Hi,

has someone an idea how I could make planar four-sided figures on the surface of this three sided dome.

All in the same plane or each on a different plane ?
Trim each line between them
Draw a rectangle by 3 points,select curves of the polygons and project them on the plan


or make the same for each polygon , select curves of the polygons and project them on the plan

Hallo FP,

in this way, that the quads form the dome.

I´ve done it with another form. But in this case, it seems to be more complicated.

AH ok I see! :)

Use the LineWeb script! I had don't remember of it at the first message! ;)
http://moi3d.com/forum/display.php?webtag=MOI&msg=3666.10

http://moiscript.weebly.com/lineweb-toile-daraigneacutee.html Video in French bu very visual ! ;)

Thank you FP,

but I have no idea, how to use the lineweb in this case.

I'm just working on quadrangulate free form on MoI to use it in ParacloudGem...
My way is wrapping a squared panel on the free form with the flow v3beta tool. If I want straight lines for the quad, I export in OBJ with 180° to straighten any spline.
But the quad are not planar... :(

You can easily make planar quad in the second dome because the geometry is made with parallel scaled ellipses, so you can divide each ellipse in the same way and find parallel lines to make planar quads. But in your first shape, I cant see the geometrical way you model it. Is there any scaled curves ? There are arc or free splines ?... Send the file to see ;) [edit : oops... I haven't seen in the first post... sorry]

Object made with the first process and :

< Send the file to see
File is on the first post ;)

Did you use only arcs ? So, where are centers and radius ?
I think I find something, but can really made a process because I'm not sure of the geometry...

More easy :)

Draw a Plan 3 points
Use The CPlane (auxiliar Plane) on this plane
Select that you want planar
Use the Edit Frame for resize in View Front
Reset the CPlane
Close holes by Blend

That's all ;)

here i have taken all the surface but you can take only quadrangles that you want!

But seems planar a curvated surface is not the good thing to make in this case!
Make that from the begining with the Line WEB!

Meanwhile I think, it cannot function.

Hi Rudl, it's quite difficult to place planar quadrilaterals along curved outlines because it's so easy for the 4 points to be warped a little bit. It's most natural for only 3 points to define a plane instead of 4 points.

Have you looked at Rhino's paneling tools? That's a set of tools in Rhino for helping to generate planar quadrilaterals on walls and things like that like you're trying to do here. I think they've had a developer specially focused on working on it for the past few years now. http://wiki.mcneel.com/labs/panelingtools

For doing it manually without any kind of helper tool like that, I guess you'll probably need to do something like initially start with 3 sided areas since you know those will be planar and then figure out what you want to adjust in order to bring 2 adjacent triangular planes into a single planar quad. I believe that the paneling tools has various mechanisms where they go through that kind of a process and automatically adjust points for you or something like that.

Since MoI uses the same file format as Rhino it should be easy to use your surface with Rhino's paneling tools, you can just open up the same 3DM file in Rhino and use those tools on it directly I think.

- Michael

Hi Rudl, so maybe one feasible manual drawing strategy would be to get some lines drawn in at the 4th quad corner coming off of it like a surface normal, then you can draw in a plane through 3 points and use Construct > Curve > Isect to intersect it with that line, that will then give you the adjusted 4th planar point for one quad, then repeat this across the surface.

I'll see if I can give you an illustration of this way.

- Michael

Hi Rudl, so to start with I'd probably delete many of the curves you've got there since they'll get in the way and also you'll probably want to make sure that the points you have are right on the surface so that you'll be able to get "surface normal snap". Many of the points that you've got there currently are just slightly off of the surface and so you won't get surface normal snap when drawing a line starting on them.

So for this point here for example I just deleted it and placed a new one using "onsrf" object snap so I knew that it was on the surface:



With the point on the surface, you can then draw a line from it and get "surface normal" snap like this:



Here's another view of the same line:



So there I enabled the "Both sides" mode for the line, each one of these lines will be a kind of leveling reference line that you can use to find the 4th planar point starting with just 3.

Once you have drawn in the surface normal line you can then delete or hide the point, because we will be generating a new planarized point that will be pretty close by it and so you don't want to get them confused.

The way to find the 4th point is to start by making a 3 point plane, which you can do either by Draw solid > Plane > 3 points or another way is to draw in 3 lines and select them and run Construct > Planar. Probably hide the big base surface before doing this so it's easier to select and work with the planar fragment.


Now you will have something like this - a triangular plane and a vertical line off to the side a bit:




You now need to extend the plane until it runs into that vertical surface normal line - probably the easiest way to do that is to just grab the corner edit frame handle which I've circled in red above and just drag that off to the side until your plane is big enough to where you see the vertical line being divided by it like this:




Now you can generate the 4th quad point by selecting both that stretched out plane and also the vertical line at the same time and running Construct > Curve > Isect - that will calculate the intersection between the plane and the line and create a point object there. Now you have 4 points that are on one single plane and you can draw lines between them and use Construct > Planar on those lines to build a planar quad face:




So anyway this method might be general enough for you to proceed with creating planar quads across the area that you want, start by placing points directly on the surface, maybe one by one delete each one you've currently got and replace it using "onsrf" object snap in the same general location. Then draw in surface normal lines and delete the on-surface points. Then it's possible to start with one 3sided plane and get an adjusted planarized 4th point by extending the plane and generating the intersection point.

Let me know if this does not do what you need. Basically paneling tools in Rhino would probably automate a bunch of this for you.

- Michael

Hi Michael, thank you for your comprehensive answer. I will read it later.

Meanwhile I think, I came nearer to a solution. I draw lines and projected them on the surface. The result is very good, accept the ends of the projected lines, the red circles shows it, should meet themselves where the arrow is. Any suggestions?



Rudl

Hi Rudl, the problem with the projection method that you show there is that while yes you're getting 4 sided areas, the sides are all curved and the 4 corner points are not going to be all one one single plane...

Is a result like that ok for what you need or do you need to have 4-sided planar pieces which is what I thought you were looking for?

- Michael

No, it was not that what I´m looking for.
I thought, this could be the way how planar quads should be located. But they don´t want.

Rudl

Hi Rudl, yeah if you need planar quads then you'll just can't really use any method that generates curved shapes like that projection does, things that are all curvy will not be planar at the same time...

You probably need to think more about starting some piece of the construction with a plane itself and then generate more pieces by something like intersecting that plane with other parts, that way you know that the result is planar. That's basically how the method that I wrote above works, I think that may work for you...

- Michael

In fact you want something like to cut a diamond ?

.....In fact you want something like to cut a diamond ?

This is a good comparision