Teachable Moment ? maybe with Boolean Union

Rhino
1

Hello,

I saw Mitch’s post:

Extrude>ToBoundary - not intelligent enough… :frowning_face::

so I downloaded the file and when I was able to get the extrusion to go downward to the base - of I guess a part- so I then ran a Boolean Union on all of the objects and it worked. I repeated the process but ran intersect before the Boolean Union and it showed all of the intersection curves where a surface “meets” a surface. So here is the maybe teachable moment for me:

It is my understanding that a primary requisite for a Boolean Union to work is that the objects must intersect. So in this case the intersection is [and I am not sure this is correct word to use] a superimposition. Perhaps mathematically the area where the surfaces meet are describing the same space. Thus, when the Boolean Union command is ran the “intersection” is this “shared” space that is trimmed away and then the closed polysurface is made. Am I at least sort of on tract ?

Thank you,

Andy

2

Yes, that is essentially it. Boolean operations are simply combined Intersect/Trim/Join operations, in principle you can do them all “manually”.

https://wiki.mcneel.com/rhino/booleanfaq

3

Thank you Mitch. Much appreciated. I just had never thought about an “intersection” this way- that along with your profile curves that snap to the edge of the object + ToBoundary creates surfaces that share the same space and thus form the intersection. And yes thank you for the link to the booleanfaq page - I have read through it before and started to do so again- it just [obviously] for me takes awhile, perhaps a long while for it all to “sink in.”