新建 文本文档 (3).txt

这是学习 计算方法程序设计的好教程啊。

'这是一个分别用Bezier曲线和B样条曲线进行曲线拟合的例子
'程序用VB6.0中文版编写
'例子中需要一个窗体和一个按钮（使用默认的名字）
'在本例中，黑色的线条是对坐标系上各点的直接连线
'黄色的线仅对点间连线进行近似拟合，并不通过每一个点，使用的是B样条曲线
'蓝色的线通过除第一个点和最后一个点之外的每一个点，使用的是Bezier曲线
'本程序仅供参考和演示，尚有许多不足之处，只为抛砖引玉。
'DDMM们可以借鉴，高手们也不妨一观，繁请且一笑之，尔后以不屑为此之态随心指点一二，吾恩谢之。

' ——残桓枫雪  敬上

Option Explicit
Private Type Vi      '定义点的数据结构
    x As Double
    y As Double
End Type

Dim Pts(64) As Vi, Ypts(64) As Double   '用于Bezier绘制的临时点坐标
Dim Points(3) As Vi, PointsB(3) As Vi
Dim Po(-1 To 100) As Vi

Dim CosNN(158) As Double     '用于通过Cos值查表获取角度

'Bezier计算
Private Sub calc_spline(Npts As Integer)
    Dim x As Double, dx As Double, ddx As Double, dddx As Double
    Dim y As Double, dy As Double, ddy As Double, dddy As Double
    Dim i As Integer
    Dim dt As Double, dt2 As Double, dt3 As Double
    Dim xdt2_term As Double, xdt3_term As Double
    Dim ydt2_term As Double, ydt3_term As Double
    
    dt = 1# / (Npts - 1)
    dt2 = (dt * dt)
    dt3 = (dt2 * dt)
    ' x 坐标增量计算
    xdt2_term = 3 * (Points(2).x - 2 * Points(1).x + Points(0).x)
    xdt3_term = Points(3).x + 3 * (-Points(2).x + Points(1).x) - Points(0).x
    
    xdt2_term = dt2 * xdt2_term
    xdt3_term = dt3 * xdt3_term
    
    dddx = 6 * xdt3_term
    ddx = -6 * xdt3_term + 2 * xdt2_term
    dx = xdt3_term - xdt2_term + 3 * dt * (Points(1).x - Points(0).x)
    x = Points(0).x
    
    Pts(0).x = Points(0).x
    
    x = x + 0.5
    For i = 1 To Npts
        ddx = ddx + dddx
        dx = dx + ddx
        x = x + dx
        Pts(i).x = x
    Next i
    
    ' y 坐标增量计算
    ydt2_term = 3 * (Points(2).y - 2 * Points(1).y + Points(0).y)
    ydt3_term = Points(3).y + 3 * (-Points(2).y + Points(1).y) - Points(0).y
    
    ydt2_term = dt2 * ydt2_term
    ydt3_term = dt3 * ydt3_term
    
    dddy = 6 * ydt3_term
    ddy = -6 * ydt3_term + 2 * ydt2_term
    dy = ydt3_term - ydt2_term + dt * 3 * (Points(1).y - Points(0).y)
    y = Points(0).y

    Pts(0).y = Points(0).y
    y = y + 0.5
    For i = 1 To Npts
        ddy = ddy + dddy
        dy = dy + ddy
        y = y + dy
        Pts(i).y = y
    Next i
End Sub

