frmbezier.frm

图形的裁剪是计算机图形处理中很重要的环节

VERSION 5.00
Begin VB.Form frmBezier 
   Caption         =   "Form1"
   ClientHeight    =   8985
   ClientLeft      =   60
   ClientTop       =   450
   ClientWidth     =   9615
   LinkTopic       =   "Form1"
   ScaleHeight     =   8985
   ScaleWidth      =   9615
   StartUpPosition =   3  'Windows Default
   Begin VB.PictureBox picBoard 
      BackColor       =   &H80000004&
      FillColor       =   &H0000FFFF&
      ForeColor       =   &H000000FF&
      Height          =   9000
      Left            =   0
      ScaleHeight     =   8940
      ScaleWidth      =   9540
      TabIndex        =   0
      Top             =   0
      Width           =   9600
      Begin VB.Timer Timer1 
         Interval        =   1
         Left            =   960
         Top             =   5160
      End
   End
End
Attribute VB_Name = "frmBezier"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Option Explicit
Dim Draw As Boolean
Private Type Points
X As Single
Y As Single
End Type
Dim p(100) As Points
Dim nCount%

Private Sub Form_Load()
picBoard.Scale (-100, 100)-(100, -100)
End Sub

Private Sub picBoard_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
If Button = 1 Then Draw = True
If Draw = True Then
nCount = nCount + 1
p(nCount).X = X
p(nCount).Y = Y
End If
If Button = 4 Then
Draw = False
nCount = 0
picBoard.Refresh
End If

End Sub

Private Sub picBoard_MouseUp(Button As Integer, Shift As Integer, X As Single, Y As Single)
Call DrawB

End Sub
Private Sub DrawB()
Dim i%, X!, Y!, t!, x1!, y1!
For i = 1 To nCount - 3
For t = 0 To 1 Step 0.01
X = (-t ^ 3 + 3 * t ^ 2 - 3 * t + 1) * p(i).X + (3 * t ^ 3 - 6 * t ^ 2 + 4) * p(i + 1).X + (-3 * t ^ 3 + 3 * t ^ 2 + 3 * t + 1) * p(i + 2).X + (t ^ 3) * p(i + 3).X
Y = (-t ^ 3 + 3 * t ^ 2 - 3 * t + 1) * p(i).Y + (3 * t ^ 3 - 6 * t ^ 2 + 4) * p(i + 1).Y + (-3 * t ^ 3 + 3 * t ^ 2 + 3 * t + 1) * p(i + 2).Y + (t ^ 3) * p(i + 3).Y
picBoard.Line (x1, y1)-(X / 6, Y / 6)

x1 = X / 6: y1 = Y / 6
Next
picBoard.Line (p(i).X, p(i).Y)-(p(i + 1).X, p(i + 1).Y), vbBlue
Next

End Sub