Is "mineigval" only for VOPSOP??

[oldiesgoodies]

Hi

I have been trying to use mineigval and mineigvec as attributes in sop context but for some reason I cannot get the values to do anything, They show up in the details views. I also successfully import into VopSop. For some reason I cannot parse them in the Sop context.

Any ideas?

thanks

[exu]

Hi

I have been trying to use mineigval and mineigvec as attributes in sop context but for some reason I cannot get the values to do anything, They show up in the details views. I also successfully import into VopSop. For some reason I cannot parse them in the Sop context.

Any ideas?

thanks

Hi

you can use a attributecreate node...

on foamparts example you can see how... even if was VOP_SOP node...

the same is valid for ocean sop .. you can try mineigvec > myattribute for instance... also you need change the value to vector to parse right value

cheers

[oldiesgoodies]

Hi

you can use a attributecreate node...

on foamparts example you can see how... even if was VOP_SOP node...

the same is valid for ocean sop .. you can try mineigvec > myattribute for instance... also you need change the value to vector to parse right value

cheers

Thanks for the reply.

For some reason creating an attribute to parse the mineigval does work for me?

-create a float point attribute

-give a name

-I put $MINEIGVAL in the "value" slot

Am I doing it wrong?

[eloop]

Hi guys,

I have checked a new example into the google code repo that shows how to use the mineigval attribute to find where the choppy waves are self intersecting. You can download it directly (sop_mineigval.hip).

-Drew

Thanks for the reply.

For some reason creating an attribute to parse the mineigval does work for me?

-create a float point attribute

-give a name

-I put $MINEIGVAL in the "value" slot

Am I doing it wrong?

[oldiesgoodies]

Hi guys,

I have checked a new example into the google code repo that shows how to use the mineigval attribute to find where the choppy waves are self intersecting. You can download it directly (sop_mineigval.hip).

-Drew

Hi eloop

Thank you for the scene. I actually did exactly same thing but by importing "mineigval" as an attribute inside a VopSop. This is definetely a better shortcut.

My main problem is that I am having hardtime understanding the nature of these particular HOT point attributes. For example I cannot seem to be able to use "mineigval" as a standard group "filter expression".for example just putting "$MINEIGVAL>0.5" as an expression fails coooking. But if I use the expression you have in your scene file "point("../ocean1",$PT,"mineigval",0) > 0", I can create a group. My question is that are "mineigval" or other HOT attributes are some kind of implicit attributes that can be parsed only via "point" expression?

[exu]

Hi eloop

Thank you for the scene. I actually did exactly same thing but by importing "mineigval" as an attribute inside a VopSop. This is definetely a better shortcut.

My main problem is that I am having hardtime understanding the nature of these particular HOT point attributes. For example I cannot seem to be able to use "mineigval" as a standard group "filter expression".for example just putting "$MINEIGVAL>0.5" as an expression fails coooking. But if I use the expression you have in your scene file "point("../ocean1",$PT,"mineigval",0) > 0", I can create a group. My question is that are "mineigval" or other HOT attributes are some kind of implicit attributes that can be parsed only via "point" expression?

Hi, oldiesgoodies

I think that you using the "$MINEIGVAL" without declare as attribute...

i not sure but i can do the expression works here...

i'll put the example for you...

And Drew, thanks a Lot for file...

cheers

example_att.hip

Edited May 4, 2010 by exu

[oldiesgoodies]

Exu, thanks for the file. That is exactly what I needed I guess.

[exu]

Exu, thanks for the file. That is exactly what I needed I guess.

hi

you welcome...

So, just to clarify, the attribute create is a "point" class, "float" type, attribute, like Drew was done pointing directly using channels, in fact, those attribute that you can try manipulate is just a data, you need transform this data to point data, vertex data, etc, because until that, this attributes will be just this, a data... a numbers stored in a variable...

in details view of ocean sop, you can see those "data" values of mineigval, and the vector data from mineigvec as mineigvec(x,y,z) etc...

cheers

[oldiesgoodies]

exu, thanks for iterating the explanation. Seeing the mineigval values in the details pane confused me as I had taken granted that they were already promoted attributes. I did not know that I actually literally needed to pull them out of the stack and turn into attributes.

[eloop]

The way to think about it is - "mineigval" *is* a floating point "attribute" that has been added to the "points" of the geometry by the Ocean SOP. The point(...) "expression" is used to access this attribute for use in your own expressions. MINEIGVAL would be a "local variable" if it existed, but it it isn't defined by any SOPS and hence isn't available for use by expressions (ie as $MINEIGVAL). You *can* map the attributes to local variables but that is another topic that you can find out more about in the documentation and forums, look for the term "varmap", but it isn't really needed.

Remember you can type "exhelp point" in a houdini texport to read about how to use the point() expression.

-Drew

exu, thanks for iterating the explanation. Seeing the mineigval values in the details pane confused me as I had taken granted that they were already promoted attributes. I did not know that I actually literally needed to pull them out of the stack and turn into attributes.

Edited May 5, 2010 by eloop

[oldiesgoodies]

eloop, very nice in depth explanation. Thank you so much. Exu`s and your sample files were very helpul for my setup.