Read Model Normal to face orientation

Submitted by fathmi on Thu, 10/08/2020 - 05:57
Forums: 
Journaling / NXOpen API

Is there any way to read the X,Y,Z orientation based on a certain normal-to-face (F8) state of a model?

Which would give a result for example: XDirection as (1,0,0) and NormalDirection as (0,0,1)

Currently I am hardcoding the coordinates for XDirection and Normal Direction, but reading these two direction by the currentnormal state would be helpful.

NXJournaling - Thu, 10/08/2020 - 06:26

The ModelingView object has a .GetAxis method that looks like it would be useful for your process. According to the API documentation:
"These are the components of the 3x3 matrix which is the rotation of absolute space which results in view space."

fathmi - Thu, 10/08/2020 - 07:38

Thanks for the idea. I found that in the documentation. Can you give me an example of the syntax? Getting squiggly line under View.GetAxis

View.GetAxis(XYZAxis.XAxis)

Regards,
MFJ

NXJournaling - Thu, 10/08/2020 - 08:35

The code below rotates the current modeling view 90 degrees about the view's Z axis.

Imports System
Imports NXOpen
Imports NXOpen.UF

Module Module115
Sub Main(ByVal args() As String)

Dim theSession As NXOpen.Session = NXOpen.Session.GetSession()
Dim theUfSession As UFSession = UFSession.GetUFSession
Dim workPart As NXOpen.Part = theSession.Parts.Work
Dim lw As ListingWindow = theSession.ListingWindow

lw.Open()

Dim myView As ModelingView = theSession.Parts.Work.ModelingViews.WorkView
Dim rotAxis As Vector3d = myView.GetAxis(XYZAxis.ZAxis)
Dim rotationAngleDegrees As Double = 90
myView.Concatenate(myView.AbsoluteOrigin, rotAxis, (Math.PI / 180) * rotationAngleDegrees)

End Sub
End Module

fathmi - Thu, 10/08/2020 - 09:40

Great. This works perfectly as expected!

Regards,
MFJ

fathmi - Thu, 10/08/2020 - 10:55

One more question,

While I am trying to read the normal axis (XYZAxis.ZAxis) I am getting correct coordinates like (0, 0, 1)

But While I am reading the Horizontal axis (XYZAxis.XAxis) I am getting the right reading for XAxis, but the vertical axis have wird value, instead of just 0. Something like this- (6.234542E-17, 0 , 1)

Do you know why? Or the slution?

Regards,
MFJ

NXJournaling - Thu, 10/08/2020 - 11:29

The value 6.23E-17 is an extremely small number (almost zero); due to how computers store floating point numbers, these small 'rounding' errors are common. If you'd like to eliminate small values near zero, I'd suggest comparing the results to a desired 'tolerance' value. Something like below (pseudocode)

Const toleranceValue as double = .0001
if abs(x) < toleranceValue then
x = 0
end if

Edit for more info:
The vec3 .Unitize method might also be helpful here. You pass in the vector and a tolerance and it will return the magnitude and the unit vector. I've not used it recently, but it might round off those small values for you.

fathmi - Thu, 10/08/2020 - 11:32

Regardless of zeroing it out it served my purpose because it is really close to zero. Thanks a lot. This will definitely help.

Regards,
MFJ

k0330 - Fri, 12/15/2023 - 09:40

Hi all,
In order to get the material (not sheet metal) thickness, I'm trying to get the edge/face which is parallel to the normal vector, and then measure their length.

I found that DatumPlane Class has the property "normal", but aside from DatumPlane.Normal how can I read the normal vector?

After I get the normal vector, I assume that I have to compare every feature with normal vector through the class NXOpen.Features.Parallel , am I right?
If so, the problem is, there is no GetFace or GetEdge in feature class...

I tried to convert the design like body and extrusion into sheet metal, and get the thickness. But how can I convert them back to their original design, if I don't want to delete the feature by mouse?

Thanks for a reply in advance!

Best regards,
Ray

NXJournaling - Fri, 12/15/2023 - 10:43

The NXOpen API has a "CheckMinimumWallThicknessBuilder" that sounds like it might be useful to you. I've not used it and could find no examples on the Siemens support site. It may require a special license. In interactive NX, use the command finder to search for "check wall thickness" and try to use the command. If it completes successfully, either it doesn't require a special license or you have access to it.

If you need the normal of a face, one way to get it is to use "AskFaceProps". Some discussion can be found in this thread:
https://nxjournaling.com/content/create-points-faces-and-get-coordinates...