Boolean Addition Problem

I'm new to grasshopper so bear with me. I did a little bit of reading (an hr) on this issue, and trying to find a solution in intro videos... nothing worked

I have several boxes that are placed on grid points... Some oriented lengthwise in X some lengthwise in Y.

The rectangles appear fine but only the lengthwise ones in Y will join with each other, not the ones in the X direction.

I can Boolean add them in Rhino... in either direction... no problems

I tried numerically increasing the length of the X lengthwise ones to the point that I can see the overlap in Rhino... they still wont add in grasshopper.

Any suggestions greatly appreciated.

The picture shows the grid and subsequent boxes made for x and y ... the rhino side shows that the ones in x remain separate.

Replies to This Discussion

Permalink Reply by Brian Harms on September 20, 2017 at 4:57pm

gotta upload dem files

Permalink Reply by Matt Beng on September 20, 2017 at 10:19pm

Hi Brian,

I'm attaching the grasshopper file...

apologies... I didn't think it would be needed... figured it was something common I've overlooked.

the two unions in the bottom right near the large text box are what's giving me problems

Attachments:

Help with boxes.gh, 18 KB

Permalink Reply by Hyungsoo Kim on September 21, 2017 at 12:52am

It's pretty basic, but the boxes in the separate data tree branches can not be united using "Boolean Union" until you flatten data tree structure.
You need to understand the Data Tree before you do any more work.
Anyway, is this what you want?

Attachments:

Helpwithboxes_re.gh, 23 KB

Permalink Reply by Matt Beng on September 21, 2017 at 12:32pm

You're right... I do need a better understanding of the data tree...

Flattening it did work, Thank you!

In follow up, I went back again used the parameter viewer to get a better sense of what's going on (not all that helpful here), it did show 7 branches, which go to 1 when flattened...

My confusion now is why did it work for one group and not the other group before either of them were flattened?

Permalink Reply by Joseph Oster on September 21, 2017 at 1:32pm

You're right... I do need a better understanding of the data tree...

Does this help? Before and after 'SUnion' images, the first pair (without 'Flip') has no effect - do you understand why? The second pair uses 'Flip Matrix'; see the difference? Hint: 'SUnion' (like many GH components) works only on lists and treats each branch as a separate list.

'Tree/List Viewer' is a utility I wrote and use all the time to examine trees of geometry.

Attachments:

Helpwithboxes_2017Sep21a.gh, 36 KB

Permalink Reply by Matt Beng on September 21, 2017 at 9:06pm

Very helpful... Way more than I expected! The list concept makes sense.

And thanks for the upload with the tree viewer incorporated...

it explicitly shows how grasshopper is trying to join the boxes in one direction only (I tried it on both box commands to compare), like trying to join columns in a matrix even when the boxes are only touching other boxes in rows... it sees the boxes in the column as not touching... and doesn't join them.

I also used the tree viewer on the flattened box output... shows that grasshopper is looking at all of the pieces in a grid format like a matrix where the sequential count for a column carries over row by row and then continues to the next column.

Thanks Again Very Much.

-Matt

Permalink Reply by Joseph Oster on September 21, 2017 at 9:58pm

Literal visualization can be so helpful, eh? Cheers.

Permalink Reply by Joseph Oster on September 22, 2017 at 7:09am

P.S. I hope it's also very clear that without posting your model, this kind of response, specific to you, is impossible. In most cases, almost any response without a model is just a waste of time.

Permalink Reply by Joseph Oster on September 21, 2017 at 8:12am