SetGraphicsDriver GLMax2DDriver()
Graphics 640, 480, 0, NOSYNC


Global terrain:TImage[20, 15]


LoadTerrain("terrain.bmp")

While Not KeyHit(KEY_ESCAPE)

 DrawTerrain()
 DrawText ShowFPS(), 0, 0

 If MouseDown(1) Then
   EditTerrain(MouseX(), MouseY(), 20)
 End If

 Flip
 Cls

Wend



Function LoadTerrain(file:String)

 SetMaskColor 255, 0, 255
 Local img_terrain = LoadImage("terrain.bmp"), x, y, tmp_pixmap:TPixmap, tmp_terrain:TPixmap
 tmp_terrain = LockImage(img_terrain)

 For x = 0 To 19
  For y = 0 To 14
    terrain[x, y] = CreateImage(32, 32)

    tmp_pixmap = LockImage(terrain[Min(x, 19), Min(y, 14)])

    Local bx, by
    For bx = 0 To 31
     For by = 0 To 31
      WritePixel(tmp_pixmap, bx, by, ReadPixel(tmp_terrain, x*32+bx, y*32+by))
     Next
    Next

    UnlockImage(terrain[x, y])
  Next
 Next

 UnlockImage(img_terrain)
 img_terrain = Null

End Function


Function DrawTerrain()

 Local x, y

 For x = 0 To 19
  For y = 0 To 14
    DrawImage terrain[x, y], x*32, y*32
  Next
 Next

End Function


Function EditTerrain(x, y, r)

 Local x1, y1, p1

 x1 = 0
 y1  = -r
 p1  = y Shl 1+3

 While x1 <= -y1

   EditLine(x-x1, x+x1, y+y1)
   EditLine(x-x1, x+x1, y-y1)
   EditLine(x-y1, x+y1, y+x1)
   EditLine(x-y1, x+y1, y-x1)

   If p1 >= 0 Then
    y1 = y1 + 1
    p1 = p1 + ((x1 + y1) Shl (2+6))
   Else
    p1 = p1 + (x1 Shl (2+6))
   End If
   x1 = x1 + 1

 Wend

End Function


Function EditLine(x1, x2, y)

 Local x, tile:TImage, pixmap, locked:TImage, ux:Int, uy:Int

 If x2 < x1 Then
  Local s = x1
  x1 = x2
  x2 = s
 End If


 uy = y/32
 If y > -1 And uy < 15 Then

 For x = x1 To x2

   ux = x/32
   If x > -1 And ux < 20 Then

   locked = tile
   tile = terrain[ux, uy]
   If tile <> locked Then
    pixmap = LockImage(tile)
   End If

   WritePixel(pixmap, x Mod 32, y Mod 32, $FF000000)

   End If

 Next

 End If

End Function


Function ShowFps:Int()

 Global fps_show:Int
 Global fps_ms:Int = MilliSecs()
 Global fps_frames:Int


 fps_frames=fps_frames+1
 If MilliSecs()-fps_ms >= 1000 Then
  fps_show=fps_frames
  fps_frames=0
  fps_ms=MilliSecs()
 End If

 Return fps_show
   
End Function