game.c

   1
   2 /**
   3  *
   4  * Tennix! SDL Port
   5  * Copyright (C) 2003, 2007 Thomas Perl <thp@perli.net>
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License
   9  * as published by the Free Software Foundation; either version 2
  10  * of the License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  20  * MA  02110-1301, USA.
  21  *
  22  **/
  23
  24 #include <stdio.h>
  25 #include <math.h>
  26
  27 #include "tennix.h"
  28 #include "game.h"
  29 #include "graphics.h"
  30 #include "input.h"
  31 #include "sound.h"
  32
  33 void game( bool singleplayer) {
  34     GameState s = {
  35         { 0, 0, 0.0, 0.0, 0.0 },
  36         { 0, 0, 0, 0, 0 },
  37         { GAME_X_MIN-RACKET_X_MID*2, GAME_Y_MID, 0, 0, 1, DESIRE_NORMAL, PLAYER_TYPE_HUMAN, false, 0, 0, PLAYER_ACCEL_DEFAULT },
  38         { GAME_X_MAX+RACKET_X_MID*2, GAME_Y_MID, 0, 0, 0, DESIRE_NORMAL, PLAYER_TYPE_HUMAN, false, 0, 0, PLAYER_ACCEL_DEFAULT },
  39         0,
  40         0,
  41         0,
  42         true,
  43         "welcome to tennix " VERSION,
  44         { 0 },
  45         { 0 },
  46         REFEREE_NORMAL,
  47         0,
  48         WINNER_NONE,
  49         false,
  50         GR_CTT_GRASS,
  51         -1,
  52         { 0 },
  53         0,
  54         false,
  55         { { { 0 } } },
  56         0.0,
  57         SOUND_MAX,
  58         0.0,
  59         0.0,
  60         0
  61     };
  62
  63     strcpy( s.game_score_str, format_game( &s));
  64     strcpy( s.sets_score_str, format_sets( &s));
  65
  66     Uint32 ot = SDL_GetTicks();
  67     Uint32 nt;
  68     Uint32 dt = GAME_TICKS;
  69     Uint32 diff;
  70     Uint32 accumulator = 0;
  71     bool quit = false;
  72     int x, y, z;
  73
  74 #ifdef ENABLE_FPS_LIMIT
  75     Uint32 ft, frames; /* frame timer and frames */
  76 #endif
  77
  78     if( singleplayer) {
  79 #ifdef DEBUG
  80         s.player1.type = PLAYER_TYPE_AI;
  81 #endif
  82         s.player2.type = PLAYER_TYPE_AI;
  83     }
  84
  85     game_setup_serve( &s);
  86
  87     /* smoothen n-gram */
  88     for( x = 0; x<NGRAM_STEPS; x++) {
  89         for( y = 0; y<NGRAM_STEPS; y++) {
  90             for( z = 0; z<NGRAM_STEPS; z++) {
  91                 s.ngram[x][y][z] = 1;
  92             }
  93         }
  94     }
  95
  96 #ifdef ENABLE_FPS_LIMIT
  97     frames = 0;
  98     ft = SDL_GetTicks();
  99 #endif
 100     while( !quit) {
 101         nt = SDL_GetTicks();
 102         diff = nt-ot;
 103         if( diff > 2000) {
 104             diff = 0;
 105         }
 106
 107         accumulator += diff;
 108         ot = nt;
 109
 110         while( accumulator >= dt) {
 111             quit = step( &s);
 112             s.time += dt;
 113             accumulator -= dt;
 114
 115             if( s.was_stopped) {
 116                 ot = SDL_GetTicks();
 117                 s.was_stopped = false;
 118             }
 119         }
 120
 121 #ifdef ENABLE_FPS_LIMIT
 122         while (frames*1000.0/((float)(SDL_GetTicks()-ft+1))>(float)(DEFAULT_FPS)) {
 123             SDL_Delay(10);
 124         }
 125         frames++;
 126 #endif
 127
 128         render( &s);
 129     }
 130
 131 }
 132
 133 bool step( GameState* s) {
 134     Uint8 *keys;
 135     SDL_Event e;
 136
 137     if( get_phase( s) < 1.0) {
 138         if( !s->ground.jump) {
 139             s->play_sound = SOUND_GROUND;
 140
 141             if( IS_OUT_Y( s->ball.y)) {
