Can I reference Mass Properties in an Expression?

adrian_vlzkz

Could find anything on the help, basically trying to see if I can use "system" values when writing an Expresion for a Variable. (Mass, Volume, Density...)

brucebartlett

I don't think so but this would be and handy

Jake_Rosenfeld

@adrian_velazquez

It would be pretty easy to make a "measure volume" custom feature which sets a variable to the volume of a selected part.  Density (and hence, mass) are trickier because FeatureScript does not have access to the material assignment of a part.  What is the overall goal here?

adrian_vlzkz

The goal is to Drive a shape (a couple of dimensions) based on a specified weight.

Jake_Rosenfeld

@adrian_velazquez

Maybe I misunderstood.  Do you just want to set a variable to "3 m^3" or "10 kg", or do you want to set a variable to the measured volume/mass/density of an existing part? 

adrian_vlzkz

I want to set a Variable to 1kg then have my dimensions driven by an expression that uses the Volume. Density would be needed in my expression to know my target Volume

Jake_Rosenfeld

This should be possible using an "any" variable

billy2

Can you pass the context to a variable's function?

function() { return evVolume(context, {"entities" : qEverything(EntityType.BODY)}); }



Hoping this will return the volume of all parts at the position it's in the tree.

ilya_baran

No, we deliberately block usage of context in expressions (because it can lead to some really unintuitive results -- what if the user does an opSomething call in a parameter?) but a custom feature can easily do thiis.

shouldNotBePosting

Honestly, referring to featurescript from the variable function may not be necessary, I still had to lookup evVolume. If you're at the need level, just write a featurescript, I can do it in 3 lines of code and have greater functionality with featurescript vs. a 1 line function call.

I'm going to write a featurescript to set these variables. This is all that needs to be done. Adrian's request is still valid. Why aren't these already being set? The benefit with a feature script is that you can ask which parts to include in a volume calculation which is useful. The globals that you set in a partstudio will have to be "all".

shouldNotBePosting

 

ilya_baran

@shouldNotBePosting
Not sure if I understand your question, but mass properties can be expensive to compute -- we should not be doing it without the user asking.

billy2

Sorry, I've got too many computers and too many accounts.

@ilya_baran thanks, I think I have this under control. I'm going to have a featurescript write the volume to a variable using a featurescript.