Hi to all.
In .NET environment I'm seeking a method to detect the orientation (rotation angle) of blocs and solids in 3D space through the X,Y and Z axis.
There is a object.method? or a procedure?
Thanks to all
Hi Luigi,
There is no direct way to retrieve this information from the API, however concerning BlockReferences you could use the "BlockReference.BlockTransform" property that returns a 3d matrix and compute those angles (called Euler angles) yourself.
An example of such a computation is illustrated by the code below. Unfortunately it applies to Inventor, but you will be able to invoke equivalent methods from the ARX.Net API on the Matrix3d object.
Concerning Solid3d, this class doesn't expose a transformation property or equivalent information, so unless you created the solid aligned with (X,Y,Z) axis and keep track of any transformation that is applied to it (by keeping a total transformation matrix up-to-date each time the solid is transformed), you won't be able to determine anything about its orientation in space.
Here is the Inventor solution to retrieve the matrix angles:
If we look at the properties of a part in an assembly, we can see the x,y,z coordinates and angles. How can we get the angle values via API?
There is no direct way to get these angles via API. However, it should be possible to get them via the 4x4 homogeneous transformation matrix.
t11 t12 t13 tx
t21 t22 t23 ty
t31 t32 t33 tz
0 0 0 1
tx, ty, and tz represent the translations along x, y, and z directions.
From the values of other elements of the matrix, one can get the Eulerian/ Cardanian angles.
Public Function Acos(value) As Double Acos = Math.Atn(-value / Math.Sqr(-value * value + 1)) + 2 * Math.Atn(1) End Function Sub CalculateRotationAngles(ByVal oMatrix As Inventor.Matrix, ByRef aRotAngles() As Double) Const PI = 3.14159265358979 Const TODEGREES As Double = 180 / PI Dim dB As Double Dim dC As Double Dim dNumer As Double Dim dDenom As Double Dim dAcosValue As Double Dim oRotate As Inventor.Matrix Dim oAxis As Inventor.Vector Dim oCenter As Inventor.Point Set oRotate = ThisApplication.TransientGeometry.CreateMatrix Set oAxis = ThisApplication.TransientGeometry.CreateVector Set oCenter = ThisApplication.TransientGeometry.CreatePoint oCenter.X = 0 oCenter.Y = 0 oCenter.Z = 0 ' ' Choose aRotAngles[0] about x which transforms axes[2] onto the x-z plane ' dB = oMatrix.Cell(2, 3) dC = oMatrix.Cell(3, 3) dNumer = dC dDenom = Sqr(dB * dB + dC * dC) ' Make sure we can do the division. If not, then axes[2] is already in the x-z plane If (Abs(dDenom) <= 0.000001) Then aRotAngles(0) = 0# Else If (dNumer / dDenom >= 1#) Then dAcosValue = 0# Else If (dNumer / dDenom <= -1#) Then dAcosValue = PI Else dAcosValue = Acos(dNumer / dDenom) End If End If aRotAngles(0) = Sgn(dB) * dAcosValue oAxis.X = 1 oAxis.Y = 0 oAxis.Z = 0 Call oRotate.SetToRotation(aRotAngles(0), oAxis, oCenter) Call oMatrix.PreMultiplyBy(oRotate) End If ' ' Choose aRotAngles[1] about y which transforms axes[3] onto the z axis ' If (oMatrix.Cell(3, 3) >= 1#) Then dAcosValue = 0# Else If (oMatrix.Cell(3, 3) <= -1#) Then dAcosValue = PI Else dAcosValue = Acos(oMatrix.Cell(3, 3)) End If End If aRotAngles(1) = Math.Sgn(-oMatrix.Cell(1, 3)) * dAcosValue oAxis.X = 0 oAxis.Y = 1 oAxis.Z = 0 Call oRotate.SetToRotation(aRotAngles(1), oAxis, oCenter) Call oMatrix.PreMultiplyBy(oRotate) ' ' Choose aRotAngles[2] about z which transforms axes[0] onto the x axis ' If (oMatrix.Cell(1, 1) >= 1#) Then dAcosValue = 0# Else If (oMatrix.Cell(1, 1) <= -1#) Then dAcosValue = PI Else dAcosValue = Acos(oMatrix.Cell(1, 1)) End If End If aRotAngles(2) = Math.Sgn(-oMatrix.Cell(2, 1)) * dAcosValue 'if you want to get the result in degrees aRotAngles(0) = aRotAngles(0) * TODEGREES aRotAngles(1) = aRotAngles(1) * TODEGREES aRotAngles(2) = aRotAngles(2) * TODEGREES End Sub
This code example is based on the theory from http://kwon3d.com/theory/euler/euler_angles.html
Philippe Leefsma
Developer Consultant
Developer Technical Services
Hello Philippe,
I tried your code in Autodesk Inventor. But I get everytime a wrong value for the z-angle. It is 180 opposite - for example it should be 180 and it is 0 or -180 and is 0
Thanks
Georg
@GeorgK - you should start a new thread for this. Anyways, be aware that not all programs use the Z-axis as "world up". Its very common for mechanical design programs like Inventor to use Z-axis as "depth" and Y-axis as "up". You need to construct the transform relative to the space you are working with.
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