 142                 /* out - responsibilities stay the same */
 143                 s->status = "out!";
 144                 s->play_sound = SOUND_OUT;
 145                 s->referee = REFEREE_OUT;
 146             } else {
 147                 /* not out - responsibilities change */
 148                 s->player1.responsible = !(s->player2.responsible = !s->player2.responsible);
 149                 s->status = format_status( s);
 150                 s->referee = REFEREE_NORMAL;
 151             }
 152         }
 153         s->ground.jump = 3;
 154         s->ground.x = s->ball.x;
 155         s->ground.y = s->ball.y;
 156     } else {
 157         if( s->ground.jump && !(s->time%5)) s->ground.jump--;
 158     }
 159
 160     if( IS_OUT_X(s->ball.x) || IS_OFFSCREEN_Y(s->ball.y)) {
 161         if( IS_OFFSCREEN( s->ball.x, s->ball.y)) {
 162             s->player1_serves = s->player1.responsible;
 163
 164             score_game( s, s->player2.responsible);
 165             strcpy( s->game_score_str, format_game( s));
 166             strcpy( s->sets_score_str, format_sets( s));
 167
 168             if( s->player1.responsible) {
 169                 if( s->player1.type == PLAYER_TYPE_HUMAN && s->player2.type == PLAYER_TYPE_AI) {
 170                     s->status = "computer scores";
 171                 } else {
 172                     s->status = "player 2 scores";
 173                 }
 174                 s->referee = REFEREE_PLAYER2;
 175             } else {
 176                 if( s->player1.type == PLAYER_TYPE_HUMAN && s->player2.type == PLAYER_TYPE_AI) {
 177                     s->status = "player scores";
 178                 } else {
 179                     s->status = "player 1 scores";
 180                 }
 181                 s->referee = REFEREE_PLAYER1;
 182             }
 183
 184             game_setup_serve( s);
 185             s->play_sound = SOUND_APPLAUSE;
 186             SDL_Delay( 500);
 187             start_fade();
 188             s->was_stopped = true;
 189             s->history_size = 0;
 190             s->history_is_locked = 0;
 191             s->ngram_prediction = 0.0;
 192 #ifdef DEBUG
 193             printf( "-- game reset --\n");
 194 #endif
 195         }
 196
 197         if( IS_OUT_X(s->ball.x)) {
 198             if( !s->history_is_locked && s->referee != REFEREE_OUT) {
 199                 s->history[s->history_size] = (int)(NGRAM_STEPS*s->ball.y/HEIGHT);
 200                 s->history_size++;
 201                 if( s->history_size == 3) {
 202                     s->ngram[s->history[0]][s->history[1]][s->history[2]] += 10;
 203 #ifdef DEBUG
 204                     printf( "history: %d, %d, %d\n", s->history[0], s->history[1], s->history[2]);
 205 #endif
 206                     s->ngram_prediction = ngram_predictor( s);
 207                     s->history[0] = s->history[1];
 208                     s->history[1] = s->history[2];
 209                     s->history_size--;
 210                 }
 211                 s->history_is_locked = true;
 212             }
 213             if( s->ball.move_x <= 0 && IS_NEAR_X( s->player1.x, s->ball.x) && IS_NEAR_Y( s->player1.y, s->ball.y) && s->player1.state && s->referee != REFEREE_OUT) {
 214                 s->ball.x = GAME_X_MIN;
 215                 if( s->player1.state == PLAYER_STATE_MAX) {
 216                     s->ball.move_x = PLAYER_POWERSHOT;
 217                 } else {
