Question

如何做一个vb小球沿余弦曲线运动

（1）一个实心小红球沿cos（x）的曲线匀速运动
（2）速度和曲线区间可以由用户自行设置
（3）运动过程可随时停止和启动
（4）能够将图片以图片形式保存

Answer 1

你这里面，在复制代码的时候没法进行格式化，凑合看吧，按照下面的程序设计，把下面的代码赋值过去应该就能用了。

界面设计如下：

一个Picturebox，两个textbox，一个Timer，三个command按钮 

运行效果： 

代码如下：

Dim a() As String '存放区间的值

Dim b As Single '存放圆球的实时x坐标

Dim n As Boolean    '区间改变时从起点开始移动

Private Sub Command1_Click()

Timer1.Interval = Val(Text1.Text) * 1000    '设置移动速度

Timer1.Enabled = True

a = Split(Text2.Text, ",")

n = True

If n Then

b = Val(a(0))

End If

Call DrawTheXY

Picture1.Circle (b, Cos(b)), (a(1) - a(0)) / 50, RGB(255, 0, 0)

End Sub

Private Sub Command2_Click()

Timer1.Enabled = False

Picture1.Circle (b, Cos(b)), (a(1) - a(0)) / 50, RGB(255, 0, 0)

End Sub

Private Sub Command3_Click() '保存图片

SavePicture Picture1.Image, "D:\1.jpg"

End Sub

Private Sub Form_Load()

Picture1.AutoRedraw = True

Picture1.FillStyle = 0

Picture1.FillColor = RGB(255, 0, 0)

End Sub

Function DrawTheXY()    '自定义函数，根据给定的区间画出余弦曲线

Picture1.Cls

If Val(a(0)) < 0 And Val(a(1)) > 0 Then

Picture1.AutoRedraw = True

Picture1.Scale (Val(a(0)) * 1.1, 2)-(Val(a(1)) * 1.1, -2)

Picture1.Line (Val(a(0)) * 1.05, 0)-(Val(a(1)) * 1.05, 0)

Picture1.Line (0, 1.5)-(0, -1.5)

Picture1.Line (Val(a(1)) * 1.05, 0)-(Val(a(1)) * 1, 0.1)

Picture1.Line (Val(a(1)) * 1.05, 0)-(Val(a(1)) * 1, -0.1)

Picture1.Line (0, 1.5)-(-Val(a(1)) * 0.03, 1.3)

Picture1.Line (0, 1.5)-(Val(a(1)) * 0.04, 1.3)

Picture1.CurrentX = -Val(a(1)) * 0.1

Picture1.CurrentY = 1.5

Picture1.Print "Y"

Picture1.CurrentX = Val(a(1)) * 1.05

Picture1.CurrentY = -0.1

Picture1.Print "X"

Picture1.CurrentX = Val(a(1)) * 0.03

Picture1.CurrentY = -0.05

Picture1.Print "0"

For i = Val(a(0)) To Val(a(1)) Step 0.001

Picture1.PSet (i, Cos(i))

Next i

Else

If Val(a(1)) <= 0 Then

Picture1.AutoRedraw = True

Picture1.Scale (Val(a(0)) * 1.1, 2)-(Val(a(1)) * 0.9, -2)

Picture1.Line (Val(a(0)) * 1.05, 0)-(Val(a(1)) * 0.95, 0)

For i = Val(a(0)) To Val(a(1)) Step 0.001

Picture1.PSet (i, Cos(i))

Next i

End If

If Val(a(0)) >= 0 Then

Picture1.AutoRedraw = True

Picture1.Scale (Val(a(0)) * 0.9, 2)-(Val(a(1)) * 1.1, -2)

Picture1.Line (Val(a(0)) * 0.95, 0)-(Val(a(1)) * 1.05, 0)

For i = Val(a(0)) To Val(a(1)) Step 0.001

Picture1.PSet (i, Cos(i))

Next i

End If

End If

End Function

Private Sub Text2_Change()

n = True

End Sub

Private Sub Timer1_Timer() '控制小球的移动

b = b + (Val(a(1)) - Val(a(0))) * 0.001

If b >= Val(a(1)) Then

b = Val(a(0))

End If

n = False

Picture1.Cls

Call DrawTheXY

Picture1.Circle (b, Cos(b)), (a(1) - a(0)) / 50, RGB(255, 0, 0)

End Sub