Help with intersections.

Hi all, I'm a novice with grasshopper and I must be missing something about trees. The thing is I'm stuck.

I want to intersect some planes with some curves.

in one hand, I have a couple of groups of planes, each group in a branch. in the other hand, The 2 sets of curves I want to be intersected with, which are in another tree, organized in 2 branches aswell.

I want the planes of each branch of the first tree to intersect with the curves of their corresponding branch of the second tree.

   Tree 1                                                                 Tree 2
   First branch of planes       intersect with            first branch of curves
   second branch of planes    intersect with    second branchof curves

and so on...

Note: Curves can self intersect or being cut more than once by the same plane.

I can only obtain the desired result when i do it one by one, mean, selecting each branch at a time. Can anyone help? Many thanks in advance.

Attachments:

Problem Intersections.gh, 7 KB

Replies to This Discussion

Permalink Reply by Danny Boyes on September 24, 2014 at 7:26am

Hi Gunther,

I must be missing something about trees.

most people do you are in very good company.

This would be my approach:

The top version is centered around getting the points grouped in terms of which curve they are associated with and the bottom version is the other way around i.e. which plane they are associated with.

Attachments:

ProblemIntersections_db.gh, 15 KB

Permalink Reply by Pieter Segeren on September 24, 2014 at 8:14am

Hi Gunther, hi Danny,

is cross referencing yielding the wanted results here?

Attachments:

Intersections_PSG.gh, 7 KB

Permalink Reply by ng5 Alex on September 24, 2014 at 8:30am

i thought that at first too. i believe Gunther only wants the first branch of the first tree with the first of the second etc.

something that got me confused.

wasn't these two supposed to give same results? (hope this is not lack of sleep hitting me)

cheers

alex

Permalink Reply by nikos tzar on September 24, 2014 at 8:54am

I believe the second one checks all the curves with both lists of planes. that's why there are more results.

As for the [CrossRef], the only problem imo, is the output data structure. It is just the points for each curve (each list of curves after [Pshift]) and there are no secondary branches to indicate the planes. I guess it depends on the next step of the definition...

Permalink Reply by ng5 Alex on September 24, 2014 at 10:07am

Well that is what cross reference does too. all posible compinations of the curves with planes.

Permalink Reply by nikos tzar on September 24, 2014 at 10:40am

I think cross reference creates all combinations of curves in {0} with planes in {0} and curves in {1} with planes in {1} but doesn't mix different branches (it keeps the tree structure).

Permalink Reply by ng5 Alex on September 24, 2014 at 10:55am

yes. came to my senses finally.

Permalink Reply by Danny Boyes on September 24, 2014 at 10:57am

It does. And I agree with you about the structure which is why I tend to generate the CR by myself as I can get a handle on what comes from where a bit easier.

Permalink Reply by nikos tzar on September 24, 2014 at 11:14am

True,

I tried to do this starting with [CrossRef] and then rebuilding the tree and it was such a messy definition:

By the time I got around it you had already answered with a simple and to-the-point def. :)

Permalink Reply by Pieter Segeren on September 24, 2014 at 9:03am

Hmm, if you leave the planes' tree intact (don't flatten) it does give the same results. But what is the difference between ShiftPaths and TrimTree besides the sign of the integer?...

Permalink Reply by Gunther krauss on September 24, 2014 at 9:32am

Thank you all guys. Danny, you saved my day, I'm a bit busy and overwehelmed at the moment to analyze ,understand what you did, and take the time to reply properly.

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