 218                     s->ball.move_x = 2.5 + 2.0*s->player1.state/PLAYER_STATE_MAX;
 219                 }
 220                 s->ball.move_y = get_move_y( s, 1);
 221                 s->player2.responsible = !(s->player1.responsible = 1);
 222                 s->ball.jump += 1.0-2.0*(s->player1.state<5);
 223                 s->play_sound = SOUND_RACKET;
 224                 pan_sample(SOUND_RACKET, 0.4);
 225             } else if( s->ball.move_x >= 0 && IS_NEAR_X( s->player2.x, s->ball.x) && IS_NEAR_Y( s->player2.y, s->ball.y) && s->player2.state && s->referee != REFEREE_OUT) {
 226                 s->ball.x = GAME_X_MAX;
 227                 if( s->player2.state == PLAYER_STATE_MAX) {
 228                     s->ball.move_x = -PLAYER_POWERSHOT;
 229                 } else {
 230                     s->ball.move_x = -(2.5 + 2.0*s->player2.state/PLAYER_STATE_MAX);
 231                 }
 232                 s->ball.move_y = get_move_y( s, 2);
 233                 s->player1.responsible = !(s->player2.responsible = 1);
 234                 s->ball.jump += 1.0-2.0*(s->player2.state<5);
 235                 s->play_sound = SOUND_RACKET;
 236                 pan_sample(SOUND_RACKET, 0.6);
 237             }
 238         }
 239     } else {
 240         s->history_is_locked = false;
 241     }
 242
 243     /* Update ball_dest for debugging purposes */
 244     get_move_y( s, 1);
 245     get_move_y( s, 2);
 246
 247     s->ball.x += s->ball.move_x;
 248     s->ball.y += s->ball.move_y;
 249
 250     if( s->player1.state) s->player1.state--;
 251     if( s->player2.state) s->player2.state--;
 252
 253     SDL_PollEvent( &e);
 254     keys = SDL_GetKeyState( NULL);
 255     switch(e.type) {
 256         case SDL_JOYAXISMOTION:
 257             if (e.jaxis.axis == JOYSTICK_Y_AXIS) {
 258                 s->joystick_y = JOYSTICK_PERCENTIZE(e.jaxis.value);
 259             } else if (e.jaxis.axis == JOYSTICK_X_AXIS) {
 260                 s->joystick_x = JOYSTICK_PERCENTIZE(e.jaxis.value);
 261             }
 262             break;
 263         case SDL_JOYBUTTONUP: case SDL_JOYBUTTONDOWN:
 264             if (e.jbutton.button == JOYSTICK_BUTTON_A) {
 265                 s->joystick_a = (e.jbutton.state == SDL_PRESSED);
 266             }
 267             break;
 268     }
 269
 270     if( keys['c'] && s->time%50==0) {
 271         s->court_type++;
 272         if( s->court_type > GR_CTT_LAST) {
 273             s->court_type = GR_CTT_FIRST;
 274         }
 275     }
 276
 277     if( !is_fading() && !s->is_over) {
 278         if( s->player1.type == PLAYER_TYPE_HUMAN) {
 279            input_human( &s->player1,
 280                    keys['w'] || keys[SDLK_UP] || s->joystick_y < -JOYSTICK_TRESHOLD,
 281                    keys['s'] || keys[SDLK_DOWN] || s->joystick_y > JOYSTICK_TRESHOLD,
 282                    keys['d'] || keys[SDLK_SPACE] || keys[SDLK_LCTRL] || s->joystick_a,
 283                    ENABLE_MOUSE,
 284                    s);
 285         } else {
 286             input_ai( &s->player1, &s->ball, &s->player2, s);
 287         }
 288
 289         if( s->player2.type == PLAYER_TYPE_HUMAN) {
 290             input_human( &s->player2, keys['o'], keys['l'], keys['k'], false, s);
 291         } else {
 292             input_ai( &s->player2, &s->ball, &s->player1, s);
 293         }
 294     }
 295
 296     if( keys['f']) SDL_WM_ToggleFullScreen( screen);
