How do I detect collision with spawned objects? - vb.net

Question

Public Class Form1
Dim i As Integer 'integer for spawning
Dim maxball As Integer = 50 'max ball able to be created
Dim RateX(maxball) As Integer 'rate of movement
Dim RateY(maxball) As Integer 'rate of movement
Dim ball(maxball) As PictureBox 'spawned ball is a picture box
Dim rnd As New Random 'random number generator
Dim rndLoc As Integer 'random locatino generator
Dim Loc As Point 'location is a point on the screen
Dim create As Integer 'integer to create new balls
Dim score As Integer = 0 'score is 0 but can increase
'move the ball
Private Sub moveball()
'For Each ball(ec) In ball
For i As Integer = 0 To create - 1
If ball(i).Left <= pbArena.Left Then 'bounce off left side
RateX(i) *= -1
End If
If ball(i).Right >= pbArena.Right Then 'bounce off right side
RateX(i) *= -1
End If
If ball(i).Top <= pbArena.Top Then 'bounce off top
RateY(i) *= -1
End If
If ball(i).Bottom >= pbArena.Bottom Then 'bounce off bottom
RateY(i) *= -1
End If
'====================================================================================================================================================
ball(i).Left += RateX(i) 'moves the ball horizontally
ball(i).Top += RateY(i) 'moves the ball vertically
'====================================================================================================================================================
Next
End Sub
'create the ball
Private Sub createball()
If create <= 50 Then '50 is max amount to
create += 1 'add 1 to create
ball(i) = New PictureBox 'ball is a picture box
ball(i).Size = New Size(45, 45) 'set size
ball(i).BackColor = Color.Red 'set color
'====================================================================================================================================================
ball(i).Top = rnd.Next(pbArena.Height - ball(i).Height) 'sets random y
ball(i).Left = rnd.Next(pbArena.Width - ball(i).Width) 'sets random x
'====================================================================================================================================================
RateX(i) = rnd.Next(-4, 4) 'random X direction/speed
RateY(i) = rnd.Next(-4, 4) 'random Y direction/speed
'====================================================================================================================================================
Me.Controls.Add(ball(i)) 'actually add teh ball
ball(i).BringToFront() 'bring to front so arena isn't in front
i += 1
End If
End Sub
'commands for when you touch black box
Private Sub pbTarget_MouseEnter(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles pbTarget.MouseEnter
pbTarget.Top = rnd.Next(pbArena.Height - pbTarget.Height) 'sets random y
pbTarget.Left = rnd.Next(pbArena.Width - pbTarget.Width) 'sets random x
'====================================================================================================================================================
'scoring system
score = score + 1
lblScore.Text = score
createball() 'creates a new ball
End Sub
'what happens when the timer ticks
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
moveball() 'every timer tick the ball will move IF its created
ball(i) = New PictureBox 'ball is a picture box
End Sub
End Class
This is my code so far. Each time the mouse intersects with the target (which is a picture box) is moves. I am replicating this game. http://www.lewpen.com/game/ I have used an array to spawn red squares on the form. I want to be able to detect when my mouse enters them. I know how to do this with picture boxes, but these are all spawned objects called ball(i). Thanks for the help!

Answer 1

It sounds like you want to know how to add an event handler to a dynamically created control. these are all spawned objects called ball(i) but they are all just pictureboxes. You can add event handlers when you create the balls (pictureboxes)
Private Sub createball(BallIndex As Integer)
Dim ball As New PictureBox 'ball is a picture box
' give it a name so we can find it
' ball index is PASSED to avoid sloppy global vars
ball.Name = "Ball" & BallIndex.ToString
' etc
Me.Controls.Add(ball)
AddHandler ball.MouseEnter, AddressOf BallMouseEnter
Elsewhere, you'd add the code for the event:
Private Sub BallMouseEnter(sender As Object, e As EventArgs)
' your code here
End Sub
Since the balls exist as controls in the Controls collection there is really no reason to keep a reference to them in an array. If you name them "Ball1", "Ball2" you can make them move by referencing them by name:
Me.Controls(ballname)
Where BallName would be "Ball" & index.ToString and index would be the ball/picturebox to move (like the i variable). EDIT More info:
Private Sub moveballS()
Dim ball As PictureBox
' loop thru ballS
For n As Integer = 0 To BallCount
' current ball from name
ball = Me.Controls("Ball" & n.ToString)
' your code here
If ball.Left <= pbArena.Left Then
' etc
End If
' you CAN just reference them in controls(),
' but it is wordy:
If Controls("Ball" & n.ToString).Left <= pbArena.Left Then
' etc
End If
Next n
End Sub
Another way to track them is just a List(Of String) to store the name, but that is equally unneeded if you can get them by name from Controls() as above:
Dim ballList As New List(Of String)
' when you create a ball:
ballList.Add(ball.Name)
to get a control reference:
For n As Integer = 0 To ballList.Count - 1
ball = Me.Controls(ballList(n))
' etc
It can be a bad idea to create a separate reference to dynamically created controls (like an array) since that ref can prevent the object from being disposed of if/when you reset or start over and are deleting balls/pictureboxes.