side scroller without bitblt

[nameJack]

I attached a sidescroller program in which I did not use any API
or whatsoever to write this

please help me on the collision detection
and gravity as well
i dont mind using a bit of API

theres this icon 'dont walk' in it
the thing are not suppose to walk oever it
u can jump over it and stand over it
any help?

[Janus]

Nice job.
You can try using the IntersectRect API function, it's fast, and does a great job for collision detection.

[nameJack]

Well
can u help me with the code?
its pretty confusing i know
is it possible to add gravity in it?
thanks a lot

[Janus]

I'd be glad to help.
Gravity isn't that hard, as long as you don't mind using Singles to store your Y and Y Velocity.

Feel free to email me, or we can work via the message board, or via ICQ (130863581).

[Janus]

Public Declare Function IntersectRect Lib "user32" (lpDestRect As RECT, lpSrc1Rect As RECT, lpSrc2Rect As RECT) As Long
Public Type RECT
Left As Long
Top As Long
Right As Long
Bottom As Long
End Type

' For forms using ScaleMode 1 - Twips
Public Function RectFromControlTwips(Ctl As Control) As RECT
Dim CtlRect As RECT
With CtlRect
.Left = Ctl.Left \ Screen.TwipsPerPixelX
.Top = Ctl.Top \ Screen.TwipsPerPixelY
.Right = (Ctl.Left + Ctl.Width) \ Screen.TwipsPerPixelX
.Bottom = (Ctl.Top + Ctl.Bottom) \ Screen.TwipsPerPixelY
End With
End Function

' For forms using ScaleMode 3 - Pixels
Public Function RectFromControl(Ctl As Control) As RECT
Dim CtlRect As RECT
With CtlRect
.Left = Ctl.Left
.Top = Ctl.Top
.Right = Ctl.Left + Ctl.Width
.Bottom = Ctl.Top + Ctl.Bottom
End With
End Function

[nameJack]

thanks

[Janus]

To check for collisions, try something like this:

Dim NewRect as RECT
If IntersectRect(RectFromControlTwips(Image1), RectFromControlTwips(Image2), NewRect) Then
' Collided
End If

[nameJack]

i get error for using

.Bottom = Ctl.Top + Ctl.Bottom

It seems that my image had no properties of a bottom
how to cure that?

btw,
which one is use for gravity?
and u told me not to store single x and y variable
can u tell me how to do that?
thanx

[Jotaf98]

Hum I'd do it the old VB way

If Img1.Left + Img1.Width >= Img2.Left And _
  Img1.Top + Img1.Height >= Img2.Top And _
  Img1.Left <= Img2.Left + Img2.Width And _
  Img1.Top <= Img2.Top + Img2.Height Then
    'We've got a collision!
End If

You can do this:

1) Remember the position (Left/Top) of the image BEFORE you move it, using variables
2) Move the image
3) If it collides with a platform, move it back to the position you saved in the variables

[Jotaf98]

Btw, you should have 1 variable (boolean) for each key; in the KeyDown event, you set it to True; in the KeyUp event, you set it to False. Then, in the Timer, for example, just check if the Left key is being pressed (the boolean variable is True) and move the image to the left