declare sub LoadTiles()
declare sub LoadMap()
declare sub Init()
declare sub DrawScreen()

#define KeyLeft &h4B
#define KeyRight &h4D
#define KeyUp &h48
#define KeyDown &h50
#define KeyEsc &h01

type EngineType
    CameraX     as integer
    CameraY     as integer
    MaxCameraX  as integer
    MaxCameraY  as integer
    ScreenX     as integer
    ScreenY     as integer
    TileWidth   as integer
    TileHeight  as integer
    MapX        as integer
    MapY        as integer
end type

dim shared as any ptr Wall, Grass
dim shared Map(19, 19) as integer
dim shared Engine as EngineType

screen 14, 32

Init
LoadTiles
LoadMap
DrawScreen

do
    if multikey(KeyUp) then
        if Engine.CameraY > 0 then
            Engine.CameraY = Engine.CameraY - 1
            DrawScreen
        end if
    elseif multikey(KeyRight) then
        if Engine.CameraX < Engine.ScreenX then
            Engine.CameraX = Engine.CameraX + 1
            DrawScreen
        end if
    elseif multikey(KeyDown) then
        if Engine.CameraY < Engine.ScreenY then
            Engine.CameraY = Engine.CameraY + 1
            DrawScreen
        end if
    elseif multikey(KeyLeft) then
        if Engine.CameraX > 0 then
            Engine.CameraX = Engine.CameraX - 1
            DrawScreen
        end if
    elseif multikey(KeyEsc) then
        end
    endif
loop until inkey$ = "q"


'---------------------------------------------------------------------
'----SUBS-------------------------------------------------------------
'---------------------------------------------------------------------
sub DrawScreen()
    cls
    if Engine.CameraX < 0 then Engine.CameraX = 0
    if Engine.CameraY < 0 then Engine.CameraY = 0
    if Engine.CameraX > Engine.MaxCameraX then Engine.CameraX = Engine.MaxCameraX
    if Engine.CameraY > Engine.MaxCameraY then Engine.CameraY = Engine.MaxCameraY

    xTile = Engine.CameraX \ 32
    yTile = Engine.CameraY \ 32
    xOffset = Engine.CameraX mod 32
    yOffset = Engine.CameraY mod 32

    for x = 0 to Engine.ScreenX \ 32 + 1
        for y = 0 to Engine.ScreenY \ 32 + 1
            Tile = map (x + xTile, y + yTile)
            if Tile = 0 then
                put (x * 32 - xOffset, y * 32 - yOffset), Wall
            elseif Tile = 1 then
                put (x * 32 - xOffset, y * 32 - yOffset), Grass
            end if
        next y
    next x
    sleep 5
end sub


sub Init()
    screeninfo Engine.ScreenX, Engine.ScreenY
    Engine.TileWidth = 32
    Engine.TileHeight = 32
    Engine.MapX = 20
    Engine.MapY = 20
    Engine.MaxCameraX = Engine.TileWidth * Engine.MapX - Engine.ScreenX
    Engine.MaxCameraY = Engine.TileWidth * Engine.MapY - Engine.ScreenY
end sub

sub LoadTiles()
    Wall = imagecreate(32, 32)
    Grass = imagecreate(32, 32)
    bload "wall.bmp", Wall
    bload "grass.bmp", Grass
end sub

sub LoadMap()
    for y = 0 to 19
        for x = 0 to 19
            read Map(x, y)
        next x
    next y
end sub

data 1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0
data 0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1
data 1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0
data 0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1
data 1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0
data 0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1
data 1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0
data 0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1
data 1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0
data 0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1
data 1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0
data 0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1
data 1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0
data 0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1
data 1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0
data 0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1
data 1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0
data 0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1
data 1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0
data 0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1
data 1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0