RogueLulz, Part I: Drawing the Map, Walking Around, Basic Monsters and Attacking. By Joe Sixpack in Technology Fri Nov 30, 2007 at 10:52:27 AM EST Tags: RogueLulz, roguelike, computer games, the RORing 80's (all tags)
	The first of a multi-part series on how to write an 80's style roguelike. You should be familiar with c to better understand the source code. A C99 compiler (I use gcc) and a curses compatible library (I use ncurses) is required for compiling the code snippets in the article. The easiest way get both running on windows is to install cygwin.

1.1. Drawing the Map The first thing we need is a map (aka level) to walk around in. To keep things simple we'll use a hard coded map for now (generating random maps will be discussed in a later RogueLulz article): ############### #      #      # #             # #      ### #### #### ###   #  # #          #  # #          #  # #             # #          #  # ############### # - wall Keeping with the tradition established by Rogue, we will use the at-mark (@) as our protagonist. The following code initializes a curses screen, draws the map and the player character and exits after a key has been pressed: #include <curses.h> char *map[]={     "###############",     "#      #      #",     "#             #",     "#      ### ####",     "#### ###   #  #",     "#          #  #",     "#          #  #",     "#             #",     "#          #  #",     "###############" }; int main() {     //initialize curses     keypad(initscr(),1);     curs_set(0);         //player's starting coordinates     int y=1;     int x=1;         //draw map     for (int yy=0;yy<10;yy++)         for (int xx=0;xx<15;xx++)             mvaddch(yy,xx,map[yy][xx]);     //draw player     mvaddch(y,x,'@');     //wait for key press before leaving     getch();     //clean up after we've finished using curses     return endwin(); } You can compile the code by running gcc 1.1.c -std=c99 -lcurses -o roguelulz 1.2. Walking Around Now that we have our map, let's handle input from the user: the arrow keys will move @ and the escape key will quit the game. We'll also put the drawing (mvaddch) and keyboard input (getch) in a while loop so that the program doesn't exit after one key press: #define ESC 27 //ASCII for escape //last key pressed int c=0; do {     //draw map     for (int yy=0;yy<10;yy++)         for (int xx=0;xx<15;xx++)             mvaddch(yy,xx,map[yy][xx]);             //move player if there is no wall on the way     if (KEY_UP==c && ' '==map[y-1][x])         y--;     if (KEY_DOWN==c && ' '==map[y+1][x])         y++;     if (KEY_LEFT==c && ' '==map[y][x-1])         x--;     if (KEY_RIGHT==c && ' '==map[y][x+1])         x++;             //draw player     mvaddch(y,x,'@'); //quit when ESC is pressed } while((ESC!=(c=getch()))); Compile again: gcc 1.2.c -std=c99 -lcurses -o roguelulz And @ can now walk around the map! 1.3. Basic Monsters It's time to add some monsters - for now they'll just hang around waiting to be slain, we'll leave the AI for later. First let's define a struct to represent a monster. Every monster should have a location on the map and hitpoints- as should the player. The ent structure (short for entity) will be able to represent both: typedef struct {     int y,x,hp; }ent; We'll have a list of 12 entities in our map- 1 for the player and 11 monsters for him to fight: #define ENTS_ 12 ent ent_l[ENTS_]; We'll also add a two dimensional array ent_m the size of our map, such that if an entity in our ent_l list is located on tile (x,y) in the map, ent_m[y][x] will point to it (Otherwise it will be NULL): #define Y_ 10 #define X_ 15 ent *ent_m[Y_][X_]; Previous references to our map's dimensions have also been replaced by Y_ & X_ so we could easily change its size later. The ent_m array would allow us to easily find out if a tile is occupied in the following function. We initialise each of our entities to have 3 hitpoints and start in a random vacant tile (one that contains no wall and no other entity): void init_ent() {     for (int e=0;e<ENTS_;e++) {         ent *ce=&ent_l[e];         ce->hp=3;         do {             ce->y=rand()%Y_;             ce->x=rand()%X_;         } while ( '#'==map[ce->y][ce->x] || NULL!=ent_m[ce->y][ce->x] );         ent_m[ce->y][ce->x]=ce;     } } At this point we can change the x & y variables inside the main() function to pointers to the first entity, which is none other than our hero, @: //initialize entities srand(time(0)); init_ent();     //player's starting coordinates int *y=&ent_l[0].y; int *x=&ent_l[0].x; Now @ starts at a pseudo-random position every time we load the game. Let's also change the line responsible for drawing the player to also draw the monsters: //draw entities for(int e=0;e<ENTS_;e++){     mvaddch(ent_l[e].y,ent_l[e].x, 0==e?'