?

thanks

[Rafal123]

hello!

i want make a sheet that fall down following a path.

i'm doing this using a cloth solver on my grid (the sheet) with a Spring Constraint.

i make rough animation at obj level of my undeformed grid, and in DOP it solves. it seems ok, but here's the problem:

i want my sheet stops where i want, and when i want. If my animation at obj level stops at frame 100 now i have my cloth that coninues to jiggle around for long time. i want it go there and stops

how can i do?

thanks

You mean something like that?

cloth_stop.hipnc

[MENOZ]

You mean something like that?

hemm... no

i want to control where my object fly before it stops, and i do that as i wrote above. my poroblem is to stop the object.

[MENOZ]

hemm... no

i want to control where my object fly before it stops, and i do that as i wrote above. my poroblem is to stop the object.

maybe i found that the problem was the density too high of my cloth object. but it's strange that pulling up the strenght in the spring constraint to something like 5000 it donesn't affect the simulation. why this? the density was about 4, instead of 0.1

anyway i made another test, here i have a problem on frame 43, the cloth object pops his position, here's the file.

thank you

cloth.hipnc

[Andrzej Majewski]

maybe i found that the problem was the density too high of my cloth object. but it's strange that pulling up the strenght in the spring constraint to something like 5000 it donesn't affect the simulation. why this? the density was about 4, instead of 0.1

anyway i made another test, here i have a problem on frame 43, the cloth object pops his position, here's the file.

thank you

If you change primitive type on the grid to "mesh" it will work fine, but there are very big forces, so maybe using some drag force will be necessary.

Edited March 7, 2008 by Andrzej Majewski

[MENOZ]

If you change primitive type on the grid to "mesh" it will work fine, but there are very big forces, so maybe using some drag force will be necessary.

yes! it works now! i added a drag force as you said, and it prevent the "explosion" of the cloth, but see, when my animated grid stop the cloth continue to oscillate for long time. how can i stop that?

[Andrzej Majewski]

yes! it works now! i added a drag force as you said, and it prevent the "explosion" of the cloth, but see, when my animated grid stop the cloth continue to oscillate for long time. how can i stop that?

You can keyframe drag force. Set keyframes for drag force (let say to "1" in frame: 120 and "100" in frame "200") and pick "use always" instead of "use default". It should works.

AM

[MENOZ]

You can keyframe drag force. Set keyframes for drag force (let say to "1" in frame: 120 and "100" in frame "200") and pick "use always" instead of "use default". It should works.

AM

i tried different values and timing, but the effect is not so controllable. it alwais jiggles.

i found in maya nucleous a parameter called Motion drag, it says:

A force is applied to each object being constrainted that pulls it more towards the motion of the other object. At a drag of one the objects will be fully locked and move together.

how can i configure my houdini scene to do the same?

thank you!

[Andrzej Majewski]

i tried different values and timing, but the effect is not so controllable. it alwais jiggles.

i found in maya nucleous a parameter called Motion drag, it says:

A force is applied to each object being constrainted that pulls it more towards the motion of the other object. At a drag of one the objects will be fully locked and move together.

how can i configure my houdini scene to do the same?

thank you!

I don't know maya at all, so I can't help you. But in this simulation you can use Switch Solver and switch from cloth simulation to RBD solver or Static Solver. In this case it doesn't matter.

But now I have question too. Correct me if I'm wrong: RBD AutoFreeze can work only with RBD simulation? Clothes (or wires) doesn't have angular and linear velocity, so AutoFreeze will not work... Am I right? Is there any other way to freeze simulation for clothes and wires?

AM

cloth.hipnc

Edited March 7, 2008 by Andrzej Majewski

[MENOZ]

so, switching to rbd i can't use the motion of a cloth object to continue to evaluate the rest of the movement in rbd simulation... right?

i'm a little confused.