Tomas Slancik

goldleaf
You can't cache a Switch LOP to USD, it has no representation in USD. So whatever is switching your LOP is causing the ROP to not write out the USD.

I assume the expectation is that exporting a sequence with animated switch into a single .usd (or caching) will behave exactly the same as if you run USD Stitch of individual frames, which have different switched stages

if it doesn't behave this way there needs to be some warning as that would not be intuitive

Object Merge will take geometry from local space of the Cube, optionally applies Transform and brings it into local space of the Sphere

so you can think about those transform modes in terms of what transform is added to the geo you are merging into your sphere and then obviously separate Sphere's object level transform will also be applied, since that geo lives within the sphere


None - will not apply any additional transform
Into This Object - a delta transform from Sphere to Cube is applied
Transform Into Specific Object - a delta transform from Reference Object to Cube is applied

which in other words means that the transform delta of the Cube geometry from the Sphere Object will be the same as transform delta of the Cube Object from the Reference Object

this can be useful if you have a hierarchy of Objects and you want to merge all of them into another Object relative to their Root Object for example

Harry_S
As for "understanding the logic behind VEXpressions" - its too small example for me to study the logic on it. i dont understand how my line of code was "transformed" into this nonsense that I have in "Generated code" tab =/

But I understood the logic in your expressions, although Houdini help does not tells you that you can use "set" command like you did, it only says that "set" is used in forms like "vector set(float v1, float v2, float v3))" or that you can use "self" with an index like "self.x". I think I will learn all that stuff by looking on peoples expressions on forums etc.

I just dont understand why point node demands to redefine all elements of vector when you change one of them and wrangle does not require that. And yes when I look at the code generated

Attibute Expression SOP is just a wrapper around Attribute Wrangle SOP
it takes your single line "expression" and injects it into a wrangle to build a valid snippet code which initializes self variable for you to use and is assuming your line is producing a final value that's assigned back

so essentially a wrapper for some usecases, mostly to replace old Point SOP that relied on hscript expressions to modify per point attributes and is now discontinued
I personally prefer using Wrangles rather than Attribute Expression even for simple assignments

also set() is just a VEX function that you can use to build vector or arrays with, and assignment to a vector attribute expects vector, I used set() to create that vector value