game.c

   1 #include <stdio.h>
   2 #include <math.h>
   3
   4 #include "tennix.h"
   5 #include "game.h"
   6 #include "graphics.h"
   7 #include "input.h"
   8 #include "sound.h"
   9
  10 void game() {
  11     GameState s = {
  12         { GAME_X_MID, GAME_Y_MID, BALL_DEFAULT_SPEED, 0.2, 7.5 },
  13         { 0, 0, 0, 0, 0 },
  14         { GAME_X_MIN-4, GAME_Y_MID, 0, 0, 1 },
  15         { GAME_X_MAX, GAME_Y_MID, 0, 0, 0 },
  16         0,
  17         0,
  18         0,
  19     };
  20
  21     Uint32 ot = SDL_GetTicks();
  22     Uint32 nt;
  23     Uint32 dt = GAME_TICKS;
  24     Uint32 diff;
  25     Uint32 accumulator = 0;
  26     bool quit = false;
  27
  28     sound_audience();
  29
  30     while( !quit) {
  31         nt = SDL_GetTicks();
  32         diff = nt-ot;
  33         if( diff > 2000) {
  34             diff = 0;
  35         }
  36
  37         accumulator += diff;
  38         ot = nt;
  39
  40         while( accumulator >= dt) {
  41             quit = step( &s);
  42             s.time += dt;
  43             accumulator -= dt;
  44
  45             if( s.was_stopped) {
  46                 ot = SDL_GetTicks();
  47                 s.was_stopped = false;
  48             }
  49         }
  50
  51         render( &s);
  52     }
  53
  54 }
  55
  56 bool step( GameState* s) {
  57     Uint8 *keys;
  58     SDL_Event e;
  59
  60     if( get_phase( s) < 1.0) {
  61         if( !s->ground.jump) {
  62             sound_ground();
  63             /* after the ball hit the ground, responsibilities change */
  64             s->player1.responsible = !(s->player2.responsible = !s->player2.responsible);
  65         }
  66         s->ground.jump = 3;
  67         s->ground.x = s->ball.x;
  68         s->ground.y = s->ball.y;
  69     } else {
  70         if( s->ground.jump && !(s->time%5)) s->ground.jump--;
  71     }
  72
  73     if( IS_OUT_X(s->ball.x) || IS_OUT_Y(s->ball.y)) {
  74         if( (IS_OUT_Y(s->ball.y) && s->player1.responsible) || (!(s->player1.state && IS_NEAR_Y(s->player1.y, s->ball.y+get_phase( s))) && s->ball.x < GAME_X_MIN)) {
  75             s->player2.score++;
  76             sound_applause();
  77             s->player2.responsible = !(s->player1.responsible = 1);
  78             s->ball.x = GAME_X_MID;
  79             s->ball.y = GAME_Y_MID;
  80             s->ball.move_x = fabsf( s->ball.move_x);
  81             limit_value( &s->ball.move_x, s->ball.move_x, BALL_DEFAULT_SPEED);
  82             s->ball.move_y = -0.1;
  83             wait_keypress();
  84             s->was_stopped = true;
  85             sound_applause_stop();
  86         }
  87
  88         if( (IS_OUT_Y(s->ball.y) && s->player2.responsible) || (!(s->player2.state && IS_NEAR_Y(s->player2.y, s->ball.y+get_phase( s))) && s->ball.x > GAME_X_MAX)) {
  89             s->player1.score++;
  90             sound_applause();
  91             s->player1.responsible = !(s->player2.responsible = 1);
  92             s->ball.x = GAME_X_MID;
  93             s->ball.y = GAME_Y_MID;
  94             s->ball.move_x = -fabsf( s->ball.move_x);
  95             limit_value( &s->ball.move_x, -BALL_DEFAULT_SPEED, s->ball.move_x);
  96             s->ball.move_y = 0.1;
  97             wait_keypress();
  98             s->was_stopped = true;
  99             sound_applause_stop();
 100         }
 101
 102         if( IS_OUT_X(s->ball.x)) {
 103             if( s->ball.move_x < 0) {
 104                 s->ball.x = GAME_X_MIN;
 105                 if( s->player1.state == PLAYER_STATE_MAX) {
 106                     s->ball.move_x = PLAYER_POWERSHOT;
 107                 } else {
 108                     s->ball.move_x = 2.5 + 2.0*s->player1.state/PLAYER_STATE_MAX;
 109                 }
 110                 s->ball.move_y = get_move_y( s, 1);
 111                 s->ball.jump += 1.0-2.0*(s->player1.state<5);
 112                 sound_racket( s->player1.state == PLAYER_STATE_MAX);
 113             } else {
 114                 s->ball.x = GAME_X_MAX;
 115                 if( s->player2.state == PLAYER_STATE_MAX) {
 116                     s->ball.move_x = -PLAYER_POWERSHOT;
 117                 } else {
 118                     s->ball.move_x = -(2.5 + 2.0*s->player2.state/PLAYER_STATE_MAX);
