Total newb working on a map building engine

;Draw map image and test world creation algorithm for tweaking

Global x=0
Global y=0

Global Grassmap
Global Oceanmap
Global Forestmap
Global Desertmap
Global Icemap

SeedRnd MilliSecs()

Global game = True

While game
	StartWorld ; initialize
	game = PlayGame() ; show the tiles
Wend

End

; ****************************


Function StartWorld()

	Graphics 800,600 ;Set video mode

	x=0 ;Reset coordinates to 0
	y=0

	SetBuffer BackBuffer() ;Draw these images to the backbuffer

	Grassmap=LoadImage("Grass 1.png") ;Load Images...
	Oceanmap=LoadImage("Ocean 2.png")
	Forestmap=LoadImage("Forest 1.png")
	Desertmap=LoadImage("Desert Sand 1.png")
	Icemap=LoadImage("Ice 1b.png")
	
End Function

Function PlayGame%()
	
	While y < 576
			
		Select Rand(0,4)
	
			Case 0 ;If Grass chosen, set DrawMapImage accordingly
			DrawMapImage=Grassmap ;and go to function to draw this image to

			;Repeat as needed...
			Case 1
			DrawMapImage=Oceanmap
			
			Case 2
			DrawMapImage=Forestmap
			
			Case 3
			DrawMapImage=Desertmap
			
			Case 4
			DrawMapImage=Icemap
			
		End Select

		DrawImage DrawMapImage,x,y
	
		x=x+64
		If x >= 768 Then
			y=y+64
			x=0
		EndIf
		
	Wend

	Text 20, 20, "Hit Enter for new terrain. Any other key returns to desktop."

	VWait
	Flip ; Put backbuffer image onto front screen and show image
	key = WaitKey()

	If KeyHit(28)
		Cls
		FreeImage Grassmap ;Free the following images from memory...
		FreeImage Oceanmap ;Repeat as needed...
		FreeImage Forestmap
		FreeImage Desertmap
		FreeImage Icemap
		Return True ; start over again. this is ugly code und should be changed
	Else
		Return False
	EndIf			

End Function

;Draw map image and test world creation algorithm for tweaking

Graphics 800,600
SetBuffer BackBuffer()

Global NoOfTiles = 4 ; set the number of tiles to 4, 5 including 0
Global TileWidth = 64 ; set the Tile height
Global TileHeight = 64 ; set the Tile width

; You have globals for each tiles. I have changed them and given them a number each.
; Now, these will describe each tile. They are not needed, but give you an idea of what number
; is related to a tile image. What i will do, is store each tile in a one dimensional array.
; Grassmap = 0
; Oceanmap = 1
; Forestmap = 2
; Desertmap = 3
; Icemap = 4

; Create an array to hold the tile images in
Dim tiles(NoOfTiles)
; Load the tiles into the array
LoadTiles()


; dim the map array. This is so you can fill it with tiles. It is set to 11 x 8 because that's how
; many tiles will fit into the current screen of 800 x 600. 

Global MapWidth = 11 ; this is actually 12, but because we're using 0, set to 11
Global MapHeight = 8 ; As above

Dim map(MapWidth,MapHeight)

; This function will fill the array with numbers, between 0 and 4. Each number represents a tile image
; 
GenerateMap()


SeedRnd MilliSecs()

Global game = True

While Not Keyhit(1) ; this will end the program by pressing ESCAPE key

	Cls

	If KeyHit(28) Then GenerateMap() ; if the enter key is pressed, the map is randomised again
	
	DrawTiles()
	Text 0,0, "Hit Enter for a new terrain"
		
	Flip ; Always try and flip at the end of the main loop. It's easier to debug if you only have one
	     ; Flip in the code
Wend

End

; ****************************


Function LoadTiles()


	Tiles(0) = LoadImage("Grass 1.png") ;Load Images...
	Tiles(1) = LoadImage("Ocean 2.png")
	Tiles(2) = LoadImage("Forest 1.png")
	Tiles(3) = LoadImage("Desert Sand 1.png")
	Tiles(4) = LoadImage("Ice 1b.png")
	
End Function

Function GenerateMap()

	; fill the array with random tiles. This will simply put a random number in each slot of the array
	; which will be used to select a tile from the TILES() array.
	For x = 0 To MapWidth
		For y = 0 To MapHeight
			map(x,y) = Rand(0,NoOfTiles) ; select random number
		Next
	Next
	
End Function

Function DrawTiles()

	; the drawimage command may look complicated, but if you split it up, what you have is:
	;DrawImage Tiles (  Map(x,y)) << Now, what your doing, is retrieving the tile number from the map
	;                                array, so blitz will take this number and this line will become:
	;DrawImage Tiles (  3 )  << So blitz will draw the 3rd image in the Tiles() array
	
	; 0 + (x * TileWidth) <<< basically, take the current x tile position, and multiply it by the tile
	;                         width to get the onscreen drawing X co-ord. The same applies for the Y
	;                         Co-ord.
	
	For x = 0 To MapWidth
		For y = 0 To MapHeight
			DrawImage Tiles(Map(x,y)), 0 + (x * TileWidth), 0 + (y * TileHeight)
		Next
	Next
	
End Function