A simple (?) error in a Frogger-type game

[homncruse]

Okay so I've got a slight problem here. I'm coding a simple Frogger type game, and it all works fine on the first level, but on the second level, the cars move faster and some of the cars hidden off the form become activated to create more of them, to increase the difficulty.

My problem is, is after you pass the first level, the frog doesn't "die" when a car runs it over. It *will* however, die if the frog runs into a car. The first level doesn't have this problem. I think I've isolated the line of code that causes the error but I'm not sure, I've got it marked in the code.

Pasted below is all the code I believe would be relevant (it's not all of it, but only the parts that would be needed to find the problem). Thanks in advance for any help anyone can give me.

Dim Cars
Dim blnMoveL    As Boolean
Dim blnMoveR    As Boolean
Dim blnMoveU    As Boolean
Dim blnMoveD    As Boolean
Dim blnPlay     As Boolean
Dim mintPos     As Integer
Dim mintLives   As Integer
Dim mintCars    As Integer
Dim mintLevel   As Integer
Const mintFrog  As Integer = 480    'Height and Width of the frog image
Option Explicit
 
Private Sub Form_KeyDown(KeyCode As Integer, Shift As Integer)
'*snip (this code works fine, it's just the code to move the frog image)*
    CheckDeath  'Calls the CheckDeath function
    If imgFrog.Top = 0 Then AdvanceLevel    'Calls the AdvanceLevel function when frog
                                            'reaches the top
End Sub
 
Private Sub tmrCar_Timer()
    'Moves the "cars" around
    
    On Error GoTo Finish
    For Cars = 0 To mintCars
        shaCar(Cars).Left = shaCar(Cars).Left + 480
        If shaCar(Cars).Left > frmMain.Width Then
            mintPos = shaCar(Cars).Left - frmMain.Width
            If mintPos >= 0 Then
                shaCar(Cars).Left = -(mintFrog)
            End If
        End If
    Next Cars
    CheckDeath
Finish:
End Sub
 
Private Function AdvanceLevel()
    'Makes the game progressively harder
    
    Dim intTimer    As Integer
    intTimer = tmrCar.Interval
    intTimer = intTimer - 100
    If intTimer = 0 Then
        MsgBox "You've beaten the game! You are a true 'Frogger' Master!", vbExclamation, "Congratulations!"
        blnPlay = False
        tmrCar.Enabled = False
    Else
        mintLevel = mintLevel + 1
        mintCars = mintCars + 2
'Above line is the line that causes the problem I believe - when I comment it out the program works fine
        tmrCar.Interval = intTimer
        MsgBox "Proceeding to level " & mintLevel, vbOKOnly, "Level passed!"
    End If
    lblLvl = mintLevel
    StartPos    'Calls the StartPos function
End Function
 
Private Function StartPos()
    'Moves the frog image to the starting position
    
    imgFrog.Left = 4800
    imgFrog.Top = 4800
End Function
 
Private Function CheckDeath()
    'Checks to see if the frog got ran over
    
    Dim Cars2
    
    On Error GoTo Finish
    For Cars2 = 0 To mintCars
        If shaCar(Cars2).Left = imgFrog.Left And shaCar(Cars2).Top = imgFrog.Top Then
            mintLives = mintLives - 1
            If mintLives < 0 Then
                MsgBox "Game over!"
                blnPlay = False
            Else
                MsgBox "You died!" & vbCrLf & mintLives & " lives left!", vbCritical, "Splat!"
                StartPos    'Calls the StartPos function
                lblLives = mintLives
            End If
        End If
    Next Cars2
Finish:
End Function

[SLH]

Change this

If shaCar(Cars2).Left = imgFrog.Left And shaCar(Cars2).Top = imgFrog.Top Then

to this

If shaCar(Cars2).Left < imgFrog.Left + ImgFrog.Width And ShaCar(Cars2).Left + ShaCar(Cars2).Width > imgFrog.Left And shaCar(Cars2).Top < imgFrog.Top + ImgFrog.Height And ShaCar(Cars2).Top + ShaCar(Cars2).Height > imgFrog.Top Then

Basically the problem is that, as the car moves a long it may 'jump' the exact left value of the frog, so the frog would suvive. While at low speeds this would happen less frequently (or never in your case), it would happen very often unless the speed and start location of the car were multiples of the frogs start location, and move speed (or something like that).