sure, see the example

You are welcome
I am glad you find it useful

I have made a little VOP SOP for you which will align first input geo to the second input geo by 2 primitives (one from each geo)

you just set two primitive numbers
and then you can correct the placement by angle parameter

it is very fast built, so it may be buggy

it will not work correctly if the two primitives you want to align have normals pointing in exactly the same direction(very small chance, but when you are testing it and place 2 exact spheres next to each other and try to align primitive 0 to primitive 0 it will happen)
It can be easily fixed by inserting the transform node before the first (or second) input and set the rotation to very small number just to introduce small difference in normals of the chosen primitives

first of all, your bomb RBD's collision volume is set to implicit sphere
display Collision Guide Geometry to see how it looks. As you can see this will create only one bounding sphere your whole particle system you are using as a collider. This means that the sphere will grow enormously fast and will push everything out

You can use magnet force with animated active parameter instead of object pushing geometry from inside

to retime the cached simulation use the timeshift SOP after the dop import in model object, delete default expression ($F) and use your own curve to timewarp the simulation, be sure to uncheck Integer Frames checkbox

here is a little example

assuming that they are both sops
connect both to Point SOP (each to one input)
now you can move the first one to touch the second in x axis by typing something like $TX + ($XMIN2-$XMAX) to the position x parameter of the point SOP
where $XMIN2 is the smalest x position of the geometry connected to second input and $XMAX is the largest x position of the geometry connected to the first input
at the end you need to use Merge SOP to merge Point SOP and the second geometry (which was used only as a template for the point sop so the output from the point sop is only translated 1st geo)
feel free to use $XMIN, $YMIN, $ZMIN, $XMAX … as well as $XMIN2, $YMIN2 … in your expressions to acheive desired effect
alse take a look at other useful variables like $BBX, $SIZEX, $CEX …

this will work for your example but it may be not usable for what you really want. Maybe if you can tell us what your real goal is (you mention more than 2 objects, maybe not in one axis?) then you can get more help from us

For me it depends on the modeling task i have to do.
If there is a need for parametric control over the model then i definitely choose Houdini but for orgaic modeling like characters and many other props
I still prefer modeling/UVmapping in other packages where i can model so much faster, i do not need the modeling history for that type of tasks. It allways ends up as obj file on disk anyways. Houdini is very good with external geometry, you do not need to include it in the scene and thus keep the scene very light.

It is up to your personal preference.
So if you are comfortable with blender modeling toolset there is no problem modeling in blender and do the rest in houdini. Meanwhile you can learn houdini modeling toolset . If you want to use Houdini in production you cannot avoid learning sops, so you can see on your own if the houdini modeling workflow suits you and for which type of tasks.

you should set pivot in uvxform1 to .5 .5 to scale to center

there is seckanluk_01.obj file missing in your scene so i can not test it

but from what i see in your RBD fractured object you heve Glue Strength set to -1 which means that it will not break no matter what
try setting it to some higher number

also you should have group for each shattered piece of geometry like piece0, piece1, piece2…pieceN and then specify group mask in RBD fractured object like piece*

thank you for your long answer msawtell

i am confused about cloth/RBD interaction, i thought that it is supposed to work together and it worked (more or less) in H9.5 so this have to be a bug then.

To the collision toggles, I was used to those type of choices (point/edge/face) in some other cloth systems and it is good to be able to turn off face and edge collisions if i do not need them to speed up simulation (I know that it will lower the accuracy for the reasons you described). But if it is not possible with houdini's cloth model then it is still ok with me. I have kind of used to accuracy-over-speed in houdini, however i am still hoping for both in the future.

the error message now makes more sense
but raises the question, why did my simulation stop?
i hope it will be resolved soon

Nevertheless I have to say that there is very notable improvement on H10 cloth, great work deveopers

thanks for reply jeff

I am glad that it should work

i am still not able to get mutual collisions however
not only with ode but with classic RBD too
I have started a new thread about this since it is not about ode anymore
http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=15653 [sidefx.com]

H10.0.260

I am not able to get rbd/cloth mutual collisions to work, only cloth is being deformed by RBD. I tried to lower RBD's density/mass to extremely low numbers but with no difference. Am I missing something obvious?
see attached file

I am getting error in cloth solver:
“Cannot retrieve data from previous solve”
it happens a lot
even in ParticleAndCloth Example file from help examples
EDIT: the attached file is only for the collisions issue, i am not getting this error in this particular file. But see above mentioned example file for this error

RFE: I have noticed that cloth collides with its faces (maybe edges/points too) this is very cool, but is it possible to give user control over which collisions will be used?
Like points/edges/face checkbox near the Cloth-External Collisions
and the same near the Cloth-Cloth Collisions
This is only if we can benefit in speed increase when face/edge collisions are turned off for initial tests for example.


thanks for any suggestions

you can do some small polybevel on the edges of the cube
it will correct your shading and keep your mesh closed so displacement will not tear it apart

I am not aware of that
but you have list of Local variables in help to each node which uses some hardcoded variables. For example Point SOP, Transform SOP, most POPs etc.

They are not necessarily linked to some existing attribute (like $BBX, $NPT. etc.).

However your custom attributes which are represented by variables can be seen by middle clicking on the node. There is Custom Variable Mappings section where you can see the corresponding pairs

YoBeardMaestro
…
However, it does still beg the question of: how would I access the point attributes Life and Life in expressions?
YBM

Here are the local variables you are after

$AGE (life)
$LIFESPAN (life)
$LIFE (life / life)

I am very happy with the addition of ODE engine into houdini
I have just one question about how it is integrated into houdini's “integrated dynamics environment” which I suppose means that everything should work with everything. But it seems that I am not able to get ODE and cloth having mutual collisions. Does it have something to do with the settings or it's simply not supported?
Is it possible to get impact data with ODE?

you can do this in channel editor
select bunch of keyframes
press y to enable scale handle
now you can scale to negative
you can also adjust pivot point for the scaling

1. in scatter1 SOP increase attribute bias to 1
2. in copy1 SOP go to the Attribute Tab and check Use Template Point Attributes to inherit color and alpha (and other attrs)

there is a seed for the whole POP
it's directly on the POP Network SOP, called Random Seed
this should give you what you want
but do not change it over time
just generate several simulations with different seed and save them to disk
then bring back with file SOPs and render together
there should be a way to render them directly from disk, but i have not done it in H9 yet

you can write simulation to disk using “ROP Output Driver SOP” or File SOP
as you tried, but also check the initialize simulation OPs in rop output driver sop

it may also depend on your POP sim start frame, so try to export from your start frame

also make sure that your Output file path contains $F variabile (the same for File sop to read them back)

i recommend you to delete all unnecesarry attributes (with Attribute SOP) before export to make the files smaller

check Initialize Simulation OPs checkbox in Mantra ROP node
or cache your simulation with Cache SOP before rendering