Create line by length and angle

Scripting
1

Is there a way to create a line from a point of a defined length and angle?

2

Look in the Rhino help under ‘Accurate modeling’ [sic] or ‘Accurate drawing’.

3

I’m looking to do it with a script.

4

Do you mean a command macro, rhinoscript or python?

5

Yes. I would like to create the line in Rhino using a starting point, length and angle using Python.

6

I could write a function to do it but was looking for a command if it exists.

7

An angle between the line and what? In what plane is the angle measured? XY, XZ, YZ or an arbitrary plane?

This would make more sense if you use start point, a vector (direction) and length, like the standard Grasshopper Line SDL component. Otherwise your spec is too vague, angle alone is indeterminate.

8

XY plane, a starting point, a length and an angle.

9

I guess you mean the angle in the XY plane between the X direction and the line? It wasn’t easy but I’m glad that much is clarified…

10

Ok. I realize my question was too general. I guess what I am looking for are other ways to create a line without simply supplying predefined end points. For example when one is drawing in the top view and creating a series of lines you can specify the line length and then pick a direction on screen to place the line without knowing exactly where the end point should be. It places the line and maintains the length. So, using python code, I pick a start point (0,0,0 for example), define a length and specify an angle in relation to x. For example x+ would be 0 and the angles would 0 to 360 off of that. Or perhaps it has to be specified as a vector normal in relation to the XY plane.

I have already constructed a function to do this and maybe that’s the way it needs to be done. I was just probing for other ways to create lines other than specifying two end points.

11

A line is always determined by two points… In fact a RhinoCommon line object is exactly that.

If you look here, you can see the RhinoCommon methods available to construct a line:

https://developer.rhino3d.com/api/RhinoCommon/html/T_Rhino_Geometry_Line.htm

Ohterwise, you can always use trig to get the other endpoint of the line, or, just make a line along one axis and rotate it…

import rhinoscriptsyntax as rs
import scriptcontext as sc
import Rhino

def MakeAngledLine():
    spt=rs.GetPoint("Pick start point")
    if not spt: return
    
    length=rs.GetReal("Length?")
    if length is None: return
    
    ang=rs.GetReal("CCW Angle in degrees? (0=X Axis)")
    if ang is None: return
    
    lvec=Rhino.Geometry.Vector3d.XAxis
    lvec.Rotate(Rhino.RhinoMath.ToRadians(ang),Rhino.Geometry.Vector3d.ZAxis)
    line=Rhino.Geometry.Line(spt,lvec,length)
    sc.doc.Objects.AddLine(line)
    sc.doc.Views.Redraw()
MakeAngledLine()
2 Likes
12

One of those should work for me. Thanks.

13

and one more just to make sure you did not miss it…

-_Line 0 10 <60

1 Like
14

This is a command line entry I assume. I’ll try it. Thanks!!!

15

Yes, and the single “0” is a shortcut for 0,0,0 on the active CPlane. You can replace that with _Pause if you want to set the start point manually:
-_Line _Pause 10 <60

16

This does mostly what I am trying to do but it is just constraining the line to a 60 degree angle. I still need a point to finish the command.

17

You can “hardcode” that with a macro, but a proper script like Mitch posted, would be more comfortable if you want to alter the values.
-_Line _Pause r10,0,0 _SelNone _SelLast _Rotate r-10,0,0 60 _Enter

18

Hi @eric.bunn,

You can also use some trigonometry:

import System
import Rhino
import scriptcontext as sc

def PointFromAngleDistance(point, theta, hypotenuse):
    adjacent = System.Math.Cos(theta) * hypotenuse + point.X
    opposite = System.Math.Sin(theta) * hypotenuse + point.Y
    return Rhino.Geometry.Point3d(adjacent, opposite, point.Z)

p0 = Rhino.Geometry.Point3d(0.0, 0.0, 0.0)
angle = Rhino.RhinoMath.ToRadians(27.6)
distance = 15.4

p1 = PointFromAngleDistance(p0, angle, distance)

line = Rhino.Geometry.Line(p0, p1)
sc.doc.Objects.AddLine(line)
sc.doc.Views.Redraw()

– Dale

19

Thank you Dale!!