Game state management The game state is managed through two primary structures and a maze array.
State structures Pacman state
Ghost state
Maze array
From src/include/misc.h:1-18 : struct pcman { float x, y; // Grid position (not pixels) float inc_x, inc_y; // Current direction (-1, 0, 1) float old_inc_x, old_inc_y; // Previous direction float old_x, old_y; // Previous position float yf, dir; // Calculation helpers int puntos; // Dots remaining int puntuacion; // Score int nivel; // Level 0-13 int tiempo; // Power-up duration int estado_pcman; // NORMAL or ENFADADO int num_vidas; // Lives remaining };
From src/include/misc.h:20-35 : struct fantasmas { float x [ 4 ], y [ 4 ]; // Position for each ghost float old_x [ 4 ], old_y [ 4 ]; // Previous positions float inc_x [ 4 ], inc_y [ 4 ]; // Movement increments float find_x [ 4 ], find_y [ 4 ]; // Current target float find_xp [ 4 ], find_yp [ 4 ]; // Predicted target (blue ghost) float old_mov_x [ 4 ], old_mov_y [ 4 ]; // Last movement int estado_fantasma [ 4 ]; // NORMAL, ENFADADO, or MUERTO int who; // Current ghost index (0-3) };
From src/misc.c:18-45 , the maze is a static 32x26 array: int c_array [MAXY_A * MAXX_A]; // Working copy int array [MAXY_A * MAXX_A] = { // 0 = wall // C (1) = circuit with dot // N (2) = nothing (walkable, no dot) // J (3) = walked path // P (4) = door (ghost house) // B (5) = power pellet };
Game states Defined in src/include/defines.h:3-5 :
#define NORMAL 0 // Normal gameplay #define ENFADADO 1 // Scared/edible (ghosts) or powered-up (Pacman) #define MUERTO 2 // Dead (ghosts returning to base)
Initialization The inicializa_structuras() function in src/misc.c:280-477 sets up game state.
Pacman initialization From misc.c:282-298 :
void inicializa_structuras ( struct pcman * pc , struct fantasmas * fan , int value ) { pc -> x = 7 ; pc -> y = 11 ; pc -> old_x = 7 ; pc -> old_y = 11 ; pc -> inc_x = 0 ; pc -> inc_y = - 1 ; // Start moving up pc -> old_inc_x = 0 ; pc -> old_inc_y = 0 ; pc -> estado_pcman = NORMAL; if (value == TRUE || value == COMENZAR) { pc -> puntos = NUM_PUNTOS; // 226 dots } if (value == COMENZAR) { pc -> nivel = 0 ; pc -> num_vidas = 2 ; pc -> puntuacion = 0 ; } }
Ghost initialization Each ghost starts at a different position in the “ghost house” (center of maze):
From misc.c:300-308 : fan -> who = 0 ; fan -> x [ fan -> who ] = 17 ; fan -> y [ fan -> who ] = 11 ; fan -> inc_x [ fan -> who ] = 1 ; // Moving right fan -> inc_y [ fan -> who ] = 0 ; fan -> old_mov_x [ fan -> who ] = 1 ; fan -> old_mov_y [ fan -> who ] = 0 ; fan -> find_x [ fan -> who ] = pc -> x; fan -> find_y [ fan -> who ] = pc -> y;
From misc.c:310-318 : fan -> who = 1 ; fan -> x [ fan -> who ] = 19 ; fan -> y [ fan -> who ] = 12 ; fan -> inc_x [ fan -> who ] = 0 ; fan -> inc_y [ fan -> who ] = 1 ; // Moving down // ... same pattern
Yellow ghost (index 2) and Gray ghost (index 3)
Similar initialization at positions (15, 11) and (16, 14) respectively.
