MeshRay error in Python

Scripting
1

Hi, I am running into an issue trying to execute the MeshRay function from Rhinocommon in Python. Specifically I am getting the error message 'float' object is not iterable on the following line of code:

intParm, intFace = Rhino.Geometry.Intersect.Intersection.MeshRay(someMesh, someRay)

I think the issue arises when trying to get the second output of the function, specifically the list of mesh faces that the ray intersects. However this works fine:

intParm = Rhino.Geometry.Intersect.Intersection.MeshRay(someMesh, someRay)

I can’t even think of an alternative way to call the function and still get the mesh face list, it is quite perplexing.

2

Hi Scott,

The second MeshRay method overload you are trying to call has an out parameter. Out parameters are not returned by method, but rather “filled” when supplied to the method call:

import System
import Rhino
import clr

# define someMesh, someRay

faceIndexArray = clr.StrongBox[System.Array[System.Int32]]()
t = Rhino.Geometry.Intersect.Intersection.MeshRay(someMesh, someRay, faceIndexArray)
if t >= 0:
    faceIndexL =  list(faceIndexArray.Value)
    print faceIndexL
3

Thanks! this worked great.

Where is this documented though? I found something very similar in an IronPython documentation for working with .NET libraries but it had a different Syntax that didn’t work in Rhino’s Python. I’m not sure where some of this syntax you are showing is coming from.

4

You can find more info on ironpython.net/documentation. Check the explicit call on that page. clr.Reference is an equivalent to clr.StrongBox.
For typed arrays, check this page.