Forums Technical Discussion Dynamic Attribute 'declaration' in vex

Dynamic Attribute 'declaration' in vex

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BabaJ
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Hello,

Does anyone know if it's possible to create attributes ‘dynamicaly’ in vex?

Just for simplicities sake, say in a point wrangle create dynamic number of attributes that are each an array of values.

Where the user sets the number of arrays created with either 1,2,3 or 4 and so on etc. with a parameter slider.

It's not important what the dynamicly created arrays are named ie., I don't need this to be ‘displayed’ or available for the user end.

Just so I can access them distinctly according to how many were created.

According to documents vex currently does not support multi-dimensional arrays, which if they did I could easily implement what I want by using an array of arrays.

I'm putting this question out there before I make an RFE, in case there is a way to do the equivalent of a multi-dimensional array.

Thanks for any help.
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malbrecht
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Maybe this video is of some help?



Marc
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Out of here. Being called a dick after having supported Houdini users for years is over my paygrade.
I will work for money, but NOT for "you have to provide people with free products" Indie-artists.
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https://www.marc-albrecht.de [www.marc-albrecht.de]
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BabaJ
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Thanks malbrecht…I'll have a look at it.
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BabaJ
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Hmmm…I think I should have made my original post shorter to just asking if there is a ‘workaround’ to accomplish arrays of arrays in vex.

This video doesn't do that…but I do see why you suggested it, as it does relate to how I ‘framed’ my original post.

Thanks for your input malbrecht.
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tamte
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very convoluted question, I guess it depends on the final use
you can always create points with array attribute
create as many points you want addpoint() => first dimension
each can have different array as an attrib setpointattrib() => second dimension
and of course you can as well create many attribs instead of points setpointattrib() (or addpointattrib() prior to H16), depending on needs
Tomas Slancik
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jlait
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If you want ragged array-of-arrays, and you just need to store them in attributes and retrieve them, you can use a pair of array attributes. One stores the lengths of your sub-arrays, the other raw data.

float @arraydata[];
int @arraylen[];
int curstart = 0;
foreach (int len; arraylen)
{
   float a[] = @arraydata[curstart:curstart+len];
   // Work on a[]
   curstart += len;
}

We do something similar to export normal arrays to OpenCL as they are effectively array-of-arrays from the viewpoint of an OpenCL kernel.

Rather than length, you can also store the absolute start allowing random access. Length can then be specified separately, or implied as a difference between starts.

This is all basically re-inventing memory management using a normal float array as just an arbitrary memory container. So all squarely falls under “workarounds”; which is why there already are RFEs for proper arrays-of-arrays in VEX.
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