HI, learning houdini and not sure if this is a bug or me doing something wrong. I am using the measure node and having it get the area of the primitives of a torus. if I leave the attribute name to the default of “area”, I can then use a delete node after the measure node and type this “$AREA<.2” using delete by expression and it deletes the primitives correctly that have an area less than .2. If in the measure node I click the Override name button, and enter my own name, say “eric” and then type this “$ERIC<.2” into the delete expression, it gives me an error and does not work.?! It seems no matter what name I use as an override, that attribute is not useable. As a test, I put an attribCreate node after the measure node, made an attribute named “eric”, then assigned the values out of $AREA to the attribute value of eric, and then when I used “$ERIC<.2” in the delete expression it worked fine. So am I missing something here.? Or is this a bug when you try overriding the area attribute name to something custom.? One thing I notice when I middle click on the attribCreate node, it gives me a Custom Varible Mappings with eric -> ERIC. Any help is appreciated. I have just started, once again, doing some houdini tutorials… Oh and this is in H13.

you are doing it correctly - you create the attribute to assign values to it.

Hmm I figured if the measure node had the option to create a variable with a different name, then I would only have to check the override box and give it the name I wanted to use. It doesn't make sense why I would have to make my own variable and then transfer the $AREA values into this new variable to then use them with a different name.?? But it does work, so i guess I can do it that way if that is how it is suppose to work.

Thanks

E.

No worries - you're confusing Overriding with Creating; they aren't the same.

oh ok, so what would the point be of overriding since the attribute made with the overridden name doesn't seem to be directly accessible.? The tutorial I watched overrode the “area” name to “prim_area”. Is this just so you can make names you prefer or are more easily recognized and then if you want to access the data in it, you need to do the attribCreate thing I mentioned before.? It seems like an extra step since if I just leave the name to the default of “area” then I can directly access this data by way of $AREA….

E

Yes - there is no need to put the area into a differently named attribute if you don't want to, therefore you can avoid the extra step of creating it.

Ah ok cool, thanks for the info.

E

Eric Ebling
Hmm I figured if the measure node had the option to create a variable with a different name, then I would only have to check the override box and give it the name I wanted to use. It doesn't make sense why I would have to make my own variable and then transfer the $AREA values into this new variable to then use them with a different name.?? But it does work, so i guess I can do it that way if that is how it is suppose to work.

Thanks

E.

first of all Measure Sop is creating an attribute not variable
so to get the variable mapping to custom, nonstandard attribute name you need to use Attribute Create Sop to initialize variable

you can use attribute without creating a variable and I would recommend that as variables are older, slower way to do that. Have a look at the file for comparison

ah cool, the way on the right in your example file is the way I ended up doing it. But the way on the left is easier. I will use that style from now on. It is a bit confusing coming from 13+ years of working in maya. I hope to pick up houdini sooner than later.!

Thanks for the example.

E.