game.c

/*------------------------------------------------------------------
  game.c:

    XINVADERS 3D - 3d Shoot'em up
    Copyright (C) 2000 Don Llopis

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

------------------------------------------------------------------*/
#include "game.h"
#include "gtext.h"

#define SW_UPDATE  gv->sw_t += gv->msec
#define SW_PAUSE   gv->sw_save = gv->sw_t
#define SW_UNPAUSE gv->sw_t = gv->sw_save
#define SW_RESET   gv->sw_t = gv->sw_save = 0

static void  Add_obj_2_world ( OBJECT * );
static void  Clear_obj_list ( void );
static void  Sort_obj_list ( void );
static void  Draw_obj_list ( MATRIX4 );
static int   Z_compare ( const void *obj0, const void *obj1 );
static float Dist_pt_2_line ( VECTOR4 p, VECTOR4 l0, VECTOR4 l1 );

static void  Draw_vector_font ( int *s[], int x, int y, unsigned int color );

/*------------------------------------------------------------------
 * Variables
 *
 *
------------------------------------------------------------------*/

GAMEVARS gvars, *gv;
TIMER    gtimer, *gt;

static long
score_table[ZONE_HEIGHT_MAX] = { 10L, 50L, 100L, 150L, 200L };

/*================================================================*/

void Game_main ( void )
{
   while ( Handle_events() )
   {
      /* get start-time of current frame */
      gv->msec    = Timer_msec ( gt );
      gv->ftime   = (double)gv->msec/1000L;
      gv->fps     = 1.0 / gv->ftime;
      gv->fadjust = gv->rfps / gv->fps;

      (*Game_actionfn)();

      Update_display ();
   }
}

/*================================================================*/

void (*Game_actionfn) ();

/*================================================================*/

int Game_init ( float win_width, float win_height )
{
   /* initialize variables and timers */
   gv = &gvars;
   Game_init_vars ( INITGAME );
   Game_init_keys ();

   Stars_init ();
   Jumpgate_init ();
   Camera_init ( win_width, win_height, 0.785398163 );

   gt = &gtimer;
   Timer_init( gt );

   /* setup stopwatch timer and run menu */
   SW_RESET;
   Game_actionfn = Game_menu;

   return TRUE;
}

/*================================================================*/

void Game_init_vars ( int init_type )
{
   /* Help me! I'm using the evil goto !!! */
   switch ( init_type )
   {
      case INITGAME:
         gv->rfps         = REFERENCE_FRAMERATE;
         gv->display_fps  = FALSE;
         gv->hi_score     = HISCORE;

      case NEWGAME:
         gv->paused       = FALSE;
         gv->gameover     = FALSE;
         gv->pscore       = 0;
         gv->pbonus       = 0;
         gv->plives       = PLAYER_LIVES_START;

      case NEWLEVEL:
         gv->fcount       = 0;
         gv->msec         = 0;
         gv->ftime        = 0.0;
         gv->fps          = 0.0;
         gv->fadjust      = 0.0;
         gv->new_level    = FALSE;

      default:
      break;
   }
}

/*================================================================*/

void Game_init_keys ( void )
{
   gv->key_QUIT  = FALSE;
   gv->key_FIRE  = FALSE;
   gv->key_UP    = FALSE;
   gv->key_DOWN  = FALSE;
   gv->key_LEFT  = FALSE;
   gv->key_RIGHT = FALSE;
}

/*================================================================*/

void Game_newlevel ( void )
{
   srand ( time( NULL ) );
   Game_init_vars ( NEWLEVEL );
   Game_init_keys ();

   Stars_init ();
   Explosions_clear ();
   Jumpgate_init ();
   One_up_init ();

   Player_init ();
   Aliens_init ();

   SW_RESET;
   Game_actionfn = Game_ready;
}

/*================================================================*/

void Game_menu ( void )
{
   static int blink = 0;
   static int color = 0;
   int        i, *tmp_score[20];
   char       buffer[256], tmp_num[2];

   VECTOR4 up = { 0.0f, 1.0f, 0.0f, 1.0f };
   VECTOR4 from = { 0.0f, 0.0f, 100.0f, 1.0f };
   VECTOR4 at = { 0.0f, 0.0f, 0.0f, 1.0f };
   MATRIX4 cam_mat;

   /* convert hi-score into a vector-font */
   sprintf ( buffer, "%ld", gv->hi_score );
   tmp_num[0] = '0';
   tmp_num[1] = '\0';
   for ( i=0; buffer[i]; i++ )
   {
      tmp_num[0] = buffer[i];
      tmp_score[i] = NUMBER[atoi(tmp_num)];
   }
   tmp_score[strlen(buffer)] = NULL;
   Draw_vector_font ( HI_SCORE, 120, 15, GREEN );
   Draw_vector_font ( tmp_score, 360, 15, GREEN );

