Tile-based game.....

#include <stdio.h>
#include <stdlib.h>
#include <SDL/SDL.h>

SDL_Surface *screen;
int game_state;
int i;
int x;
int y;
int bytecount;

SDL_Surface *tiles[3];
int world[100*100];//map is 100x100



//this is to be called from your game loop
//this is the same code from the earlier example
int player_x;//player's x position in the world
int player_y;//player's y position in the wolrd

//...insert code that get player input and updates player_x and player_y based on player input.

//assume player character is at center of screen
//find start position to draw from in tile array
int start_x;//assume tiles are 32x32 and screen width is 640. 
int start_y;//assume tiles are 32x32 and screen height is 480. 

void init_tile()
{
/*
     tiles[0] = SDL_LoadBMP("gfx/water.bmp");
     tiles[1] = SDL_LoadBMP("gfx/desert.bmp");
     tiles[2] = SDL_LoadBMP("gfx/grass.bmp");
*/

  	long size;
	int bytecount;
	int count;

  	
	FILE *f;
	f=fopen("maps/desert.map","r");
  	if (f==NULL) perror ("Error opening file desert.map");
  	else
  	{
    		fseek (f, 0, SEEK_END);
    		size=ftell (f);
		bytecount = size;  	
		fseek (f, 0, SEEK_SET);
	}
	
	int player_index = 0;//stores our position in the world array
	while(i<bytecount)
	{

		int temp = fgetc(f)-48;//read a tile index from the file
		world[player_index] = temp;//store value from file in our world map array
		//printf("%i", temp);
		printf(", %i", world[player_index]);
		++player_index;//move to next position in array
		i=i+1;
	}
	game_state=2;
}

void draw()
{
	int x, y;
	int tile_index;	
	SDL_Surface *curr_tile = tiles[tile_index];

	int draw_x = 0;//x position on screen to draw to
	int draw_y = 0;//y position on screen to draw to

	char *tilefile;//Tile to print
	
	start_x= player_x-10;
	start_y = player_y-7;
/* 
	SHORT DESCRIPTION: start_y/x = start position to draw from
	draw_x/y = Position on screen to draw to
	player_x/y = playersXpos
*/


	for(y = start_y; y < start_y+15; ++y)//again, assumes 15 rows
		{
			
          		for(x = start_x; x < start_x+20; ++x)//assumes 20 columns
          		{
               			tile_index = world[y*20+x]; //wich tile do we want to print? results in 0,1,2.
				//printf("world = %i", world[y*20+x]);//debugging

				//Printing the tiles got from tile_index
				if(tile_index==0)
				{
					tilefile="gfx/water.bmp";
				}
				if(tile_index==1)
				{
					tilefile="gfx/grass.bmp";
				}
				if(tile_index==2)
				{
					tilefile="gfx/desert.bmp";
				}

				if(tile_index!=-38)
				{
					ShowBMP(tilefile, screen, draw_x, draw_y);
				}
     				draw_x+=32;//move over 32 pixels because that is the width of one tile
     				
			}

     		draw_x=0;//When we have painted one row, reset X and put 32 to Y to start on the next row.
     		draw_y+=32;
     		}

}

void game_keypress()
{
	SDL_EnableUNICODE(1);
	SDL_Event event;
    	while( SDL_PollEvent( &event ) )
	{
        	switch( event.type )
		{
            	/* Look for a keypress */
            	case SDL_KEYDOWN:
                switch( event.key.keysym.sym )
			{
			case SDLK_RIGHT:
                        	player_x=player_x+32;
				break;
			case SDLK_LEFT:
				player_x=player_x-32;
				break;
			case SDLK_ESCAPE:
                        	fprintf(stderr, "\nQuiting game, have a nice day...\n");
				game_state = 4;
				break;
			default:
				break;
			}
		}
        }
}