Question

using a file I want to create a map and I am wondering about the best approach doing so.
Actually I searched the forum but I only found map generation algorithms that randomly creates maps.

Let’s look at a minimal example.
e.g. Ihave a file containing

0110
1001
1000
0000

Every 0 shall be water and every 1 shall be earth.
I would handle this by simply havin two different bitmaps and loading them at the right coordinates. That’d be simple.

But let’s guess we have a 1000*1000 big map and there is only enough space for 16*16 tiles per frame. Then I’d get the current position and would build the map around it.

Assuming we can only display 3*3 tiles, using the minimal example and being at position (2,2) where x and y is element 1..4 so what the user could see at this time would be:

011
100
100

Solution

I thought about using a text file, where a line represents the x-coordinate direction and
a column represents the y-coordinate direction. The whole file is being loaded at the beginning of the program. This shouldn’t use too much ram assuming 1 tile needs 1 byte, what should be enough.

For redrawing the map when the user is moving, I’d get the moving direction and slide the current Bitmap for the height/width of a tile in the opposite direction and only look up the bitmaps for the new blank spaces. So I only need to look up the tile information for m+n-1 (where m is the amount of displayed tiles in y and n in x direction) tiles (max case if moving diagonal) instead of loading m*n tiles everytime the user moves.

Example

I created an example to make the above given example more easily to understand.
this is the whole map:

We can only display 3*3 tiles and the user is at position (2,2) so what we’d actually see is:

now he is moving towards the bottom right corner:

and the black framed section is being move to the opposite direction, so that we get:

now the blank tiles (black framed white areas) have to be looked up and teh final result will be:

Question

is this a good way of building a map? Or are there much faster functions, maybe already implemented in the microsoft xna-gamestudio package ?

Answer 1

I would pre-fetch 1-2 tiles range outside the screen view, so that you won’t have weird pop-up as the player move.

But if your game is a top-down tile game, this solution is quite conservative. In most hardware today, you could create a very big range around the player without problem. Just look at the number of block Minecraft can process and display. Since you are reusing the same texture, you just load the asset once and reuse them in a tile, which would probably an object with very little memory footprint.

Have you tried implementing it yet?