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#1 Posted : Sunday, March 15, 2009 8:03:58 PM(UTC)

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Joined: 3/9/2008(UTC)
Posts: 554

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I am using Vector Objects in my project. After VObject was roteted I want to reset this rotate angle back to 0.

The following code allows to calculate the angle between horizon and VObject using Transformation matrix. After you get the angle you can transform VObject matrix and back VObject angle to 0.

'  Reset Angle button
Private Sub _resetButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles _resetButton.Click
    If _mlv.CurrentDesigner.VObjects.Length > 0 Then
        Dim obj As VObject = _mlv.CurrentDesigner.VObjects(0)
    End If
End Sub

' Reset Angle function
Private Sub ResetObjectAngle(ByVal obj As VObject)
    Dim angle As Single = GetVObjectAngle(obj)

    Dim bounds As RectangleF = obj.GetTransformedVObjectBounds()
    Dim point As New PointF(bounds.Left + bounds.Width / 2, bounds.Top + bounds.Height / 2)

    If angle <> 0 Then
        obj.Transform.RotateAt(-angle, point, Drawing2D.MatrixOrder.Append)
    End If
End Sub

Private Shared Function GetVObjectAngle(ByRef obj As VObject) As Single
    Dim skyline As PointF = New PointF(1000, 0)
    Dim objSkyline(1) As PointF
    objSkyline(0) = New PointF(1000, 0)

    Return CalcAngle(skyline, objSkyline(0))
End Function

' Calculates angle between 2 specified vectors.
Private Shared Function CalcAngle( _
   ByVal v0 As System.Drawing.PointF, _
   ByVal v1 As System.Drawing.PointF) As Single

    Dim dotProduct As Single = v0.X * v1.X + v0.Y + v1.Y
    Dim vLengthProduct As Single = CalcLength(v0) * CalcLength(v1)

    If vLengthProduct < 0.01 Then
        Throw New ApplicationException("Ups, div by zero error...")
    End If

    Dim result As Single = _
      CType(Math.Acos(dotProduct / vLengthProduct) / Math.PI * 180, Single)

    Dim vecProduct As Single = v0.X * v1.Y - v0.Y * v1.X
    If vecProduct < 0 Then
        result = 360 - result
    End If

    Return result
End Function

' Calculates length of the specified vector.
Private Shared Function CalcLength(ByVal v0 As System.Drawing.PointF) As Single
    Return CType(Math.Sqrt(v0.X * v0.X + v0.Y * v0.Y), Single)
End Function

Edited by moderator Monday, May 28, 2012 8:32:56 PM(UTC)  | Reason: Not specified

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