Velocity initialization From misc.c:345-451 , velocity is set based on level:
switch ( pc -> nivel ) { case 0 : pc -> tiempo = 273 ; // Power-up duration (15 seconds * 18.2 Hz) inc_velocidad [ 0 ] = velocidades [ pc -> nivel ]; // 0.4 inc_velocidad [ 1 ] = velocidades [ pc -> nivel ]; inc_velocidad [ 2 ] = velocidades [ pc -> nivel ]; inc_velocidad [ 3 ] = velocidades [ pc -> nivel ]; break ; case 1 : pc -> tiempo = 198 ; // 11 seconds inc_velocidad [ 0 ] = velocidades [ 1 ]; // 0.4231 // ... }
Velocity array from misc.c:140-155 :
float velocidades [ 14 ] = { 0.4 , // Level 0 0.4231 , // Level 1 0.4462 , // Level 2 // ... increases up to 0.7 // Level 13 };
Ghost AI system The ghost AI is split between two files:
Target selection From src/misc.c:760-836 , each ghost has unique behavior:
Blue ghost (who=0)
Red ghost (who=1)
Yellow ghost (who=2)
Gray ghost (who=3)
Ambush behavior - Tries to predict Pacman’s positionFrom misc.c:760-780 : if (fan. estado_fantasma [ 0 ] == NORMAL) { if ( fan . x [ 0 ] == fan . find_xp [ 0 ] && fan . y [ 0 ] == fan . find_yp [ 0 ]) { fan . find_xp [ 0 ] = pc . x ; fan . find_yp [ 0 ] = pc . y ; fan . find_x [ 0 ] = fan . find_xp [ 0 ]; fan . find_y [ 0 ] = fan . find_yp [ 0 ]; } } else if (fan. estado_fantasma [ 0 ] == ENFADADO) { // Random target when scared alea [ 0 ] = rand () % MAXX_A; alea [ 1 ] = rand () % MAXY_A; fan . find_x [ 0 ] = alea [ 0 ]; fan . find_y [ 0 ] = alea [ 1 ]; } else { // Return to ghost house when dead fan . find_x [ 0 ] = 16 ; fan . find_y [ 0 ] = 12 ; }
Direct chase - Always targets Pacman’s current positionFrom misc.c:782-793 : if (fan. estado_fantasma [ 1 ] == NORMAL) { fan . find_x [ 1 ] = pc . x ; fan . find_y [ 1 ] = pc . y ; } else if (fan. estado_fantasma [ 1 ] == ENFADADO) { alea [ 0 ] = rand () % MAXX_A; alea [ 1 ] = rand () % MAXY_A; fan . find_x [ 1 ] = alea [ 0 ]; fan . find_y [ 1 ] = alea [ 1 ]; } else { fan . find_x [ 1 ] = 16 ; fan . find_y [ 1 ] = 12 ; }
Proximity-based - Chases only when within 9 cellsFrom misc.c:795-814 : if (fan. estado_fantasma [ 2 ] == NORMAL) { if ( fabs ( pc . x - fan . x [ 2 ]) < 9 && fabs ( pc . y - fan . y [ 2 ]) < 9 ) { fan . find_x [ 2 ] = pc . x ; fan . find_y [ 2 ] = pc . y ; } else { // Random patrol when far away fan . find_x [ 2 ] = rand () % MAXX_A; fan . find_y [ 2 ] = rand () % MAXY_A; } }
Patrol behavior - Chases within 12 cells, otherwise randomFrom misc.c:816-836 : if (fan. estado_fantasma [ 3 ] == NORMAL) { if ( fabs ( pc . x - fan . x [ 3 ]) < 12 && fabs ( pc . y - fan . y [ 3 ]) < 12 ) { fan . find_x [ 3 ] = pc . x ; fan . find_y [ 3 ] = pc . y ; } else { fan . find_x [ 3 ] = rand () % MAXX_A; fan . find_y [ 3 ] = rand () % MAXY_A; } }
Pathfinding algorithm The optener_movimientos_fantasmas() function in src/movefant.c:279-526 implements the core pathfinding.
Movement decision logic From movefant.c:282-356 , the algorithm considers:
Previous movement direction - Stored in fan->old_mov_x and fan->old_mov_yTarget position - From fan->find_x and fan->find_yWalkable cells - Checked via truex() and truey() helpers
Core logic for Y-axis movement (movefant.c:287-356):
if (fan -> old_mov_y [ fan -> who ] != 0 ) { if ( fan -> x [ fan -> who ] > fan -> find_x [ fan -> who ]) { if ( comprueba_distancias_x (fan)) { if ( truex ( - 1 , fan)) // Can move left? { fan -> inc_x [ fan -> who ] = - 1 ; fan -> inc_y [ fan -> who ] = 0 ; } } else devuelve_valores_aleatorios_y (fan); } else if ( fan -> x [ fan -> who ] < fan -> find_x [ fan -> who ]) { if ( comprueba_distancias_x (fan)) { if ( truex ( 1 , fan)) // Can move right? { fan -> inc_x [ fan -> who ] = 1 ; fan -> inc_y [ fan -> who ] = 0 ; } } else devuelve_valores_aleatorios_y (fan); } }
Wall collision helpers From movefant.c:29-41 :
int truex ( int value , struct fantasmas * fan ) { if (value == - 1 && c_array [( int )(( fan -> y [ fan -> who ] * 32 ) + ( fan -> x [ fan -> who ] + value))] == P) return 0 ; // Door blocks ghosts moving left else return ( c_array [( int )(( fan -> y [ fan -> who ] * 32 ) + ( fan -> x [ fan -> who ] + value))]); } int truey ( int value , struct fantasmas * fan ) { return ( c_array [( int )((( fan -> y [ fan -> who ] + value) * 32 ) + fan -> x [ fan -> who ])]); }
Returns non-zero if the cell is walkable (C, N, J, B, or P for ghosts moving right).
