Attributes

[stig_olsen]

Hi,

 

Im new to Houdini and having a hard time understand how attributes works, even though I have seen a lot of tutorials about it.

Hope some of you can explain this a bit better for me after reading what does not make sense to me.

 

Im supposed to direct my fractured chunks to go in the directions I want them to.

 

In my project I have used $TX2-$TX, $TY2-$TY, $TZ2-$Z to make a velocity direction between orignal points from a grid to some adjusted points in the air. This is supposed to give me a velocity direction. When turning on the normals I can see a visualization of the direction between the points so this totally makes sense. This is done with the edit and point sop.

This "v" for velocity is also visible as v(x), v(y) and v(z) in my digital view so I guess this means I have a velocity or what?

 

The next to steps is what I dont understand:

 

I need to go intro the voronoifracture sop, and check "create name attribute and write "v" in the name prefix. Why?

I also need to to into DOPS, choose my RBD fractured object, and check "inherit velocity from point velocity" Why?

 

I dont understand the logic in those two thing? Can you please help me explain?

 

I have attached my project if my explanation is far off.

 

Stig

 

 

 

attributes.hipnc

[LPriest]

I havn't looked at your scene but:

 

The name prefix is arbitary, its just a prefix to a string attribute called name that the rbdfracture object will use to partition your SOP into seperate DOP objects to simulate.

Maybe they are calling it v because the tutorial is looking at inheriting velocities...

 

The voronoi is probably copying the velcoity attribute from your fracture points to your pieces, when creating your dop objects the the initial velocities can be calculated directly from these values.

If the 'inherit velocity from point velocity' is not checked the default values of the rbdfracture object will be used.

 

 

Houdini has this kind of convinence built in all over the place, often if you have an attribute with same name as a parameter you want to vary houdini will use this when calculating in DOPS or DOPS. Examples of this are setting the point value kangular over the points of a wire object will multiply with the settings in your wire object, or if you write a point float attribute 'height' which varies on your points this will be used as your height per point in the mountain SOP.