@':'m'); } Compile and check out the changes: gcc 1.3.c -std=c99 -lcurses -o roguelulz 1.4. Attacking As you may have noticed, although the monsters are placed and drawn, @ still passes through them as if they aren't. In this final section of RogueLulz, Part I we will implement a simple attack. Every time @ walks into a monster, the monster's hitpoints will be reduced by 1. When a monster reaches 0 hitpoints it dies. First we modify the drawing code to only draw entities with more than 0 hitpoints: //draw entities for(int e=0;e<ENTS_;e++){     if (ent_l[e].hp>0)         mvaddch(ent_l[e].y,ent_l[e].x, 0==e?'@':'m'); Then, we modify the movement code to have @ attack monsters he walks into, instead of just walking through them: //move player if there is no living entity on the way void move_to(int *y,int *x,int dy,int dx) {     //remove reference to the player's old position     ent_m[*y][*x]=NULL;         //if the destination tile has an entity in it     if (NULL!=ent_m[*y+dy][*x+dx]) {         //decrement hitpoints of the entity at the destination tile         ent *de=ent_m[*y+dy][*x+dx];         de->hp--;         //if it's still alive don't move into its place         if (0 < de->hp) {             dy=0;             dx=0;         //if it's dead remove its reference         } else {             ent_m[*y+dy][*x+dx]=NULL;         }     }     //update player's position     *y+=dy;     *x+=dx;     //add reference to the player's new position     ent_m[*y][*x]=&ent_l[0]; } and in the main loop: //move player if there is no wall on the way if (KEY_UP==c && ' '==map[*y-1][*x])     move_to(y,x,-1,0); if (KEY_DOWN==c && ' '==map[*y+1][*x])     move_to(y,x,1,0); if (KEY_LEFT==c && ' '==map[*y][*x-1])     move_to(y,x,0,-1); if (KEY_RIGHT==c && ' '==map[*y][*x+1])     move_to(y,x,0,1); At last, compile RogueLulz, Part I's final result: gcc 1.4.c -std=c99 -lcurses -o roguelulz 1.5. Conclusion and Future Installments Thus far we have learned how to draw the map, walk around it, add some dumb monsters and even attack them. In the next installments we'll add random map generation, multilevel dungeons, field-of-view/line-of-sight, AI and winning/losing conditions. 1.6. The Final Source Code #include <curses.h> #include <stdlib.h> #include <time.h> #define ESC 27// ASCII for escape typedef struct {     int y,x,hp; }ent; #define ENTS_ 12 ent ent_l[ENTS_]; #define Y_ 10 #define X_ 15 ent *ent_m[Y_][X_]; char *map[]={     "###############",     "#      #      #",     "#             #",     "#      ### ####",     "#### ###   #  #",     "#          #  #",     "#          #  #",     "#             #",     "#          #  #",     "###############" }; void init_ent() {     for (int e=0;e<ENTS_;e++) {         ent *ce=&ent_l[e];         ce->hp=3;         do {             ce->y=rand()%Y_;             ce->x=rand()%X_;         } while ( '#'==map[ce->y][ce->x] || NULL!=ent_m[ce->y][ce->x] );         ent_m[ce->y][ce->x]=ce;     } } //move player if there is no living entity on the way void move_to(int *y,int *x,int dy,int dx) {     //remove reference to the player's old position     ent_m[*y][*x]=NULL;         //if the destination tile has an entity in it     if (NULL!=ent_m[*y+dy][*x+dx]) {         //decrement hitpoints of the entity at the destination tile         ent *de=ent_m[*y+dy][*x+dx];         de->hp--;         //if it's still alive don't move into its place         if (0 < de->hp) {             dy=0;             dx=0;         //if it's dead remove its reference         } else {             ent_m[*y+dy][*x+dx]=NULL;         }     }     //update player's position     *y+=dy;     *x+=dx;     //add reference to the player's new position     ent_m[*y][*x]=&ent_l[0]; } int main() {     //initialize curses     keypad(initscr(),1);     curs_set(0);     //initialize entities     srand(time(0));     init_ent();     //player's starting coordinates     int *y=&ent_l[0].y;     int *x=&ent_l[0].x;     //last key pressed     int c=0;     do {         //draw map         for (int yy=0;yy<Y_;yy++)             for (int xx=0;xx<X_;xx++)                 mvaddch(yy,xx,map[yy][xx]);         //move player if there is no wall on the way         if (KEY_UP==c && ' '==map[*y-1][*x])             move_to(y,x,-1,0);         if (KEY_DOWN==c && ' '==map[*y+1][*x])             move_to(y,x,1,0);         if (KEY_LEFT==c && ' '==map[*y][*x-1])             move_to(y,x,0,-1);         if (KEY_RIGHT==c && ' '==map[*y][*x+1])             move_to(y,x,0,1);         //draw entities         for (int e=0;e<ENTS_;e++) {             if (ent_l[e].hp>0)                 mvaddch(ent_l[e].y,ent_l[e].x, 0==e?'@':'m');         }     //quit when ESC is pressed     } while ((ESC!=(c=getch())));     //clean up after we've finished using curses     endwin(); } 1.7. Further Reading The rec.games.roguelike.development newsgroup, browseable through Google Groups. The Roguelike Dev FAQ. RogueBasin, a wiki devoted to roguelikes.

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Google roguelike curses cygwin Rogue 1.1.c mvaddch getch 1.2.c struct srand 1.3.c 1.4.c Google Groups Roguelike Dev FAQ RogueBasin Also by Joe Sixpack