Nurbs -
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‎2018-04-09 10:05 PM
I was trying to take an adventures step to understand nurbs GDL commands, but then I found out that the GDL manual is pretty confusing ... so here goes my questions:
1- Nurbssurface
degree_u: degree of surface in the u parameter directiona- I understand the concept of U,V & W, but how many Knot points in UV must I use to define correctly a nurbs surface ?
degree_v: degree of surface in the v parameter direction
nu, nv: number of control points in u and v directions, greater than degree (not less than order) of then surface in given direction
b- Suppose that the surface is a rectangular shape with a slight curve, does this mean I have to take 4 points :
(0,0), (0,1), (1,1), (1,0)?
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‎2018-04-13 12:36 AM
I have got the answer from another source
The U & V value that were mentioned in the manual are that of the surface as whole and not at a specific loction.
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‎2018-04-10 03:59 PM
A general definition of nurbs is:
#knots in knot vector = control points + order
assuming rectangle (points at corners) and quadratic order = 5 knots/vector as in:
(0,0,1,2,2)
minimum control points would be at corners unless you wanted more control - than add point in centers.
(0,0,0), (1,0,0), (0,1,0), (1,1,0) i believe that Archicad also requires a weight.
Windows 11 - Visual Studio 2022; ArchiCAD 27
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‎2018-04-10 05:35 PM
The only way I think it is possible to figure it out now is to make some nurbs object in Rhino and import it as an object to AC (I am planning to do it but the lack of time prevents form it ;P)
Piotr
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‎2018-04-10 08:26 PM
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‎2018-04-11 05:02 PM
Moonlight wrote:Since ver 20 it creates the series of nurbs related comands in 3d script - however the input from Rhino has to be a nurbs object.
Already tried that, the model changes to a mesh object
Piotr
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‎2018-04-12 12:17 AM
by Piotr DobrowolskiNo it doesn't, I have just tried that again after seeing your comment. It changes the body to a mesh using VERT, Edge & Pgon{2}Moonlight wrote:
Already tried that, the model changes to a mesh object
Since ver 20 it creates the series of nurbs related comands in 3d script - however the input from Rhino has to be a nurbs object.
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‎2018-04-13 12:36 AM
I have got the answer from another source
The U & V value that were mentioned in the manual are that of the surface as whole and not at a specific loction.
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‎2018-04-13 06:43 AM
For any interested: attached is a nurbs file for a simple cube of degree 1 (linear).
It was quickly made in Rhino and imported very well in to Archicad.
As you would see adding more degrees to make a true nurb would really complicate even a simple object.
size = X: 9.438, Y: 10.686, Z:9.197
The zip file contains the Rhino , GDL, Object, pln files plus the text of the 3Dcode which would probably be of primary interest.
I see that the conversion to GDL code was fairly direct and illustrates the usage of the Archicad GDL Code.
Critical to the code is the direction of the various faces, surfaces etc. I found that just too confusing -- Don't have the patience, And there's no explanation in Archicad other than it has to be done.
I found it much easier to just configure in Rhino and than import -- You may want to do it directly in Archicad -- Good Luck,
Windows 11 - Visual Studio 2022; ArchiCAD 27
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‎2018-04-14 02:26 PM
How did you manage to save this object as nurbs in ArchiCAD ?
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‎2018-04-14 05:31 PM
IN Archicad in a new project -- use File- open -- select Rhino 3D model
use fit window as the object may be in left field.
Then select and open Library & Object -- save selection as -- object
Can't help with Rhino as I'm not familar with it -- I prefer FormZ.
FYI: I talked with tech support and no one in USA TS is familar with the nurb GDL commands -- said It was added just to import Rhino files. But its pretty straight forward except I can't figure out the direction of the cutting curves. Edges and Faces -- OK. if you figure that out let me know. I might make a video later but this is so tedious to do, i doubt it's not worth just doing in Rhino -- Wish they supported FormZ?
Windows 11 - Visual Studio 2022; ArchiCAD 27