Randomization When ghosts hit a junction or dead end, devuelve_valores_aleatorios_x() and devuelve_valores_aleatorios_y() (movefant.c:121-277) add unpredictability:
void devuelve_valores_aleatorios_y ( struct fantasmas * fan ) { int alea_t ; fan -> inc_y [ fan -> who ] = 0 ; fan -> inc_x [ fan -> who ] = 0 ; if ( truex ( - 1 , fan) && truex ( 1 , fan) && truey ( fan -> old_mov_y [ fan -> who ], fan)) { alea_t = rand () % 30 ; if ( alea_t >= 0 && alea_t <= 9 ) fan -> inc_x [ fan -> who ] = 1 ; else if ( alea_t >= 10 && alea_t <= 19 ) fan -> inc_x [ fan -> who ] = - 1 ; else if ( alea_t >= 20 && alea_t <= 29 ) fan -> inc_y [ fan -> who ] = fan -> old_mov_y [ fan -> who ]; } // ... more cases }
This creates a 33% chance for each direction when multiple paths are available.
Collision detection From src/mov_fig.c:190-210 , collision uses distance-based detection:
if ( fabs ((xf + j [who]) - (old_xp + jp + 1 )) < 10 && fabs ((yf + i [who]) - (old_yp + ip)) < 10 ) { if ( fan -> estado_fantasma [who] == NORMAL) { // Pacman dies pc -> num_vidas -- ; if ( pc -> num_vidas < 0 ) menu_opciones ( FALSE ); inicializa_structuras (pc, fan, FALSE ); CntStep2 = 0 ; } else if ( fan -> estado_fantasma [who] == ENFADADO) { // Eat ghost switch (control_puntos_fan_muerto) { case 0 : writef (xf, yf, vaddr, " %2d " , 50 ); pc -> puntuacion += 50 ; break ; case 1 : writef (xf, yf, vaddr, " %3d " , 100 ); pc -> puntuacion += 100 ; break ; case 2 : writef (xf, yf, vaddr, " %3d " , 150 ); pc -> puntuacion += 150 ; break ; case 3 : writef (xf, yf, vaddr, " %3d " , 200 ); pc -> puntuacion += 200 ; break ; } fan -> estado_fantasma [who] = MUERTO; control_puntos_fan_muerto ++ ; } }
The collision radius is 10 pixels (roughly the size of the sprites). The control_puntos_fan_muerto variable tracks how many ghosts have been eaten in sequence for progressive scoring.