'Bezier控制点计算
Private Sub DRC()
Dim Tem(3) As Vi, TemB As Double, JD(1) As Double, JDT(1) As Double, t As Double, t2(1) As Double
'Bezier端点赋值
Points(0).x = PointsB(1).x
Points(0).y = PointsB(1).y
Points(3).x = PointsB(2).x
Points(3).y = PointsB(2).y
'计算Bezier控制点位置
Tem(0).x = PointsB(1).x - PointsB(0).x
Tem(0).y = PointsB(1).y - PointsB(0).y
Tem(1).x = Tem(0).x / Sqr(Tem(0).x * Tem(0).x + Tem(0).y * Tem(0).y)
Tem(0).x = PointsB(2).x - PointsB(1).x
Tem(0).y = PointsB(2).y - PointsB(1).y
Tem(1).y = Tem(0).x / Sqr(Tem(0).x * Tem(0).x + Tem(0).y * Tem(0).y)
t2(0) = 1: t2(1) = 1
For t = 0 To 158
    If t2(0) > Abs(Tem(1).x - CosNN(t)) Then
        JDT(0) = t / 100
        t2(0) = Abs(Tem(1).x - CosNN(t))
    End If
    If t2(1) > Abs(Tem(1).y - CosNN(t)) Then
        JDT(1) = t / 100
        t2(1) = Abs(Tem(1).y - CosNN(t))
    End If
Next t
JD(0) = (Sgn(PointsB(0).y - PointsB(1).y) * JDT(0) + Sgn(PointsB(1).y - PointsB(2).y) * JDT(1)) / 2
'''''
Tem(0).x = PointsB(3).x - PointsB(2).x
Tem(0).y = PointsB(3).y - PointsB(2).y
Tem(1).x = Tem(0).x / Sqr(Tem(0).x * Tem(0).x + Tem(0).y * Tem(0).y)
Tem(0).x = PointsB(2).x - PointsB(1).x
Tem(0).y = PointsB(2).y - PointsB(1).y
Tem(1).y = Tem(0).x / Sqr(Tem(0).x * Tem(0).x + Tem(0).y * Tem(0).y)
t2(0) = 1: t2(1) = 1
For t = 0 To 158
    If t2(0) > Abs(Tem(1).x - CosNN(t)) Then
        JDT(0) = t / 100
        t2(0) = Abs(Tem(1).x - CosNN(t))
    End If
    If t2(1) > Abs(Tem(1).y - CosNN(t)) Then
        JDT(1) = t / 100
        t2(1) = Abs(Tem(1).y - CosNN(t))
    End If
Next t
JD(1) = (Sgn(PointsB(2).y - PointsB(3).y) * JDT(0) + Sgn(PointsB(1).y - PointsB(2).y) * JDT(1)) / 2 + 3.14
TemB = (PointsB(2).x - PointsB(1).x) / 2.82
'Bezier控制点赋值
Points(1).x = Cos(JD(0)) * TemB + PointsB(1).x
Points(1).y = -Sin(JD(0)) * TemB + PointsB(1).y
Points(2).x = Cos(JD(1)) * TemB + PointsB(2).x
Points(2).y = -Sin(JD(1)) * TemB + PointsB(2).y
spline (vbBlue)
End Sub
'Bezier绘制
Private Sub spline(color As Long)
    Dim i As Integer
    Dim C As Long
    calc_spline (64)
    For i = 1 To 63
        Line (Pts(i - 1).x, Pts(i - 1).y)-(Pts(i).x, Pts(i).y), color
    Next i
    Line (Pts(i - 1).x, Pts(i - 1).y)-(Pts(i).x, Pts(i).y), color
End Sub

'Bezier调用
Private Sub B1(n As Integer, st As Double)
Dim t As Integer
For t = 0 To n - 4
    PointsB(0).x = Po(t).x
    PointsB(0).y = Po(t).y
    PointsB(1).x = Po(t + 1).x
    PointsB(1).y = Po(t + 1).y
    PointsB(2).x = Po(t + 2).x
    PointsB(2).y = Po(t + 2).y
    PointsB(3).x = Po(t + 3).x
    PointsB(3).y = Po(t + 3).y
    DRC
Next t
End Sub

'B样条曲线生成
Private Sub B2(n As Integer, st As Double)
    Dim l As Double, x As Double, y As Double, x0 As Double, x1 As Double, x2 As Double, y0 As Double, y1 As Double, y2 As Double
    Dim a As Integer
    For a = 0 To n - 3
        x0 = (Po(a).x + Po(a + 1).x) / 2#
        x1 = Po(a + 1).x - Po(a).x
        x2 = (Po(a).x - 2 * Po(a + 1).x + Po(a + 2).x) / 2#
        
        y0 = (Po(a).y + Po(a + 1).y) / 2#
        y1 = Po(a + 1).y - Po(a).y
        y2 = (Po(a).y - 2 * Po(a + 1).y + Po(a + 2).y) / 2#
        PSet (x0, y0), vbYellow
        For l = 0 To 1 Step st
            x = x0 + x1 * l + x2 * l * l
            y = y0 + y1 * l + y2 * l * l
            Line -(x, y), vbYellow
        Next l
    Next a
End Sub

Private Sub Command1_Click()
Dim dx As Integer, dy As Integer, t As Integer
Cls
Po(-1).x = Rnd * 40
Po(-1).y = Rnd * 300
PSet (Po(-1).x, Po(-1).y)
For t = 0 To 31
    dx = Rnd * 40
    dy = Rnd * 300
    Po(t).x = Po(t - 1).x + dx
    Po(t).y = dy
    Line -(Po(t).x, Po(t).y)
Next
Call B2(30, 0.1)
Call B1(30, 0)
End Sub

Private Sub Form_Load()
Dim t As Double, t2 As Double
For t = 0 To 1.58 Step 0.01
    CosNN(t2) = Cos(t)
    t2 = t2 + 1
Next t
End Sub



For I=0 to 999 Step -1: Money = Money + 1: Next I