Grasshopper

algorithmic modeling for Rhino

Building lines out of set of points with circle in the middle

Hi guys,

I basically want to build a grid from the points shown in the pictures without going over the empty circle. Meaning, I want the lines to stop at the edge of the circle. What I do is just connect the list of points to a polyline, but this builds lines over the empty part (the circle). Would be great if someone can help. 

Omar

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Hi.

Hope it is of some help. Best.

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Thank you Hyungsoo Kim! That was really helpful. 

No GH/Rhino file?  Tsk, tsk...  Using Hyungsoo Kim's boundary curves, you could do it this way - gets both edge curves (in blue) and resulting surfaces:

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Hi Joseph thanks for the time and effort. I have two questions. First, would you explain the attached components? I understand what they did, but I don't understand how they perform they work. Also, yes this is the type of curves I exactly want, however how can i extract all the x-axis curves independently and all the y-cruves independently? I am building this grid for a gridshell and different members will have different properties. Thanks again 

If you look at the images I posted earlier, you can read the labels instead of having to know the icons.  The first one is 'Trim with Brep'; the 'Ci' output are the trimmed curves inside the brep, the 'Co' output are the parts outside.

The second component is 'PShift (Shift Paths').  It's been a long day and I don't want to take the time now to explain what it does.  I suggest you connect a panel to 'Ci' and look at the data tree in text form, then connect it to the 'PShift D' output to see the difference.  And/or use the 'Tree/List Viewer'.

As to extracting X vs. Y curves, yes, no problem, BEFORE 'Join'.  The 'Tree/List Viewer' is an extremely handy tool I wrote for examining geometry by path and list item.  Would be good for you to learn how to use it.  Gotta go take a walk.

To elaborate slightly...  To see what's going on, "turn the lights on", like this:

'Trim with Brep' requires a "Closed Brep" as the 'B' input, so what I did was 'Extr (Extrude)' the 'Boundary' surface by 1 unit to make a solid, then 'Move' it down (-Z) 1/2 unit so that it encapsulates the 'SubSrf', which is on the 'World XY' plane.  'Explode' in this case returns the four edges of each subsurface as separate curves, suitable for 'Trim'.

One at a time, connect a wire to the yellow panel (and/or the 'Tree' input of the 'Tree/List Viewer') from 'SubSrf', 'Explode', 'Trim Ci', 'Trim Co', 'PShift' and then 'Join' to see what is coming out of each one.

Some understanding of the data/tree structure at each step is required to get very far with Grasshopper.  It can take a lot of trial and error to "get it".  Reading and understanding as much code as possible will help.

Perfect! Thank you again, it's really helpful.

Also the tree/list viewer you made is simply BRILLIANT! As a beginner I'll always use this indeed. Makes more sense now understanding trees!

If you just want inside grid points and line connections instead of  individual grid cells, there is another way.

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Amazing! Thanks again.

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