 297     if( keys['y']) SDL_SaveBMP( screen, "screenshot.bmp");
 298
 299     if( keys['p']) {
 300         while( keys['p']) {
 301             SDL_PollEvent( &e);
 302             keys = SDL_GetKeyState( NULL);
 303             SDL_Delay( 10);
 304         }
 305         while( keys['p'] == 0) {
 306             SDL_PollEvent( &e);
 307             keys = SDL_GetKeyState( NULL);
 308             SDL_Delay( 10);
 309         }
 310         while( keys['p']) {
 311             SDL_PollEvent( &e);
 312             keys = SDL_GetKeyState( NULL);
 313             SDL_Delay( 10);
 314         }
 315         s->was_stopped = true;
 316     }
 317
 318     if( keys[SDLK_ESCAPE] || keys['q']) return true;
 319
 320     limit_value( &s->player1.y, PLAYER_Y_MIN, PLAYER_Y_MAX);
 321     limit_value( &s->player2.y, PLAYER_Y_MIN, PLAYER_Y_MAX);
 322     limit_value( &s->ball.jump, BALL_JUMP_MIN, BALL_JUMP_MAX);
 323
 324     return false;
 325 }
 326
 327 void render( GameState* s) {
 328     if (s->play_sound != SOUND_MAX) {
 329         play_sample(s->play_sound);
 330         s->play_sound = SOUND_MAX;
 331     }
 332     if( s->winner != WINNER_NONE) {
 333         if( !s->is_over) {
 334             start_fade();
 335             s->is_over = true;
 336         }
 337         clear_screen();
 338         store_screen();
 339         show_sprite( GR_RACKET, 2*(s->winner-1), 4, WIDTH/2 - get_image_width( GR_RACKET)/8, HEIGHT/2 - get_image_height( GR_RACKET), 255);
 340         sprintf( s->game_score_str, "player %d wins the match with %s", s->winner, format_sets( s));
 341         font_draw_string( GR_DKC2_FONT, s->game_score_str, (WIDTH-font_get_string_width( GR_DKC2_FONT, s->game_score_str))/2, HEIGHT/2 + 30, s->time/20, ANIMATION_WAVE | ANIMATION_BUNGEE);
 342         updatescr();
 343         return;
 344     }
 345     if (s->old_court_type != s->court_type) {
 346         clear_screen();
 347         fill_image(s->court_type, 120, 120, 400, 250);
 348         show_image(GR_COURT, 0, 0, 255);
 349         s->old_court_type = s->court_type;
 350         store_screen();
 351     }
 352     show_sprite( GR_REFEREE, s->referee, 4, 250, 10, 255);
 353     show_image( GR_SHADOW, s->ball.x-BALL_X_MID, s->ball.y + get_phase( s) - BALL_Y_MID, 255);
 354
 355     show_sprite( GR_RACKET, (!s->player1.state), 4, s->player1.x-RACKET_X_MID, s->player1.y-RACKET_Y_MID, 255);
 356     show_sprite( GR_RACKET, (!s->player2.state)+2, 4, s->player2.x-RACKET_X_MID, s->player2.y-RACKET_Y_MID, 255);
 357
 358     if( s->ground.jump) {
 359         show_sprite( GR_GROUND, s->ground.jump-1, 3, s->ground.x - BALL_X_MID, s->ground.y - BALL_Y_MID, 128);
 360     }
 361
 362     if( s->ball.move_x > 0) {
 363         show_sprite( GR_BALL, (s->time/500)%4, 4, s->ball.x-BALL_X_MID, s->ball.y-BALL_Y_MID, 255);
 364     } else if( s->ball.move_x < 0) {
 365         show_sprite( GR_BALL, 3-(s->time/500)%4, 4, s->ball.x-BALL_X_MID, s->ball.y-BALL_Y_MID, 255);
 366     } else {
 367         show_sprite( GR_BALL, 0, 4, s->ball.x-BALL_X_MID, s->ball.y-BALL_Y_MID, 255);
 368     }
 369
 370
 371     font_draw_string( GR_DKC2_FONT, s->game_score_str, 14, 14, 0, ANIMATION_NONE);
 372     font_draw_string( GR_DKC2_FONT, s->sets_score_str, (WIDTH-font_get_string_width( GR_DKC2_FONT, s->sets_score_str))-14, 14, 0, ANIMATION_NONE);
 373
 374     font_draw_string( GR_DKC2_FONT, s->status, (WIDTH-font_get_string_width( GR_DKC2_FONT, s->status))/2, HEIGHT-50, s->time/30, ANIMATION_WAVE);
