Flying to Extent

Private Sub cmdFlyToExtent_Click()
Dim CenterX As Double
Dim CenterY As Double
Dim Distance As Double
Dim RectGeoHeight As Double
Dim RectGeoWidth As Double
Dim NormalWidth As Double
Dim NormalHeight As Double
'Dim ScreenX, ScreenY, ScreenW, ScreenH As Double
Dim FOV, FOVW, FOVH As Double
CenterX = CDbl(txtX1.Text) + ((CDbl(txtX2.Text) - CDbl(txtX1.Text)) / 2) ' The calculation can be done better, e.g. if the rectangle crosses 180 deg line etc.
CenterY = CDbl(txtY2.Text) + ((CDbl(txtY1.Text) - CDbl(txtY2.Text)) / 2) ' The calculation can be done better, e.g. if the rectangle crosses 180 deg line etc.
RectGeoWidth = CoordSys.GetDistance(CDbl(txtX1.Text), CDbl(txtY1.Text), CDbl(txtX2.Text), CDbl(txtY1.Text))  ' Calculates the width on the top line of the rectangle (should be max between top and botom)
RectGeoHeight = CoordSys.GetDistance(CDbl(txtX1.Text), CDbl(txtY1.Text), CDbl(txtX1.Text), CDbl(txtY2.Text))  ' Calculates the Height on the left line of the rectangle (Same as the right)
Render.GetRenderRect ScreenX, ScreenY, ScreenW, ScreenH
If (ScreenW > ScreenH) Then
    FOVW = Rad(Plane.FieldOfView)
    FOVH = Tan(Atn(FOVW / 2) * (ScreenH / ScreenW)) * 2
Else
    FOVH = Rad(Plane.FieldOfView)
    FOVW = Tan(Atn(FOVH / 2) * (ScreenW / ScreenH)) * 2
    
End If
If (RectGeoWidth = 0) Or (RectGeoHeight / RectGeoWidth > ScreenH / ScreenW) Then
    Distance = RectGeoHeight / 2 / Tan(FOVH / 2)
Else
    Distance = RectGeoWidth / 2 / Tan(FOVW / 2)
End If
'***Top View***
Plane.FlyTo CenterX, CenterY, 0#, Distance, 0#, -90#, "FlyToLocation"
'***For Angled View remove comment****
'***Dim Angle As Double
'***Angle = 30
'***Plane.FlyTo CenterX, CenterY, 0#, Distance / Cos(Rad(Angle)), 0#, -90# + Angle, "FlyToLocation"
'***For Angled View remove comment****
End Sub