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Break SOP and detail attributes


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Hello guys, I'm new to Houdini and I'm already in love with it.

I'm following the tutorial Go Procedural - M06 | First Steps | Understanding Attributes & Variables (https://vimeo.com/41727309)[vimeo.com]

Great tutorial, everything is ok but I don't understand one thing. I use a Break SOP, which returns two detail attributes (0 and 1) that I can use with connectivity and partition SOP's to divide the shapes. The question is: where can I see the two detail attributes created by the Break SOP ?
If I middle click on the break node I can see “1 detail attribute: varmap” but if I open the Spreadsheet I can't see them.

Thank you

Ray
 

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varmap is a special attribute appearing like a "string vector". Place the File SOP node, for example. Default cube has one string in it's varmap. Typical varmap entries are: "cd -> CD", "class -> CLASS", "attribute1 -> ATTRIBUTE1". It maps attributes to custom local variables. You can use it in expressions to access corresponding attribute value, but only if node supports it. I think there is no list, but logic is that the point nodes support point variables, and so on. You can use point attribute locals in Point node, for example. Every node should support detail variables. You also can use newer @-syntax (which not existed when this tutorial was recorded), accessing attributes directly, without variables. Not sure if all use-cases of custom variables are now covered with it, but it seems so. Maybe varmap is not useful anymore.

You see the empty varmap, because something inside the Break node created an attribute with a local variable (there is another Connectivity node inside), then the attribute was deleted. Houdini does not delete an empty varmap and some nodes always add it. Just ignore or delete it with Attribute Delete or Clean node, if you don't like it.

Break SOP does not output any attributes, only group for inner surface. You could place two breaks, leaving top or bottom and assign corresponding attribute value to them. I think Connectivity is what they used in the tutorial to create attribute you need (@class). It will have 0 and 1 values across geometry, if two pieces was created by Break node. But normally it just enumerates connected pieces from zero.

 

varmap.hipnc

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