Image Collision
Verify if two images will hit if you do move one of the image of X left and X right. Very useful when programming actions, sports or rpg games.
Original Author: Mathieu Tremblay
Inputs
MovingImage = the image to move
moveLeft = the Left movement of the MovingImage
moveTop = the Top movement of the MovingImage
StaticImage = the image you don't want to hit
Returns
Return if the two images would hit ( True or False ).
Side Effects
The MovingImage will automaticly move if you don't erase the two folling lines of code:
MovingImage.Left = MovingLeft
MovingImage.Top = MovingTop
Code
Public Function CollisionMovingImage(MovingImage As Variant, moveLeft As Integer, moveTop As Integer, Optional StaticImage As Variant) As Boolean
On Error GoTo ErrHandler:
'If one of the parameters is not found or
'some error happen in the function, it will
'then exit.
Dim MovingLeft, MovingRight, MovingTop, MovingBottom As Integer
'The Moving variables are used to get infos about the
'MovingImage.
MovingLeft = MovingImage.Left + moveLeft
MovingRight = (MovingImage.Left + moveLeft) + MovingImage.Width
MovingTop = MovingImage.Top + moveTop
MovingBottom = (MovingImage.Top + moveTop) + MovingImage.Height
Dim okLeft, okTop As Boolean
' okLeft is use to see if the MovingImage has a point
' of its width in commun with the StaticImage. The
' okTop is used to see if it happens with the height.
okLeft = True
okTop = True
'They are set to true by default to allow the moving
'of the MovingImage if there is no StaticImage.
If IsMissing(StaticImage) = False Then
'Execute the verification only if the
'StaticImage argument is used.
Dim StaticLeft, StaticRight, StaticTop, StaticBottom As String
'The Static variables are used to get infos about
'the StaticImage.
StaticLeft = StaticImage.Left
StaticRight = StaticImage.Left + StaticImage.Width
StaticTop = StaticImage.Top
StaticBottom = StaticImage.Top + StaticImage.Height
Dim i As Integer
'Verify if the MovingImage has a point
'of its width in commun with the StaticImage.
For i = StaticLeft To StaticRight
If (MovingLeft = i) Or (MovingRight = i) Then
okLeft = False
End If
Next i
'Verify if the MovingImage has a point of
'its height in commun with the StaticImage.
For i = StaticTop To StaticBottom
If (MovingBottom = i) Or (MovingTop = i) Then
okTop = False
End If
Next i
'Don't move the MovingPicture if there
'would be a collision.
If okTop = False And okLeft = False Then
'Return true because the two objects
'would have a commun point.
CollisionMovingImage = True
GoTo ErrHandler:
End If
End If
'Move the MovingImage...
'You could remove the two following lines if you
'wanted the function to only tell you if there would
'be a collision or no.
MovingImage.Left = MovingLeft
MovingImage.Top = MovingTop
'Return false because there have been no collision
CollisionMovingImage = False
ErrHandler:
End Function
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