   Camera_transform ( cam_mat, up, from, at );
   Stars_draw ( cam_mat );

   blink += gv->msec;
   if ( blink > 250 )
   {
      color++;
      blink -= 250;
      if ( color > 3 ) color = 0;
   }

   i = RED - ( color * 15 );

   Draw_vector_font ( XINVADERS3D_LOGO, 155, 150, GREEN );
   Draw_vector_font ( PRESS, 40, 400, i );
   Draw_vector_font ( FIRE, 220, 400, i );
   Draw_vector_font ( TO, 370, 400, i );
   Draw_vector_font ( START, 460, 400, i );

   if ( gv->key_FIRE )
   {
      Game_actionfn = Game_newlevel;
   }
}

/*================================================================*/

void Game_ready ( void )
{
   static int blink = 0;
   static int color = 0;
   int i;

   VECTOR4 up = { 0.0f, 1.0f, 0.0f, 1.0f };
   VECTOR4 from = { 0.0f, 0.0f, 100.0f, 1.0f };
   VECTOR4 at = { 0.0f, 0.0f, 0.0f, 1.0f };
   MATRIX4 cam_mat;

   Camera_transform ( cam_mat, up, from, at );
   Stars_draw ( cam_mat );

   blink += gv->msec;
   if ( blink > 250 )
   {
      blink -= 250;
      color++;
      if ( color == 3 )
         color = 0;
   }

   i = RED - ( color * 15 );
   Draw_vector_font ( GET, 140, 200, i );
   Draw_vector_font ( READY, 260, 200, i );

   Game_overlay ();
   SW_UPDATE;

   if ( gv->key_FIRE || gv->sw_t > READY_TIME )
   {
      SW_RESET;
      Game_actionfn = Game_run;
   }
}

/*================================================================*/

void Game_paused_toggle ( void )
{
   static void (*saved_action_fn)( void ) = NULL;

   gv->paused ^= TRUE;

   if ( gv->paused )
   {
      SW_PAUSE;
      saved_action_fn = Game_actionfn;
      Game_actionfn = Game_paused;
   }
   else
   {
      SW_UNPAUSE;
      Game_actionfn = saved_action_fn;
   }
}

void Game_paused ( void )
{
   VECTOR4 up = { 0.0f, 1.0f, 0.0f, 1.0f };
   VECTOR4 from = { 0.0f, 0.0f, 100.0f, 1.0f };
   VECTOR4 at = { 0.0f, 0.0f, 0.0f, 1.0f };
   MATRIX4 cam_mat;

   Camera_transform ( cam_mat, up, from, at );
   Stars_draw ( cam_mat );
   Draw_vector_font ( PAUSED, 230, 200, RED );

   Game_overlay ();
   SW_UPDATE;
}

/*================================================================*/

void Game_reset ( void )
{
   SW_RESET;
   Game_init_vars ( INITGAME );
   Game_init_keys ();
   Game_actionfn = Game_menu;
}

void Game_gameover ( void )
{
   VECTOR4 up = { 0.0f, 1.0f, 0.0f, 1.0f };
   VECTOR4 from = { 0.0f, 0.0f, 100.0f, 1.0f };
   VECTOR4 at = { 0.0f, 0.0f, 0.0f, 1.0f };
   MATRIX4 cam_mat;

   Camera_transform ( cam_mat, up, from, at );
   Stars_draw ( cam_mat );
   Draw_vector_font ( GAME, 165, 200, RED );
   Draw_vector_font ( OVER, 315, 200, RED );
   Game_overlay ();
   SW_UPDATE;

   if ( gv->key_FIRE || (gv->sw_t > GAMEOVER_TIME) )
   {
      SW_RESET;
      Game_init_vars ( NEWGAME );
      Game_init_keys ();
      Game_actionfn = Game_menu;
   }
}

/*================================================================*/

void Game_overlay ( void )
{
   char buffer[256], tmp_num[2];
   int  i, x, *tmp_score[20];
   int  life[6] = { 0, 450, 25, 450, 12, 425 };

   if ( gv->display_fps )
   {
      if ( gv->ftime > 0.0f )
      {
         sprintf ( buffer, "FPS:%3.0f:(%1.3f):ms(%ld)", gv->fps,
                            gv->fadjust,gv->msec );
      }
      else
         sprintf ( buffer, "FPS: n/a" );

