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Weevil
07-28-2005, 07:07 AM
I am trying to get a cloth to drape over a box on a table but the cloth just falls right through :thumbsdow I tried the effect on a simple ball and plane and it still doesn't work.

The documentation seems to dodge that basic question: How do I get this to work? :mad:

I have noticed other people who ask the same question get no reply. Is this an ongoing issue.? :confused:

operation
07-28-2005, 08:05 AM
Hin

you need to put 2 materials:

ex: assign a surface to your sphere ( hard_sphere)
and assign a new surface to your plane (soft plane)..

inside cloth .. you must select a colision object ( choose your colision object by choosing the name of the surface ... ).

I know it's very bad documented, I found this by clicking and testing .. there is some tutorial on the net ( there is one on the NT website - search for : hard body collision with motion designer ... or something similar .. it's an HTML tutrial )

Hope it helps ..

Cheers !

Operation
Mourad K.

Dodgy
07-28-2005, 09:46 AM
Did you apply Collision to your box?
Did you select 'Object' as the collision type?

Did you go to the collision tab in the Cloth panel and select 'All' in the Collision detect field?

Surrealist.
07-28-2005, 02:22 PM
EDIT:just read dodgy's response again - oops. OK but here it is anyway.

The set up is simple yet badly documented. This is the same for hard FX as well as any type of dynamics that include collision.

In any dynamics set up like this you must always have 2 components. 1) the object that collides and the 2) collision object.

Each must have dynamics applied. The collision object is the box that the cloth drapes over. You must assign dynamics "collision" to the collision object.

Then the settings such as bounce power and so on will begin to take effect and the rest of the documentation - or most of it anyway will begin to make sense.

ece3k
07-28-2005, 03:20 PM
If you search the video tutorials on the newtek site, there is a pretty good example. I found it helpful. The trick is in the dynamics tab under object properties. In your case, go to your object that will be cloth and assign it a CLOTH FX dynamic. and the object its going to collide into a COLLISION dynamic. Adjust preferences to taste and hit CALCULATE.
The video tutorial shows some ways to speed up processing too...very nice. I prefer the metalink deform feature and the lowpoly substitute as a collision object.
For a table cloth, you are going to want to go into modeller and select some points that will be unaffected by cloth to hold the cloth to the table.
Good luck.
Erik

Weevil
07-29-2005, 06:49 AM
Thanks everyone but this is still not working. In L-8 inside cloth the only choices for collison are the plane itself and "all". Shouldn't the sphere be another choice or am I reading this wrong. :help:

When I run calculate with gravity the plane deforms to an invisible sphere and it sags right through the actual sphere. If I remove gravity and just animate the sphere (Hard is applied) it moves right through the plane.

Now here is the weird part. If I apply cloth to both objects they interact like some kind of chemical reaction similar to an alka seltzer in water. Cool, but that is not what I am looking for. I am going to continue to experiment.

I am lookin for the cloth video but cannot find it. It must have a different title. Does anyone know which video contains the cloth demo?

ece3k
07-29-2005, 07:16 AM
There is a setting in the cloth FX dynamic under the collision tab...set it to object.
Erik

Dodgy
07-29-2005, 09:02 AM
You haven't applied the Collision dynamic type to the table/sphere have you?

If you want cloth object A to collide with object B, you need to apply 'Collision' to object B, and cloth to object A. Then you need to make sure Collision is set to 'All' on the cloth object, and Collison type set to 'Object' in Object B's collison settings.

WizCraker
07-29-2005, 10:19 PM
I have this problem all the time with working with cloth. I can never get cloth to work correctly with the collision. The cloth always goes through the collision object for me. I can get a small center portion of the cloth to stay where it is suppose to but it just does not work. Causes more head ache in my opinion.

NigelH
07-29-2005, 10:36 PM
In my experience, accurate collisions come down to 2 things - resolution and time. Increaing the polygon count of both the cloth object and the collision object, and increasing the resolution of the calculation (under the 'Etc.' tab - lower numbers take longer). You get as much accuracy as you're willing to wait for.

On a related note, does anyone know of a way to 'smooth' or 'blend' the transition between the 'fixed' polygons and the 'cloth' polygons on a cloth object? I seem to recall that Motion Designer had such an option, but it seems to have been dropped from the new cloth dynamics engine. Anyone have any idea?

WizCraker
07-29-2005, 11:04 PM
Here is what I always get. Frustrating.

http://www.imagereality.com/Images/3D/Example/Cloth/Cloth001.jpg

serge
07-30-2005, 04:05 AM
Here is what I always get. Frustrating.
Hmm.. Few things that I can think of (however I don't know your exact setup/settings):
1. Try increasing Collision Offset.
2. Try lowering the resolution.
3. The weight of your cloth might be very high. In that case lower the weight, or increase Collision Offset.
4. Have you set the collision object (table) to Object, or Object-Subdiv? If not, try that.

Surrealist.
07-30-2005, 05:31 AM
In my experience, accurate collisions come down to 2 things - resolution and time. Increaing the polygon count of both the cloth object and the collision object, and increasing the resolution of the calculation (under the 'Etc.' tab - lower numbers take longer). You get as much accuracy as you're willing to wait for.

On a related note, does anyone know of a way to 'smooth' or 'blend' the transition between the 'fixed' polygons and the 'cloth' polygons on a cloth object? I seem to recall that Motion Designer had such an option, but it seems to have been dropped from the new cloth dynamics engine. Anyone have any idea?


You can set it to weightmap and have a fall off that way. Numeric Weight tool is good. You can set a linear falloff.

Darth Mole
07-30-2005, 06:18 AM
For starters, I'd make a much, much lower polygon proxy version of the table and use that for your simulation, and just replace the table mesh at rendertime.

I also cheat when cloth goes through objects, by running the sim and then scaling my object down slightly before rendering to avoid any polys showing through.

(And failing everything else, Cinema 4D's cloth is awesome...)

Weevil
07-30-2005, 07:49 AM
Thanks Guys! Especially Dodgy. The force is strong with you. That did the trick. Now that I got it to work I will play around with the settings to get just the right effect. Then I will post my project.

I wish I could answer some questions you have about L8 but I am not a Jedi yet. Thanks again! :thumbsup:

NigelH
07-30-2005, 11:51 AM
You can set it to weightmap and have a fall off that way. Numeric Weight tool is good. You can set a linear falloff.

Oh, right! I forgot about that. I actually went back and ran it through Motion Designer (good thing I still have 7.5 installed). The physics turned out better too for some reason (even with the same settings).

WizCraker
07-30-2005, 06:35 PM
Hmm.. Few things that I can think of (however I don't know your exact setup/settings):
1. Try increasing Collision Offset.
2. Try lowering the resolution.
3. The weight of your cloth might be very high. In that case lower the weight, or increase Collision Offset.
4. Have you set the collision object (table) to Object, or Object-Subdiv? If not, try that.

I'm using cotton thin as the preset, tried thick and get same result.