Straight Loft puzzles (facade triangulation)

Well friends

This is still my very first attempt in GH (it's "part" of the code attached here: http://www.grasshopper3d.com/forum/topics/a-geodetic-exoskeleton-tower).

Using straight Loft and then decomposing the brep in quads and then getting the triangles is rather a very common way of thinking with regard similar solutions.

Problem is that the straight Loft doesn't work as expected (at least to me):

See 2 versions of the code (use Saved Views as well):

with profile rotation (OK):

and without (some profiles are not taken into account)

Spot the Scale values (the 2 lists with Input/Output) used on these profiles (values they appear "distinguishable" enough to me)

Is this a tolerance issue ? or what?

Other than that I can't get the gist of the Graph Mapper (how exactly works in edit mode? it's a mystery to me).

Best, Peter

Attachments:

TRIANGULATE_AN_OPEN_BREP_1.ghx, 938 KB

Replies to This Discussion

Permalink Reply by Jon Mirtschin on February 10, 2012 at 3:28am

You're asking for a singular ruled surface over the height of these profiles?

As it's failing, I'd suggest it's not geometrically possible. If you want each level to have a ruled surface, loft between adjacent curves (I didn't adjust or check your model after this, but I think it's the same effect as nominating a tight loft in your model).

Attachments:

TRIANGULATE_AN_OPEN_BREP_1 loft adjacent curves.ghx, 991 KB

Permalink Reply by peter fotiadis on February 10, 2012 at 3:46am

Hi Jon

NO I'm not after a singular ruled surface - obviously impossible (thus the straight loft option...meaning a polysurface).

I only say that straight Loft doesn't "use" all the profiles and as a result the polysurface instead of "connecting" all adjacent curves ... omits some of them (doc.tolerance ?? who knows?).

See the very same problem on my latest posts here (v7) : ( http://www.grasshopper3d.com/forum/topics/a-very-strange-pline-actu... ).

See the solution as well (lofting pairs of lines):

Permalink Reply by Jon Mirtschin on February 10, 2012 at 4:12am

But then use the tight option for loft instead of straight (if the loft must pass exactly through the profile curves). If you read the rhino help maybe it can explain the difference better than me ;-)

Permalink Reply by peter fotiadis on February 10, 2012 at 4:35am

No, tight doesn't address the problem, since we need to decompose the thing...anyway...forget it (for the moment) and wait for version v8 that address the puzzle and creates a nice(?) planar glazing array of cables, fasteners and other useless stuff.

PS: one issue brings the other :

There's some components that respect the tree and others that do whatever they want.

For instance imagine 23 line sets that belong to 3 branches (the facade profiles). If you apply Divide curv (say with 7 divisions) you expect to get back 23*7 points in 3 branches....not the case I'm afraid.

However if you apply Eval Curv with just one value for t > you get 23 points in 3 branches.

Moral: more red Russian vodka required (+ a decent cigar)

Permalink Reply by peter fotiadis on February 11, 2012 at 3:54am

Forget my comments about components that don't "respect" the tree (blame ouzo with breakfast - NEVER again).