PureBASIC and scrolling

[Olliv]

Index
Previous example

@Demivec

You are right. Thank you for you to loose time to explain me different problems or compatibility.
After these corrections, I updated the first code. (I didn't remove the alpha channel neither the using of sprite 3D. Because sprites 3D get specific transformations which could be very useful for the future effects. If we remove also alpha channel and sprite 3D, processing ressources are different and allow us to use parallax which is executed in the 3rd code.)

Even if it's not electronic, this scrolling could be a good occasion to create a game, studying the basic mechanism.

Code: Select all

; >>>>  /!\ ONLY WITH DX7 (PB4.40)  <<<<

Procedure RedStone(X.I, Y.I, W.I, H.I)
    Box(X + 0, Y + 0, W - 1, H - 1, RGBA(255, 0, 0, 255) )
    Box(X + 1, Y + 1, W - 1, H - 1, RGBA(64, 0, 0, 255) )
    Box(X + 1, Y + 1, W - 2, H - 2, RGBA(128, 0, 0, 255) )
EndProcedure

Procedure CreateTileTest(No.I, Wi.I, He.I)
  CreateImage(No, Wi, He, 32)
  StartDrawing(ImageOutput(No) )
    DrawingMode(#PB_2DDrawing_AlphaChannel)
    Box(0, 0, Wi, He, RGBA(0, 0, 0, 0) )
    DrawingMode(#PB_2DDrawing_AlphaBlend)
    For K = 0 To 1
      For J = -2 To 2 Step 2
        For I = 0 To 1
          RedStone((I + J) * 8, I * 8 + K * 16, 16, 8)
        Next
      Next
    Next
  StopDrawing()
  CreateSprite(No, Wi, He, #PB_Sprite_Texture | #PB_Sprite_AlphaBlending)
  StartDrawing(SpriteOutput(No) )
    DrawAlphaImage(ImageID(No), 0, 0)
  StopDrawing()
  CreateSprite3D(No, No)
  Start3D()
    DisplaySprite3D(No, 0, 0)
  Stop3D()
EndProcedure

Procedure CreateTileMono(No.I, Wi.I, He.I, Coef.I)
  CreateImage(No, Wi, He, 32)
  StartDrawing(ImageOutput(No) )
    DrawingMode(#PB_2DDrawing_AlphaChannel)
    Box(0, 0, Wi, He, RGBA(0, 0, 0, 0) )
    DrawingMode(#PB_2DDrawing_AlphaBlend)
    For I = 0 To 15
      Color = RGB(0, Coef * 8 + (7 - I / 2), Coef * 16 + (15 - I) )
      Box(0, I * 2, Wi, 2, RGBA(Red(Color), Green(Color), Blue(Color), 255) )
    Next
  StopDrawing()
  CreateSprite(No, Wi, He, #PB_Sprite_Texture | #PB_Sprite_AlphaBlending)
  StartDrawing(SpriteOutput(No) )
    DrawAlphaImage(ImageID(No), 0, 0)
  StopDrawing()
  CreateSprite3D(No, No)
  Start3D()
    DisplaySprite3D(No, 0, 0)
  Stop3D()
EndProcedure

  InitSprite()
  InitSprite3D()
  InitKeyboard()
  ExamineDesktops()
  Dw = DesktopWidth(0)
  Dh = DesktopHeight(0)
  Dd = DesktopDepth(0)
  
  Wi = 32
  He = 32
  OpenScreen(Dw, Dh, Dd, "")
    CreateTileTest(1, Wi, He)
    For I = 0 To 15
      CreateTileMono(I + 2, Wi, He, I)
    Next I
    Global Dim Tile(255, 31)
    For I = 0 To 31
      For X = 0 To 255
        Tile(X, I) = 1
      Next
    Next
    For I = 0 To 15
      For X = 0 To 255
        Tile(X, 15 - I) = I + 2
      Next
    Next
    For X = 0 To 255
      For I = Int(10. + Cos(X / 8.) * 8.) To 15
        Tile(X, I) = 1
      Next
    Next

    Repeat
      Delay(1)
      Start3D()
        If OffsetTileX <= 0
          OffsetTileX = 0
          OffsetX = 0
        EndIf
        If OffsetTileX => ((255 - (Dw / 32) ) )
          OffsetTileX = ((255 - (Dw / 32) ) )
          OffsetX = 32 - 1
        EndIf
        For XS3 = 0 - 32 To Dw - 1 Step 32
          For YS3 = 0 To Dh - 1 Step 32
            ;Debug Str(XS3 / 32 + OffsetTileX) + "; " + Str(YS3 / 32)
            XX = XS3 / 32 + OffsetTileX
            If XX => 0
              Tile = Tile(XX, YS3 / 32)
              If Tile
                DisplaySprite3D(Tile, XS3 + OffsetX, YS3)
              EndIf
            EndIf
          Next
        Next
      Stop3D()
      FlipBuffers()
      ExamineKeyboard()
      If KeyboardPushed(#PB_Key_Right)
        If OffsetXAccel > -16
          OffsetXAccel - 2
        EndIf
      EndIf
      
      If KeyboardPushed(#PB_Key_Left)
        If OffsetXAccel < 16
          OffsetXAccel + 2
        EndIf
      EndIf
      OffsetX + OffsetXAccel
      If OffsetX > 31
        OffsetX - 32
        OffsetTileX - 1
      EndIf
      If OffsetX < 0
        OffsetX + 32
        OffsetTileX + 1
      EndIf
      If OffsetXAccel > 0
        OffsetXAccel - 1
      EndIf
      If OffsetXAccel < 0
        OffsetXAccel + 1
      EndIf
    Until KeyboardPushed(#PB_Key_Escape)
  CloseScreen()
  

[Michael Vogel]

Looks nice, I got remembered to 1980 when I saw the video game scramble and tried to implement that on my PET 2001...