 375
 376 #ifdef DEBUG
 377     line_horiz( s->player1.y, 255, 0, 0);
 378     line_horiz( s->player2.y, 0, 0, 255);
 379     line_horiz( s->ball.y, 0, 255, 0);
 380
 381     line_vert( s->player1.x, 255, 0, 0);
 382     line_vert( s->player2.x, 0, 0, 255);
 383     line_vert( s->ball.x, 0, 255, 0);
 384
 385     line_horiz( s->player1.ball_dest, 255, 0, 255);
 386     line_horiz( s->player2.ball_dest, 0, 255, 255);
 387
 388     line_horiz( GAME_Y_MIN, 100, 100, 100);
 389     line_horiz( GAME_Y_MAX, 100, 100, 100);
 390 #endif
 391
 392     updatescr();
 393 }
 394
 395 void limit_value( float* value, float min, float max) {
 396     if( *value < min) {
 397         *value = min;
 398     } else if( *value > max) {
 399         *value = max;
 400     }
 401 }
 402
 403 float get_phase( GameState* s) {
 404     float pos, fract;
 405     float x, min, max, direction;
 406
 407     x = s->ball.x;
 408     min = GAME_X_MIN;
 409     max = GAME_X_MAX;
 410     direction = s->ball.move_x;
 411
 412     pos = (direction>0)?(1-GROUND_PHASE):(GROUND_PHASE);
 413
 414     fract = (x-min)/(max-min);
 415
 416     if( fract < pos) {
 417         fract = fract/pos;
 418         return fabsf( cosf(PI*fract/2))*PHASE_AMP*s->ball.jump;
 419     } else {
 420         fract = (pos-fract)/(1-pos);
 421         return fabsf( sinf(PI*fract/2))*PHASE_AMP*s->ball.jump;
 422     }
 423 }
 424
 425 float get_move_y( GameState* s, unsigned char player) {
 426     float pct, dest, x_len, y_len;
 427     float py, by, pa, move_x;
 428
 429     py = (player==1)?(s->player1.y):(s->player2.y);
 430     by = s->ball.y;
 431     pa = RACKET_Y_MID*2;
 432     move_x = s->ball.move_x;
 433
 434     /* -1.0 .. 1.0 for racket hit position */
 435     pct = (by-py)/(pa/2);
 436     limit_value( &pct, -1.0, 1.0);
 437
 438     /* Y destination for ball */
 439     dest = GAME_Y_MID + pct*(GAME_Y_MAX-GAME_Y_MIN);
 440     if( player == 1) {
 441         s->player1.ball_dest = dest;
 442     } else {
 443         s->player2.ball_dest = dest;
 444     }
 445
 446     /* lengths for the ball's journey */
 447     if( player == 1) {
 448         x_len = fabsf(GAME_X_MAX - s->ball.x);
 449         y_len = dest - by + MOVE_Y_SEED-rand()%MOVE_Y_SEED*2;
 450     } else {
 451         x_len = s->ball.x - GAME_X_MIN;
 452         y_len = by - dest + MOVE_Y_SEED-rand()%MOVE_Y_SEED*2;
 453     }
 454
 455     /* return the should-be value for move_y */
 456     return (y_len*move_x)/(x_len);
 457 }
 458
 459 void input_human( Player* player, bool up, bool down, bool hit, bool use_mouse, GameState* s) {
 460     int diff = PLAYER_MOVE_Y;
 461     int mb;
 462
 463     if (use_mouse) {
 464         mb = SDL_GetMouseState(&(player->mouse_x), &(player->mouse_y));
 465         if (mb&SDL_BUTTON(SDL_BUTTON_LEFT)) {
 466             hit = true;
 467         }
 468         if (player->mouse_y < player->y) {
 469             down = false;
 470             up = true;
 471             diff = (player->y-player->mouse_y<diff)?(player->y-player->mouse_y):(diff);
 472         } else if (player->mouse_y > player->y) {
 473             up = false;
 474             down = true;
 475             diff = (player->mouse_y-player->y<diff)?(player->mouse_y-player->y):(diff);
 476         }
 477     }
 478
 479     if (fabsf(s->joystick_y) > JOYSTICK_TRESHOLD) {
 480         diff = PLAYER_MOVE_Y*fabsf(s->joystick_y)/40.0;
