Visual Basic 2005 Cookbook: Solutions for VB 2005 Programmers (Cookbooks (OReilly))

Problem

You want to work with three-dimensional coordinates as single entities.

Solution

Sample code folder: Chapter 06\ThreePoint

Create a Point3D class that works like the PointF class except that it contains a Z property in addition to X and Y.

Discussion

The following class definition is similar to the Point2D class presented in Recipe 6.12:

Public Class Point3D Public X As Double Public Y As Double Public Z As Double Public Sub New(ByVal xPoint As Double, _ ByVal yPoint As Double, ByVal zPoint As Double) Me.X = xPoint Me.Y = yPoint Me.Z = zPoint End Sub Public Overrides Function Tostring() As String Return "{X=" & X & ",Y=" & Y & ",Z=" & Z & "}" End Function End Class

The most important modification is the addition of a public Z value for the third dimension. As presented here, the X, Y, and Z properties are all Double precision, but you can easily redefine these to Single if that provides sufficient precision for your calculations, and if you want to save memory when you create large arrays of this data type.

The following code demonstrates the use of some Point3D objects. Notice how the New() function lets you create a Point3D variable with nonzero X, Y, and Z values:

Dim result As New System.Text.StringBuilder Dim distance As Double Dim point1 As Point3D Dim point2 As Point3D Dim deltaX As Double Dim deltaY As Double Dim deltaZ As Double point1 = New Point3D(3, 4, 5) point2 = New Point3D(7, 2, 3) deltaX = point1.X - point2.X deltaY = point1.Y - point2.Y deltaZ = point1.Z - point2.Z distance = Math.Sqrt(deltaX ^ 2 + deltaY ^ 2 + deltaZ ^ 2) result.AppendLine("3D Point 1: " & point1.ToString()) result.AppendLine("3D Point 2: " & point2.ToString()) result.AppendLine("Distance: " & distance.ToString()) MsgBox(result.ToString())

Figure 6-14 shows the results of calculating the distance in space between these two coordinates.

See Also

Search for "basic 3D math" on the Web for a variety of explanations and further information about this subject.