Scoring system Dot collection From misc.c:714-730 :
if (c_array [( int )( pc . x + ( pc . y * 32 ))] == C) { c_array [( int )( pc . x + ( pc . y * 32 ))] = J; // Mark as walked xp = COOR_X + ( pc . x * 8 ) - 6 ; yp = COOR_Y + ( pc . y * 8 ) - 8 ; putico (xp + 6 , yp + 4 , punto_negro, tablero -> pixels , 4 , 4 ); // Erase dot pc . puntos -- ; pc . puntuacion += 10 ; if ( pc . puntos == 0 ) { adelanta_nivel ( & fan, & pc); } }
10 points per dot.Power pellet From misc.c:663-675 :
if (c_array [( int )( pc . x + ( pc . y * 32 ))] == B) { c_array [( int )( pc . x + ( pc . y * 32 ))] = J; xp = COOR_X + ( pc . x * 8 ) - 6 ; yp = COOR_Y + ( pc . y * 8 ) - 9 ; putico (xp + 3 , yp + 2 , bak_asusta, tablero -> pixels , 10 , 10 ); pc . estado_pcman = ENFADADO; if ( fan . estado_fantasma [ 0 ] == NORMAL) fan . estado_fantasma [ 0 ] = ENFADADO; if ( fan . estado_fantasma [ 1 ] == NORMAL) fan . estado_fantasma [ 1 ] = ENFADADO; if ( fan . estado_fantasma [ 2 ] == NORMAL) fan . estado_fantasma [ 2 ] = ENFADADO; if ( fan . estado_fantasma [ 3 ] == NORMAL) fan . estado_fantasma [ 3 ] = ENFADADO; pc . puntuacion += 50 ; CntStep = 0 ; }
50 points per power pellet.Ghost consumption Progressive scoring for eating multiple ghosts in one power-up:
1st ghost: 50 points
2nd ghost: 100 points
3rd ghost: 150 points
4th ghost: 200 points
Level progression The adelanta_nivel() function in misc.c:485-489 handles level advancement:
void adelanta_nivel ( struct fantasmas * fan , struct pcman * pc ) { pc -> nivel ++ ; stargame (fan, pc, TRUE ); }
This is called when pc.puntos == 0 (all dots collected).
Level differences Ghost speed
Power-up duration
From misc.c:140-155 , ghost speed increases from 0.4 (level 0) to 0.7 (level 13+): float velocidades [ 14 ] = { 0.4 , 0.4231 , 0.4462 , 0.4692 , 0.4923 , 0.5154 , 0.5385 , 0.5615 , 0.5846 , 0.6077 , 0.6308 , 0.6538 , 0.6769 , 0.7 };
Pacman’s speed remains constant at 0.5 (misc.c:173). From misc.c:345-451 , power-up time decreases:
Level 0: 273 ticks (15 seconds)
Level 1: 198 ticks (11 seconds)
Level 2: 162 ticks (9 seconds)
Level 3: 126 ticks (7 seconds)
Level 4+: 90 ticks (5 seconds)
Level 13: 20 ticks (1 second)
Calculated as seconds * 18.2 (timer frequency). Maze reset From misc.c:491-503 :
void stargame ( struct fantasmas * fan , struct pcman * pc , int value ) { if (value == TRUE || value == COMENZAR) copyarray (); // Reset maze from original template inicializa_structuras (pc, fan, value); tablero = LoadImage ( "data/tablero.bmp" , 0 ); CntStep2 = 0 ; teclado (); }
The copyarray() function (misc.c:262-267) resets the working maze:
void copyarray ( void ) { int j; for (j = 0 ; j < MAXX_A * MAXY_A; j ++ ) c_array [j] = array [j]; }
Tunnel wrapping The maze has wraparound tunnels on the sides. From movefant.c:451-464 :
if (fan -> x [ fan -> who ] == 16 && fan -> y [ fan -> who ] == 1 ) { fan -> x [ fan -> who ] = 16 ; fan -> y [ fan -> who ] = 24 ; fan -> inc_y [ fan -> who ] = - 1 ; fan -> inc_x [ fan -> who ] = 0 ; } else if (fan -> x [ fan -> who ] == 16 && fan -> y [ fan -> who ] == 24 ) { fan -> x [ fan -> who ] = 16 ; fan -> y [ fan -> who ] = 1 ; fan -> inc_y [ fan -> who ] = 1 ; fan -> inc_x [ fan -> who ] = 0 ; }
Similar logic exists for Pacman in misc.c:651-660 .
Ghost house exit Ghosts leave the starting house at staggered intervals. From misc.c:840-893 :
if ( busca_posiciones [ 0 ] == TRUE ) { if ( fan . x [ 0 ] == 17 && fan . y [ 0 ] == 12 && fan . estado_fantasma [ 0 ] == NORMAL) { if (CntStep2 >= 50 && CntStep2 <= 100 ) { fan . find_x [ 0 ] = fan . find_xp [ 0 ] = pc . x ; fan . find_y [ 0 ] = fan . find_yp [ 0 ] = pc . y ; fan . inc_x [ 0 ] = 1 ; fan . inc_y [ 0 ] = 0 ; } else { fan . find_x [ 0 ] = 15 ; fan . find_y [ 0 ] = 12 ; } } }
Exit times:
Blue ghost: CntStep2 50-100
Red ghost: CntStep2 100-150
Yellow ghost: CntStep2 150-200
Gray ghost: CntStep2 200-240
This prevents all ghosts from exiting simultaneously at game start.