 481         if (diff > PLAYER_MOVE_Y) {
 482             diff = PLAYER_MOVE_Y;
 483         }
 484     }
 485
 486     if (up) {
 487         player->y -= fminf(diff, diff*player->accelerate);
 488         player->accelerate *= PLAYER_ACCEL_INCREASE;
 489     } else if (down) {
 490         player->y += fminf(diff, diff*player->accelerate);
 491         player->accelerate *= PLAYER_ACCEL_INCREASE;
 492     } else {
 493         player->accelerate = PLAYER_ACCEL_DEFAULT;
 494     }
 495
 496     if( hit) {
 497         if( !player->state && !player->state_locked) {
 498             player->state = PLAYER_STATE_MAX;
 499             player->state_locked = true;
 500         }
 501     } else {
 502         player->state_locked = false;
 503     }
 504 }
 505
 506 void input_ai( Player* player, Ball* ball, Player* opponent, GameState* s) {
 507     float fact = 1.7;
 508     float target;
 509
 510     if( fabsf( player->y - ball->y) > RACKET_Y_MID*5) {
 511         fact = 3.5;
 512     }
 513
 514     target = GAME_Y_MID + (opponent->ball_dest - GAME_Y_MID)/5;
 515
 516     if( player->responsible) {
 517         if( player->desire == DESIRE_NORMAL && !IS_NEAR_Y_AI( player->y, ball->y)) {
 518             if( player->y < ball->y) {
 519                 player->y += fmin( 2*fact, ball->y - player->y);
 520             } else if( player->y > ball->y) {
 521                 player->y -= fmin( 2*fact, player->y - ball->y);
 522             }
 523         }
 524
 525         if( (ball->move_x != 0 || IS_NEAR_Y_AI( player->y, ball->y)) && IS_NEAR_X_AI( player->x, ball->x) && !player->state && rand()%4) {
 526             player->state = PLAYER_STATE_MAX;
 527         }
 528     } else if( ball->move_x == 0) {
 529         if( player->desire == DESIRE_NORMAL && !IS_NEAR_Y_AI( player->y, target)) {
 530             if( player->y < target) {
 531                 player->y += fmin( fact, (target-player->y)/40.0);
 532             } else if( player->y > target) {
 533                 player->y -= fmin( fact, (player->y-target)/40.0);
 534             }
 535         }
 536     } else if( s->ngram_prediction > 0.0) {
 537         target = s->ngram_prediction*((float)HEIGHT)/((float)(NGRAM_STEPS));
 538         target = GAME_Y_MID + (target-GAME_Y_MID)*1.5;
 539
 540         if( player->desire == DESIRE_NORMAL && !IS_NEAR_Y_AI( player->y, target)) {
 541             if( player->y < target) {
 542                 player->y += fmin( fact, (target-player->y)/40.0);
 543             } else if( player->y > target) {
 544                 player->y -= fmin( fact, (player->y-target)/40.0);
 545             }
 546         }
 547     } else {/*
 548         if( player->desire == DESIRE_NORMAL) {
 549             if( !IS_NEAR_Y_AI( player->y, target)) {
 550                 player->y += (target - player->y)/40.0;
 551             }
 552         }*/
 553     }
 554 }
 555
 556 void game_setup_serve( GameState* s) {
 557     s->ball.jump = 7.5;
 558     s->ball.y = GAME_Y_MID;
 559     s->ball.move_x = 0.0;
 560     s->ball.move_y = 0.0;
 561
 562     if( s->player1_serves) {
 563         s->player1.responsible = true;
 564         s->player1.ball_dest = 0.0;
 565         s->ball.x = GAME_X_MIN-RACKET_X_MID*1.5;
 566     } else {
 567         s->player1.responsible = false;
 568         s->player2.ball_dest = 0.0;
 569         s->ball.x = GAME_X_MAX+RACKET_X_MID*1.5;
 570     }
 571
