Whew, it really gets me confusing in Dops.
I would group objects with some attributes and give different forces to it whenever I want in Sops but not in Dops, I can't find a work around.

Here goes some question about Dops!


1 I want the RBD objects get affected only by fan force for maybe 5 frames or until it gets
certain verlocity that I want first
and once it pasts a certain frames or it gets a certain velocity that I set, I want the object to pick up the second force How would I acheive this?

(I was thinking of group dop but it's quite different from group sop..)

2 Grouping object by attribute, how would I do that? I was looking in help doc but no example was there. Does it have to be always Affector?
How would I use Mask string to filter object by attribute in Geometry such as velocity or position.


Attached file has secondary force which I want to happen after the first force such as fan for say 5 frames later.

Hello,

1) An expression such as $FF >= 50 in Activition parameter of the Force DOP would make it active at frame 50 or higher.

2) You could group by expression using Group SOP, say $VZ > 5.0 and points that evalute true would be placed in the group, maybe that's not what you want and i'm sure there's a much better approach than mine.

Hope these helps!

eitht.

Thanks for the approach but I need to group the objects in DOP by it's Y position value or such Velocity.

Something like $TY > 10 or $VX > 10 expression to group points in Sop group node. but in DOPS.

so I can activate my force with that and mix 2 force more smoothly by multiplying the force corresponds to it's position or velocity.

Keyframing activation is making the 2 force just switching somehow. I even animated the strength but still quite look like switch.

I just want to create attribute for points in DOPS as SOPS so I can apply force when or however I want.

you should have a look at some basic dop tutorials in order to get an idea how DOPs work, looking at your questions you could really benefit from it
Have a look at Gnomon's Rigid Body Dynamics DVD for example, a lot of your questions will be answered in there.

If you want to apply a force based on an objects attribute you can do that even in the force's activation parameter itself by doing a dopoption() expression.

Something like this for example

if ( dopoption( $DOPNET, $OBJID, “Position”, “vely”) > 10, 1, 0 )

if you want to create your own attributes in DOPs, you can create an “empty data” DOP, apply a modify data DOP in order to create a new subData set for your object and connect that via an “apply data” DOP to a dop object. Once you've done that, you can then access this new data with again a dopoption() expression or with dopfield().

Cheers,

Manu

Thanks for the quick reply.

It seems like Gnomon does not have the DVD anymore?

If I activate the force with the expression, it would do that but is there a way to look at point position/velocity and multiply the force to the point position/velocity value in DOPS?