I would like my character to be the center of the screen at all times. I am using allegro and C++. Right now I am rendering the full 30x30 map at all times. But my end goal is to have only 9x9 rendering at once. I don't know if I should do this by changing the displays variables. (tried this but it just changed the windows size.) Or change the which part of the map is displayed. ( I tried this but the character wasnt centered and the map did change but character moved left, and the map followed. So I stayed in the same spot indefinitely. )

I achieved this result with this code.

            for(int col=0;col<height;col++) {                 for(int row=0;row<width;row++) {                     al_draw_bitmap_region(tileset, mv[col][row].sx * 16, mv[col][row].sy * 16, 16, 16, (row*16 + hero.wloc*16), col*16, 0);                 }             }  
 

And it looks like this (Before and after 7 movements. Notice how the character isnt centered and the map isnt being drawn around him.)

Here is something I am curious about. Should I draw the whole map or only the part I am currently on?

            for(int col=0;col<height;col++) {                 for(int row=0;row<width;row++) {                     al_draw_bitmap_region(tileset, mv[col][row].sx * 16, mv[col][row].sy * 16, 16, 16, row*16, col*16, 0);                 }             }  

For reference here is a screenshot of my character. Notice how he is in the bottom right corner.

Okay. I deleted the previous attempt at centering and this is how my character is displayed. Every time he moves the screen stays stationary. (notice how he is at bottom right of screen instead of centered.)

The following video is an example of how I want my character to behave.

A release of my game.

https://www.dropbox.com/s/pxnnfmvwgslkxcs/negfaron.rar

Source code

main.cpp - http://pastie.org/5565697

make_map.h - http://pastie.org/5565698

main.h - http://pastie.org/5565699

Display initialization

ALLEGRO_DISPLAY* display = NULL;

Draw only the onscreen tiles and a 1 tile margin around the screen edges to make smooth scrolling easier. In other words, if your display is 15x15 tiles then draw 17x17 tiles.

As for centering the map around the character;

Start by getting your map x/y (which tile are you on) to use as the point to center on.

Subtract half the screen width (in tiles) from x and half the height from y.

This should give you the x/y of the tile to be placed in the upper-left corner.

I haven't looked at your code but I think you could probably take it from there.

If you want to the screen to not scroll its edges past the map edge then you'll need to do some bounds checking. For instance, run the above calculations and if x or y is negative then set them to 0. If they're greater than the map dims minus the screen dims then set them to map dims minus screen dims, etc.

Okay, I will try to always render the hero at the center of the map first. brb.

Edit: Alright the game is centered properly. Thank you for the answer.