 572     s->player2.responsible = !(s->player1.responsible);
 573 }
 574
 575 float ngram_predictor( GameState* s) {
 576     unsigned int count = 0;
 577     unsigned long sum = 0;
 578     int x, y, z;
 579     float result;
 580
 581     if( s->history_size < 3) {
 582         return 0.0;
 583     }
 584
 585     x = s->history[1];
 586     y = s->history[2];
 587
 588     for( z = 0; z<NGRAM_STEPS; z++) {
 589         count += s->ngram[x][y][z];
 590         sum += z * s->ngram[x][y][z];
 591     }
 592
 593     result = ((float)(sum))/((float)(count));
 594 #ifdef DEBUG
 595     printf( "predicting next = %.2f\n", result);
 596 #endif
 597
 598     return result;
 599 }
 600
 601 void score_game( GameState* s, bool player1_scored) {
 602     Player* winner = (player1_scored)?(&(s->player1)):(&(s->player2));
 603     Player* loser = (player1_scored)?(&(s->player2)):(&(s->player1));
 604
 605     if( s->current_set >= SETS_TO_WIN*2-1) {
 606         return;
 607     }
 608
 609     winner->game++;
 610     if( loser->game < winner->game-1) {
 611         if( winner->game >= 4) {
 612             winner->game = loser->game = 0;
 613             winner->sets[s->current_set]++;
 614             /* scoring the set.. */
 615             if( (winner->sets[s->current_set] == 6 && loser->sets[s->current_set] < 5) ||
 616                 winner->sets[s->current_set] == 7) {
 617                 s->current_set++;
 618                 s->winner = game_get_winner( s);
 619             }
 620         }
 621     }
 622 }
 623
 624 char* format_sets( GameState* s) {
 625     static char sets[100];
 626     static char tmp[100];
 627     int i, max = s->current_set;
 628
 629     sets[0] = '\0';
 630
 631     if( s->winner != WINNER_NONE) {
 632         max--;
 633     }
 634     for( i=0; i<=max; i++) {
 635         sprintf( tmp, "%d:%d, ", s->player1.sets[i], s->player2.sets[i]);
 636         strcat( sets, tmp);
 637     }
 638
 639     sets[strlen(sets)-2] = '\0';
 640
 641     return sets;
 642 }
 643
 644 char* format_game( GameState* s) {
 645     static char game[100];
 646     static const int game_scoring[] = { 0, 15, 30, 40 };
 647
 648     if( s->player1.game < 4 && s->player2.game < 4) {
 649         sprintf( game, "%d - %d", game_scoring[s->player1.game], game_scoring[s->player2.game]);
 650     } else if( s->player1.game > s->player2.game) {
 651         strcpy( game, "advantage player 1");
 652     } else if( s->player1.game < s->player2.game) {
 653         strcpy( game, "advantage player 2");
 654     } else {
 655         strcpy( game, "deuce");
 656     }
 657
 658     return game;
 659 }
 660
 661 char* format_status( GameState* s) {
 662     static char status[100];
 663     static const char* set_names[] = { "first", "second", "third", "fourth", "fifth" };
 664
 665     sprintf( status, "%d:%d in %s set", s->player1.sets[s->current_set], s->player2.sets[s->current_set], set_names[s->current_set]);
 666
 667     return status;
 668 }
 669
 670 int game_get_winner( GameState* s) {
 671     int i;
 672     int sets[2] = {0};
 673
 674     for( i=0; i<s->current_set; i++) {
 675         if( s->player1.sets[i] > s->player2.sets[i]) {
 676             sets[0]++;
 677         } else {
 678             sets[1]++;
 679         }
 680     }
 681
 682     if( sets[0] == SETS_TO_WIN) return WINNER_PLAYER1;
 683     if( sets[1] == SETS_TO_WIN) return WINNER_PLAYER2;
 684
 685     return WINNER_NONE;
 686 }
 687