      Draw_text ( buffer, 0, 475, RED );
   }

   /* convert score into a vector-font */
   sprintf ( buffer, "%ld", gv->pscore );
   tmp_num[0] = '0';
   tmp_num[1] = '\0';
   for ( i=0; buffer[i]; i++ )
   {
      tmp_num[0] = buffer[i];
      tmp_score[i] = NUMBER[atoi(tmp_num)];
   }
   tmp_score[strlen(buffer)] = NULL;
   Draw_vector_font ( SCORE, 150, 14, GREEN );
   Draw_vector_font ( tmp_score, 330, 15, GREEN );

   x=15;
   i = gv->plives;
   while ( --i > 0 )
   {
      Draw_line ( life[0]+x, life[1], life[2]+x, life[3], GREEN );
      Draw_line ( life[2]+x, life[3], life[4]+x, life[5], GREEN );
      Draw_line ( life[4]+x, life[5], life[0]+x, life[1], GREEN );
      x+= 30;
   }
#ifdef GAME_DEBUG
   sprintf ( buffer, "Lives: %d", gv->plives-1 );
   Draw_text ( buffer, 550, 470, GREEN );

   sprintf ( buffer, "Time: %10.0fs", (double)gv->sw_t/1000);
   Draw_text ( buffer, 0, 470, RED );

   sprintf ( buffer, "U: %d D: %d L: %d R: %d F: %d",
         gv->key_UP, gv->key_DOWN, gv->key_LEFT, gv->key_RIGHT,
         gv->key_FIRE );
   Draw_text ( buffer, 200, 470, WHITE );
#endif
}

/*================================================================*/

void Game_run ( void )
{
   float  dist = 0.0f;
   OBJECT *alien, *abomb;
   VECTOR4    up = { 0.0f, 1.0f, 0.0f, 1.0f };
   VECTOR4    from = { 0.0f, 25.0f, 100.0f, 1.0f };
   VECTOR4    at = { 0.0f, 0.0f, -100.0f, 1.0f };
   MATRIX4    cam_mat;

   /* prepare for new frame */
   Clear_obj_list ();

   /* update-player */
   if ( player->active )
      player->actionfn ( player );

   /* update camera */
   Vector_addd ( from, player->pos );
   Vector_addd ( at, player->pos );
   Camera_transform ( cam_mat, up, from, at );

   /*
    * Do collisions checking :
    * player_missile vs aliens
    * player vs alien(s)
    * alien bombs vs player
    */

   if ( pm->active )
   {
      /* is player missile in the formation zone ?? */
      if ( pm->zone == gv->formation_zone )
      {
         if ( ( pm->zheight > -1 ) && (pm->zheight < ZONE_HEIGHT_MAX ) )
         {
            /* if so which height-level??             */
            alien = (af_list+pm->zheight)->head;
            while ( alien )
            {
               dist = Dist_pt_2_line ( alien->pos, pm->old_pos, pm->pos ) -
                  pm->radius_squared - 1.0f;

               if ( dist < alien->radius_squared )
               {
                  pm->active = alien->active = FALSE;
                  gv->alien_count--;
                  Objlist_del    ( (af_list+pm->zheight), alien );
                  Explosions_add ( alien );
                  Aliens_update  ( alien );

                  /* update player score & alien count */
                  gv->pscore += score_table[pm->zheight];
                  gv->pbonus += score_table[pm->zheight];
                  if ( gv->pbonus > PLAYER_LIFE_BONUS-1 )
                  {
                     gv->pbonus -= PLAYER_LIFE_BONUS;
                     if ( gv->plives < PLAYER_LIFE_MAX )
                     {
                        gv->plives++;
                        One_up_add ( alien );
                     }
                  }
                  if ( gv->alien_count == 0 )
                     gv->new_level = TRUE;

                  break;
               }
               alien = alien->next;
            }
         }
      }
      /* is player missile in the UFO zone?? */
      else
      {
         if ( (ufo->active)
            &&  ( pm->zone == ufo->zone )
            && ( pm->zheight == ufo->zheight ) )
         {
            dist = Dist_pt_2_line ( ufo->pos, pm->old_pos, pm->pos ) -
              pm->radius_squared - 1.0f;
            if ( dist < ufo->radius_squared )
            {
               pm->active = ufo->active = FALSE;
               Explosions_add ( ufo );

               /* update player score */
               gv->pscore += UFO_BONUS;
               gv->pbonus += UFO_BONUS;
               if ( gv->pbonus > PLAYER_LIFE_BONUS-1 )
               {
                  gv->pbonus -= PLAYER_LIFE_BONUS;
                  if ( gv->plives < PLAYER_LIFE_MAX )
                  {
                     gv->plives++;
                     One_up_add ( ufo );
                  }
               }
            }
         }
      }