[Demivec]

@Olliv: Here is a small adjustment needed for the example posted for large view screens. I present it merely to keep your example working and hopefully it is not considered an irritant.

It is presented in two parts to avoid posting all the intervening code

Code: Select all

Wi = 32
He = 32
OpenScreen(Dw, Dh, Dd, "")
;Add the following lines to test if screen is larger vertically than needed and set maxheight 'Dh2' appropriately
If Dh > ((He - 1) * 32)
  Dh2 = ((He - 1) * 32)
Else
  Dh2 = Dh
EndIf 

This portion modifies only the line at the start of the inner display loop with YS3 (changing 'Dh' to 'Dh2').

Code: Select all

For XS3 = 0 - 32 To Dw - 1 Step 32
      For YS3 = 0 To Dh2 - 1 Step 32 ; <== use maxheight based on screen and map size
        ;Debug Str(XS3 / 32 + OffsetTileX) + "; " + Str(YS3 / 32)
        XX = XS3 / 32 + OffsetTileX
        If XX => 0
          Tile = Tile(XX, YS3 / 32)
          If Tile
            DisplaySprite3D(Tile, XS3 + OffsetX, YS3)
          EndIf
        EndIf
      Next
    Next

The difference is shown in two thumbnails, the left one is before the change.

[Kaeru Gaman]

could a Moderator please cut the oldskool lessons off the discussing of the book?

I love oldskool and everything about tile-engines is my profession, but these are two topics, the original topic was the book.

[Demivec]

could a Moderator please cut the oldskool lessons off the discussing of the book?

I love oldskool and everything about tile-engines is my profession, but these are two topics, the original topic was the book.

I second the request.

[Olliv]

I understand nothing but I second the request too

We could create an other topic in the coding question section about the problems a coder meets when he want to create a scrolling game. For the 3 codes I publish, there are already in the forum.

[Rings]

splitted

[Olliv]

Thank you Rings!

[Olliv]

@Olliv: Here is a small adjustment needed for the example posted for large view screens. I present it merely to keep your example working and hopefully it is not considered an irritant.

It is presented in two parts to avoid posting all the intervening code

Code: Select all

Wi = 32
He = 32
OpenScreen(Dw, Dh, Dd, "")
;Add the following lines to test if screen is larger vertically than needed and set maxheight 'Dh2' appropriately
If Dh > ((He - 1) * 32)
  Dh2 = ((He - 1) * 32)
Else
  Dh2 = Dh
EndIf 

This portion modifies only the line at the start of the inner display loop with YS3 (changing 'Dh' to 'Dh2').

Code: Select all

For XS3 = 0 - 32 To Dw - 1 Step 32
      For YS3 = 0 To Dh2 - 1 Step 32 ; <== use maxheight based on screen and map size
        ;Debug Str(XS3 / 32 + OffsetTileX) + "; " + Str(YS3 / 32)
        XX = XS3 / 32 + OffsetTileX
        If XX => 0
          Tile = Tile(XX, YS3 / 32)
          If Tile
            DisplaySprite3D(Tile, XS3 + OffsetX, YS3)
          EndIf
        EndIf
      Next
    Next

The difference is shown in two thumbnails, the left one is before the change.

@Demivec

Well... Excuse me if come back again to you, but I understand nothing about your last observation.

I have two questions I hope you have time to answer:

1) What are the conditions of your last observation?
> Only for unidirectionnal scrolling (just vertical or just horizontal)? Or for multi-directionnal scrolling?

2) Is the left picture really what you see on your computer? Or is it a representative (symbolic) picture which announces a possible bug depending the specific dimensions on different computers?

Thank you.

Ollivier

[Demivec]

@Demivec

Well... Excuse me if come back again to you, but I understand nothing about your last observation.

I have two questions I hope you have time to answer:

1) What are the conditions of your last observation?
> Only for unidirectionnal scrolling (just vertical or just horizontal)? Or for multi-directionnal scrolling?

2) Is the left picture really what you see on your computer? Or is it a representative (symbolic) picture which announces a possible bug depending the specific dimensions on different computers?

1: It is for your horizontal scrolling example only. The simple fix I posted could be improved further by possibly centering the map vertically on the visible screen.
2: Yes. I have a larger screen view than you did and thus I see the map repeating (with an offset column) to fill the larger screen view. The same would happen if the map being used had been narrower than the screen.