 119                 }
 120                 s->ball.move_y = get_move_y( s, 2);
 121                 s->ball.jump += 1.0-2.0*(s->player2.state<5);
 122                 sound_racket( s->player2.state == PLAYER_STATE_MAX);
 123             }
 124         }
 125     }
 126
 127     s->ball.x += s->ball.move_x;
 128     s->ball.y += s->ball.move_y;
 129
 130     if( s->player1.state) s->player1.state--;
 131     if( s->player2.state) s->player2.state--;
 132
 133     SDL_PollEvent( &e);
 134     keys = SDL_GetKeyState( NULL);
 135
 136     if( keys['2']) s->player1.y-=8;
 137     if( keys['w']) s->player1.y-=6;
 138     if( keys['s']) s->player1.y+=6;
 139     if( keys['x']) s->player1.y+=8;
 140     if( keys['d'] && !s->player1.state) s->player1.state = PLAYER_STATE_MAX;
 141
 142     if( keys['9']) s->player2.y-=8;
 143     if( keys['o']) s->player2.y-=6;
 144     if( keys['l']) s->player2.y+=6;
 145     if( keys['.']) s->player2.y+=8;
 146     if( keys['k'] && !s->player2.state) s->player2.state = PLAYER_STATE_MAX;
 147
 148     if( keys['f']) SDL_WM_ToggleFullScreen( screen);
 149     if( keys['y']) SDL_SaveBMP( screen, "screenshot.bmp");
 150
 151     if( keys[SDLK_ESCAPE] || keys['q']) return true;
 152
 153     limit_value( &s->player1.y, PLAYER_Y_MIN, PLAYER_Y_MAX);
 154     limit_value( &s->player2.y, PLAYER_Y_MIN, PLAYER_Y_MAX);
 155     limit_value( &s->ball.jump, BALL_JUMP_MIN, BALL_JUMP_MAX);
 156
 157     return false;
 158 }
 159
 160 void render( GameState* s) {
 161     clearscr();
 162     show_image( GR_COURT, 0, 0, 255);
 163     show_image( GR_SHADOW, s->ball.x, s->ball.y, 255);
 164
 165     show_sprite( GR_RACKET, (!s->player1.state), 4, s->player1.x, s->player1.y, 255);
 166     show_sprite( GR_RACKET, (!s->player2.state)+2, 4, s->player2.x, s->player2.y, 255);
 167
 168     if( s->ground.jump) {
 169         show_sprite( GR_GROUND, s->ground.jump-1, 3, s->ground.x, s->ground.y, 128);
 170     }
 171
 172     if( s->ball.move_x > 0) {
 173         show_sprite( GR_BALL, (s->time/1000)%4, 4, s->ball.x, s->ball.y - get_phase( s), 255);
 174     } else {
 175         show_sprite( GR_BALL, 3-(s->time/1000)%4, 4, s->ball.x, s->ball.y - get_phase( s), 255);
 176     }
 177
 178     show_digit( s->player1.score/10%10, 140*2, 14, 100);
 179     show_digit( s->player1.score%10, 148*2, 14, 100);
 180     show_digit( 10, 156*2, 14, 100);
 181     show_digit( s->player2.score/10%10, 164*2, 14, 100);
 182     show_digit( s->player2.score%10, 172*2, 14, 100);
 183
 184     updatescr();
 185 }
 186
 187 void limit_value( float* value, float min, float max) {
 188     if( *value < min) {
 189         *value = min;
 190     } else if( *value > max) {
 191         *value = max;
 192     }
 193 }
 194
 195 float get_phase( GameState* s) {
 196     float pos, fract;
 197     float x, min, max, direction;
 198
 199     x = s->ball.x;
 200     min = GAME_X_MIN;
 201     max = GAME_X_MAX;
 202     direction = s->ball.move_x;
 203
 204     pos = (direction>0)?(1-GROUND_PHASE):(GROUND_PHASE);
 205
 206     fract = (x-min)/(max-min);
 207
 208     if( fract < pos) {
 209         fract = fract/pos;
 210         return fabsf( cosf(PI*fract/2))*PHASE_AMP*s->ball.jump;
 211     } else {
 212         fract = (pos-fract)/(1-pos);
 213         return fabsf( sinf(PI*fract/2))*PHASE_AMP*s->ball.jump;
 214     }
 215 }
 216
 217 float get_move_y( GameState* s, unsigned char player) {
 218     float pct, dest, x_len, y_len;
 219     float py, by, pa, move_x, phase;
 220
 221     if( player == 1) {
 222         py = s->player1.y;
 223     } else {
 224         py = s->player2.y;
 225     }
 226     by = s->ball.y - get_phase( s);
 227     pa = PLAYER_AREA;
 228     move_x = s->ball.move_x;
 229     phase = get_phase( s);
 230
 231     /* 0.0 .. 1.0 for racket hit position */
 232     pct = ((py+pa)-by)/(2*pa);
 233     limit_value( &pct, 0.0, 1.0);
 234
 235     /* Y destination for ball */
 236     dest = GAME_Y_MIN + pct*(GAME_Y_MAX-GAME_Y_MIN);
 237
 238     /* lengths for the ball's journey */
 239     x_len = GAME_X_MAX - GAME_X_MIN;
 240     y_len = dest - py + phase;
 241
 242     /* return the should-be value for move_y */
 243     return (y_len*move_x)/(x_len);
 244 }
 245