Public Shared Function CRC32 ( 
	currentRemainder As UInteger,
	value As Double
) As UInteger

Imports Rhino.DocObjects
Imports Rhino
Imports Rhino.Geometry


<System.Runtime.InteropServices.Guid("62dd8eec-5cce-42c7-9d80-8b01fc169b81")> _
Public Class AnalysisModeOnCommand
  Inherits Rhino.Commands.Command
  Public Overrides ReadOnly Property EnglishName() As String
    Get
      Return "cs_analysismode_on"
    End Get
  End Property

  Protected Overrides Function RunCommand(doc As RhinoDoc, mode As Rhino.Commands.RunMode) As Rhino.Commands.Result
    ' make sure our custom visual analysis mode is registered
    Dim zmode = Rhino.Display.VisualAnalysisMode.Register(GetType(ZAnalysisMode))

    Const filter As ObjectType = Rhino.DocObjects.ObjectType.Surface Or Rhino.DocObjects.ObjectType.PolysrfFilter Or Rhino.DocObjects.ObjectType.Mesh
    Dim objs As Rhino.DocObjects.ObjRef() = Nothing
    Dim rc = Rhino.Input.RhinoGet.GetMultipleObjects("Select objects for Z analysis", False, filter, objs)
    If rc <> Rhino.Commands.Result.Success Then
      Return rc
    End If

    Dim count As Integer = 0
    For i As Integer = 0 To objs.Length - 1
      Dim obj = objs(i).[Object]()

      ' see if this object is alreay in Z analysis mode
      If obj.InVisualAnalysisMode(zmode) Then
        Continue For
      End If

      If obj.EnableVisualAnalysisMode(zmode, True) Then
        count += 1
      End If
    Next
    doc.Views.Redraw()
    RhinoApp.WriteLine("{0} objects were put into Z-Analysis mode.", count)
    Return Rhino.Commands.Result.Success
  End Function
End Class

<System.Runtime.InteropServices.Guid("0A8CE87D-A8CB-4A41-9DE2-5B3957436AEE")> _
Public Class AnalysisModeOffCommand
  Inherits Rhino.Commands.Command
  Public Overrides ReadOnly Property EnglishName() As String
    Get
      Return "cs_analysismode_off"
    End Get
  End Property

  Protected Overrides Function RunCommand(doc As RhinoDoc, mode As Rhino.Commands.RunMode) As Rhino.Commands.Result
    Dim zmode = Rhino.Display.VisualAnalysisMode.Find(GetType(ZAnalysisMode))
    ' If zmode is null, we've never registered the mode so we know it hasn't been used
    If zmode IsNot Nothing Then
      For Each obj As Rhino.DocObjects.RhinoObject In doc.Objects
        obj.EnableVisualAnalysisMode(zmode, False)
      Next
      doc.Views.Redraw()
    End If
    RhinoApp.WriteLine("Z-Analysis is off.")
    Return Rhino.Commands.Result.Success
  End Function
End Class


''' <summary>
''' This simple example provides a false color based on the world z-coordinate.
''' For details, see the implementation of the FalseColor() function.
''' </summary>
Public Class ZAnalysisMode
  Inherits Rhino.Display.VisualAnalysisMode
  Private m_z_range As New Interval(-10, 10)
  Private m_hue_range As New Interval(0, 4 * Math.PI / 3)
  Private Const m_show_isocurves As Boolean = True

  Public Overrides ReadOnly Property Name() As String
    Get
      Return "Z-Analysis"
    End Get
  End Property
  Public Overrides ReadOnly Property Style() As Rhino.Display.VisualAnalysisMode.AnalysisStyle
    Get
      Return AnalysisStyle.FalseColor
    End Get
  End Property

  Public Overrides Function ObjectSupportsAnalysisMode(obj As Rhino.DocObjects.RhinoObject) As Boolean
    If TypeOf obj Is Rhino.DocObjects.MeshObject OrElse TypeOf obj Is Rhino.DocObjects.BrepObject Then
      Return True
    End If
    Return False
  End Function

  Protected Overrides Sub UpdateVertexColors(obj As Rhino.DocObjects.RhinoObject, meshes As Mesh())
    ' A "mapping tag" is used to determine if the colors need to be set
    Dim mt As Rhino.Render.MappingTag = GetMappingTag(obj.RuntimeSerialNumber)

    For mi As Integer = 0 To meshes.Length - 1
      Dim mesh = meshes(mi)
      If mesh.VertexColors.Tag.Id <> Me.Id Then
        ' The mesh's mapping tag is different from ours. Either the mesh has
        ' no false colors, has false colors set by another analysis mode, has
        ' false colors set using different m_z_range[]/m_hue_range[] values, or
        ' the mesh has been moved.  In any case, we need to set the false
        ' colors to the ones we want.
        Dim colors As System.Drawing.Color() = New System.Drawing.Color(mesh.Vertices.Count - 1) {}
        For i As Integer = 0 To mesh.Vertices.Count - 1
          Dim z As Double = mesh.Vertices(i).Z
          colors(i) = FalseColor(z)
        Next
        mesh.VertexColors.SetColors(colors)
        ' set the mesh's color tag 
        mesh.VertexColors.Tag = mt
      End If
    Next
  End Sub

  Public Overrides ReadOnly Property ShowIsoCurves() As Boolean
    Get
      ' Most shaded analysis modes that work on breps have the option of
      ' showing or hiding isocurves.  Run the built-in Rhino ZebraAnalysis
      ' to see how Rhino handles the user interface.  If controlling
      ' iso-curve visability is a feature you want to support, then provide
      ' user interface to set this member variable.
      Return m_show_isocurves
    End Get
  End Property

  ''' <summary>
  ''' Returns a mapping tag that is used to detect when a mesh's colors need to
  ''' be set.
  ''' </summary>
  ''' <returns></returns>
  Private Function GetMappingTag(serialNumber As UInteger) As Rhino.Render.MappingTag
    Dim mt As New Rhino.Render.MappingTag()
    mt.Id = Me.Id

    ' Since the false colors that are shown will change if the mesh is
    ' transformed, we have to initialize the transformation.
    mt.MeshTransform = Transform.Identity

    ' This is a 32 bit CRC or the information used to set the false colors.
    ' For this example, the m_z_range and m_hue_range intervals control the
    ' colors, so we calculate their crc.
    Dim crc As UInteger = RhinoMath.CRC32(serialNumber, m_z_range.T0)
    crc = RhinoMath.CRC32(crc, m_z_range.T1)
    crc = RhinoMath.CRC32(crc, m_hue_range.T0)
    crc = RhinoMath.CRC32(crc, m_hue_range.T1)
    mt.MappingCRC = crc
    Return mt
  End Function

  Private Function FalseColor(z As Double) As System.Drawing.Color
    ' Simple example of one way to change a number into a color.
    Dim s As Double = m_z_range.NormalizedParameterAt(z)
    s = Rhino.RhinoMath.Clamp(s, 0, 1)
    Return System.Drawing.Color.FromArgb(CInt(Math.Truncate(s * 255)), 0, 0)
  End Function
End Class