Line until highest berp

Hi!

I'm facing simple problem yet after few days of trying I can not solve it:

I'm making SDL line in +Z direction from point on worlds xy plane.
Line goes trough 3 floating breps(or points or curves) at random heights above xy plane.

How can I input lenght of that SDL line so that it goes till highest brep (or point or curve) ? or cut it at highest object?
Thanks!

Replies to This Discussion

Permalink Reply by David Rutten on September 27, 2015 at 4:53pm

Cut it at the top of the bottom of the highest brep? A file to experiment with would be nice.

Permalink Reply by Atis Sedlenieks on September 27, 2015 at 5:14pm

Hi David!

The file I'm working on is a bit slow and complex..
I made fast representation of the problem. Please see attached file.

Top or bottom? hmm I guess top would be more useful, because in the end lines will represent column like holders for breps.
p.s. As I mentioned, I can use lines or points instead of breps if that somehow eases the solution of the problem.

Attachments:

highest-brep-problem.gh, 10 KB

Permalink Reply by David Rutten on September 28, 2015 at 8:33am

The component that would be ideal for this problem is [Project Point], it however doesn't seem to work as advertised. Sometimes I get points on the lower of several floating boxes. I'm looking into why that's the case.

Permalink Reply by David Rutten on September 28, 2015 at 8:40am

In the meantime, the neatest alternative I can think of would be to use Mesh Ray intersection. It's quite fast, but only gives accurate results if the tops of your breps are flat.

Attachments:

highestbrepproblem.gh, 11 KB

Permalink Reply by David Rutten on September 28, 2015 at 9:58am

There was indeed a bug in the Project Point component, it failed to sometimes find the nearest object. I've fixed it so whenever the next WIP release of Rhino6 goes out (usually Tuesdays) there will be a correctly working Project component.

Permalink Reply by Atis Sedlenieks on September 28, 2015 at 11:02am

Thank you David! This works like a charm! Very nice solution!

Permalink Reply by Joseph Oster on September 28, 2015 at 7:54am

Just generate a second 'Line SDL' with length determined by the 'Z' value of the highest intersection point?

P.S. Looking at your GH, it appears at a glance that by flattening the data trees at several points, you have lost the original column/row structure, which makes the job harder?

Permalink Reply by Joseph Oster on September 28, 2015 at 8:19am

I haven't checked carefully for duplicate points and lines... but eliminating the 'Flatten' settings got me the data structure I needed:

Attachments:

highestbrepproblem_2015_Sep28a.gh, 15 KB

Permalink Reply by Atis Sedlenieks on September 28, 2015 at 11:06am

Hi Joseph,

Thank you for your help, this is very clever solution.
Problem is that I have flat list breps from another list etc.. so Davids answer is more suitable this time.

Permalink Reply by Joseph Oster on September 28, 2015 at 11:27am

Not that clever, really. But in general, you'll have better luck in GH if you keep the "history" that unflattened data lists provide - in this case, the columns and rows allow sorting of intersection results to get the highest one for each point in the original grid.

Permalink Reply by Joseph Oster on September 28, 2015 at 11:30am

You could say that the solution I used, as written, depends on a useful bug... the fact that 'BLX (Brep | Line Intersection)' works even when the line doesn't actually touch the brep.

It could be written using longer lines, of course, but this BLX result makes it possible to get the intersections even when the line is extremely short, relatively.

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