Where is DOP position coming from?

[catchyid]

Hi,

In DOP import node (inside a SOP), there is a check-box "Transform Geometry with Position Data". HOWEVER, in the simple scene attached, when I inspect the Geometry Spreadsheet for the DOP network (e.g. boxes RBD Packed object), I don't see any "Position" Data, I just see "Geometry" Data! Is this normal? Obviously, the DOP Import is reading the geometry Data OR am I missing something ?

Thanks,

testing_forces.hiplc

[galagast]

I suppose this is normal for the RBD Packed Object DOP...

In comparison, if you drop an RBD Object DOP then inspect it on the spreadsheet, it has a Position Data by default. Internally, that data is being set by an RBD State DOP.

On the help card, it says:

Quote

RBD State’s are automatically added by the RBD Object DOP. This DOP is usually used to override the RBD Object’s parameters.

I guess the Position Data is there so that we could have additional control/adjustments to the object being simmed. These modifications SHOULD then travel out of DOPs land all the way back to SOPs via the DOP Import.

Just my two cents

H15.5.607 Indie

rbd_object_position_data.hiplc

[catchyid]

Thanks Jeff and sorry for this late reply So, it seems that internally, if there is no position data, geometry is read instead.

You said: "I guess the Position Data is there so that we could have additional control/adjustments to the object being simmed", If I understand you correctly, do you mean that one could add Position Data in RBD Packed Object and somehow control it from the sim (maybe using VEX that writes to it directly, or using a script to write to it...)? 

 

[galagast]

Quote

Thanks Jeff and sorry for this late reply

No worries Khaled

Quote

If I understand you correctly, do you mean that one could add Position Data in RBD Packed Object and somehow control it from the sim (maybe using VEX that writes to it directly, or using a script to write to it...)? 

In the case of RBD Packed Primitives, Position Data is not necessary. From what I understand, it is because RBD Packed primitives are handled differently in DOPs.

Historically for fractured objects, it used to look like this in the spreadsheet: (pre-packed primitive days)

Each of those piece* Objects has its own individual Position Data.

> To modify say.. the position, you use the Initial State tab.
>> The Initial State tab is internally the RBD State DOP.
>>> The RBD State DOP is the node that creates the Position Data.
>>>> Lastly, this Position Data is the one that is read by the DOP Import SOP > Transform Geometry With Position Data parameter.
 

When packed primitives was introduced in H13, the spreadsheet now looks like this:

It now only contains a single piece of Object for all the fractures.

> As with above, if you want to modify positions, you also use the Initial State tab.
>> The Initial State tab is internally a Transform SOP.
>>> The Transform SOP modifies the Geometry directly, thus it does not need to create Position Data.

If you would like to further modify the position (and other attributes) in DOPs, I believe you are correct, it will allow you to use VOPs/VEX/SOP Solver etc.. As long as you are modifying the Geometry Data. I just don't know the extents or limits to doing so.