SrfPts Command in Rhino 8 _not 3 points but 4 minimum control points? -

Rhino
1

Hello,

Something new appeared in Rhino 8
When Creating a triangle surfade form 3 point (minimum for defining a planar surface). modifing then this surface by using _pointsOn command show me not 3 but 4 control points.

Geometrically speaking, the ability to control a planar surface with only 3 points (and not more) is essential for building some basic geometries.
In Rhino 7, this was possible.

Is there a way to solve the problem? Any variable to disable?

Thanks in advance

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2

As far as I know SrfPt has always behaved this way… I checked as far back as V5 and it does the same thing. The workaround would be to make a triangle (polyline), Explode and make an EdgeSrf from the 3 lines.

3

@Vincent_Blanc-Taille Are you remembering EdgeSrf (not SrfPt) from V7? EdgeSrf creates an untrimmed 3 side surface when the inputs are 3 lines or curves. If the the input is 3 lines (with coincident ends) then the lines are planar and the result of EdgeSrf will be an untrimmed 3 side surface wth 3 control points.

1 Like
4

Here is a quickie script that will make a 3 point surface with one singular side.

"""Makes a 3 point surface with one singular side.  Singularity will be at the
third point chosen.  Script by Mitch Heynick 29.03.2"""

import rhinoscriptsyntax as rs
import scriptcontext as sc
import Rhino

def Make3PtSrf():
    msg1="First corner of surface"
    msg2="Next corner of surface"
    pts=rs.GetPoints(True,False,msg1,msg2,max_points=3)
    if not pts or len(pts)!=3: return
    tol=sc.doc.ModelAbsoluteTolerance
    brep=Rhino.Geometry.Brep.CreateFromCornerPoints(pts[0],pts[1],pts[2],pts[2],tol)
    if brep:
        sc.doc.Objects.AddBrep(brep)
        sc.doc.Views.Redraw()
Make3PtSrf()
1 Like
5

Proceedure without using a script.

SrfPt
Select first point
Select second point
Select third point
Select third point again
Enter

Result will be a 3 side surface with 3 control points and one singular side.

6

Yes, that’s essentially what the script does (uses the third point also as the fourth point). You don’t actually need the Enter for your procedure, it finishes as soon as the 4th point is picked.

7

Guys,

You are impressive guys!

I dont know how to set up any script but I see that this last proceedure is actually working perfectly.

Thanks you so much!

8

Here is some basic info on that:

https://wiki.mcneel.com/rhino/macroscriptsetup

Things for V8 will be a little different as far as making toolbar buttons are concerned, I am waiting for the toolbar UI stuff to stabilize a bit more and then I will start writing a new page for V8.