Graphics Bounds with jump

Hi, I am trying to make bounds for a character that can jump. I have made the character graphic into a rectangle and I have a square block in the game that the character must jump onto and I have set that as a rectangle.

How would I make it so when the character jumps onto the square block, he stays up there and then when he jumps down, and touches the ground, he stays on the ground. My current jump code is standardized; it does not detect changes in the Y-coordinate. What I have done in the jump for the character is I have made it so the Y-coordinate is increased by a certain amount and decreased by the same amount so the difference is equal to 0.

For example:

Character.LocationY += 8
Character.Location -= 8

What you'll need is collision detection. Calculate where the character will be if you were to apply the new coordinates (but don't actually assign them yet). Then, check if these new (not-yet-assigned) bounds of the character intersect with the bounds of the block/ground/whatever. If they do, the character is going to collide (but hasn't yet because you haven't assigned the new coordinates yet), so you simply set its coordinates so that it is on top of the block/ground/whatever.
If there is going to be no collision, you simply assign the new coordinates and wait for the next step (where you do the same thing).

In pseudo-code:

Code:

---

' Calculate new location
Dim newLocation = character.Location.Y + 8  'or something

' Check every obstacle (not necessarily a loop, but i can't know what kind of obstacles you have)
For Each obstacle
  If newLocation is inside obstacle Then
      ' we are going to collide, so prevent us from going inside the obstacle
      newLocation = obstacle.Location.Y
      Exit For
  End If
Next

' Assign the new location
character.Location.Y = newLocation

---

If the new location does not intersect with any obstacles, the entire For Each loop does nothing so you just assign the new location. If there is a collision though, newLocation is changed so that it stays on that obstacle and does not go inside it.

Thank you very much! I have a small problem now, if the user holds down the up arrow key after the character has doublejumped then the character will no longer doublejump, but just do one jump instead.

Here is my jump code in the form_Keydown event:

vb Code:

If doubleJump = False Then
            If e.KeyCode = Keys.Up Then
                'Resets the animation if the character was moving
                If tmrJump.Enabled = True Then
                    tmrJump.Enabled = False
                    doubleJump = True
                    characterCount = 0
                End If
 
                ' Disables movement animation
                tmrMove.Enabled = False
                'Resets character movement
                characterCount = 0
 
                ' Sets the animation image to the right direction
                If movement = "Right" Then
                    movement = "RightJump"
                ElseIf movement = "Left" Then
                    movement = "LeftJump"
                End If
                keyPressed(e.KeyCode) = True
                tmrJump.Enabled = True
            End If

vb Code:

Private Sub tmrJump_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles tmrJump.Tick
        ' Next animated frame
        characterCount += 1
        ' Causes the character to jump
        CharacterJump()
        If keyPressed(Keys.Right) Or keyPressed(Keys.Left) Then
            CharacterMove()
        End If
    End Sub

vb Code:

Private Sub CharacterJump()
        Dim newLocation As Integer = locationY
 
        Select Case characterCount
            Case 1
                newLocation -= 8
            Case 2
                newLocation -= 6
            Case 3
                newLocation -= 4
            Case 4
                System.Threading.Thread.Sleep(50)
            Case 5
                If doubleJump = True Then
                    newLocation += 8
                Else
                    newLocation += 4
                End If
            Case 6
                If doubleJump = True Then
                    newLocation += 12
                Else
                    newLocation += 6
                End If
            Case 7
                If doubleJump = True Then
                    newLocation += 16
                Else
                    newLocation += 8
                End If
            Case 8
                'Disables the animation
                tmrJump.Enabled = False
                'Resets the character to standing image
                characterCount = 0
                If doubleJump = True Then
                    doubleJump = False
                End If
 
                keyPressed(Keys.Up) = False
                If movement = "RightJump" Then
                    movement = "Right"
                ElseIf movement = "LeftJump" Then
                    movement = "Left"
                End If
 
                ' Continues previous movement on ground
                If keyPressed(Keys.Right) Or keyPressed(Keys.Left) Then
                    tmrMove.Enabled = True
                End If
        End Select
 
        If CheckForGround(newLocation) = True Then
            newLocation = 342
        End If
 
        locationY = newLocation
 
        ' Animates the character's jump
        Me.Refresh()

vb Code:

Private Sub tmrMove_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles tmrMove.Tick
        If movement = "Right" Or movement = "Left" Then
            If characterCount = 10 Then
                ' Loops the animation
                characterCount = 1
            Else
                ' Gets the next animation image
                characterCount += 1
            End If
        End If
 
        CharacterMove()
    End Sub