   }

   /* alien bombs vs player */
   if ( player->active && !gv->gameover && !gv->pblinking )
   {
      for (abomb=abombs->head; abomb != NULL; abomb=abomb->next )
      {
         if ( (abomb->zone == player->zone) &&
              (abomb->zheight == player->zheight) )
         {
            dist = Dist_pt_2_line ( player->pos, abomb->old_pos, abomb->pos ) -
               abomb->radius_squared - 1.0f;
            if ( dist < player->radius_squared )
            {
               abomb->active = player->active = FALSE;
               Explosions_add ( player );
               Objlist_del ( abombs, abomb );

               break;
            }
         }
      }
   }

   /*
    * player vs aliens:
    * if the remaining aliens reach the player_zone
    * then the game is over! Reduce the number of
    * remaining lives to zero and blowup the player and
    * then initiate a game-over!
    */

   if ( gv->formation_zone == ZONE_0 )
   {
      gv->plives   = 0;
      if ( player->active )
      {
         Explosions_add ( player );
         player->active = FALSE;
      }
   }

   /*
    *
    * Move Objects and Update Animations :
    * formation, alien_bombs, ufo, and player_missile
    *
    */
   Aliens_move ();

   if ( pm->active )
      pm->actionfn ( pm );

   /*
    *
    *  Draw Objects :
    *
    *  special effects
    *  alien: formation, bombs, and ufo
    *  player missile
    *  player
    *
    */

   Stars_draw ( cam_mat );
   Jumpgate_animate ( cam_mat );
   Explosions_draw ( cam_mat );
   One_up_draw ( cam_mat );

   /*
    * major hack!! this is NOT the right way to draw in 3d
    * may the universe forgive my transgression!
    *
    * */
   if ( ufo->active )
      Add_obj_2_world ( ufo );
   Add_obj_2_world ( &the_formation );

   for (abomb=abombs->head; abomb != NULL; abomb=abomb->next )
   {
      Add_obj_2_world ( abomb );
   }

   if ( pm->active )
      Add_obj_2_world ( pm );
   if ( player->active )
      Add_obj_2_world ( player );

   Sort_obj_list ();
   Draw_obj_list ( cam_mat );

   SW_UPDATE;
   Game_overlay ();

   /*
    *  Before acknowledging flags make sure ALL explosions
    *  are finished:
    *  gameover flag has precedence over newlevel flag
    *  since it is possible for a player to have killed
    *  all the aliens but then get killed by an alien bomb
    *  resulting in both a newlevel and gameover condition!!
    */
   if ( Explosions_count() == 0 )
   {
      if ( player->active == FALSE )
      {
         /* reduce player life and check for gameover */
         gv->plives--;
         if ( gv->plives <= 0 )
            gv->gameover = TRUE;

         Player_init ();
         SW_RESET;
         Game_actionfn = Game_ready;
      }

      if ( gv->gameover )
      {
         if ( gv->pscore > gv->hi_score )
            gv->hi_score = gv->pscore;

         SW_RESET;
         Game_actionfn = Game_gameover;
      }
      else
      {
         if ( gv->new_level && ( Objlist_count ( abombs ) == 0 ) )
         {
            SW_RESET;
            Game_actionfn = Game_newlevel;
         }
      }
   }
}

/*================================================================*/

void Object_update_zone ( OBJECT *obj )
{
   obj->zone    = (int) floor ( (double)obj->pos[ZPOS]/-ZONE_WIDTH  );
   obj->zheight = (int) floor ( (double)obj->pos[YPOS]/ZONE_HEIGHT );
}

/*================================================================*/

static void Draw_vector_font ( int *s[], int x, int y, unsigned int color )
{
   int *letter, segments, x1, y1, x2, y2;

   while ( (letter=*s++) ) {
      /* first integer of pointer array is always # of line segments */
      segments=*letter++;
      while ( --segments>=0 ) {
         x1 = (*letter++)+x; y1 = (*letter++)+y;
         x2 = (*letter++)+x; y2 = (*letter++)+y;
         Draw_line( x1, y1, x2, y2, color );
      }
      x += 30;
   }
}

/*================================================================*/

void Add_obj_2_world ( OBJECT *obj )
{
   int i;

   i = gv->gobjcount;
   if ( i < MAX_OBJECTS-1 )
   {
      gv->gobjs[i] = obj;
      gv->gobjcount++;
   }
}

void Clear_obj_list ( void )
{
   gv->gobjcount = 0;
}

void Sort_obj_list ( void )
{
   qsort ( gv->gobjs, gv->gobjcount, sizeof ( OBJECT * ), Z_compare );
}

int Z_compare ( const void *obj0, const void *obj1 )
{
   OBJECT *o0, *o1;

   o0 = ( OBJECT * ) obj0;
   o1 = ( OBJECT * ) obj1;

   if ( o0->pos[ZPOS] < o1->pos[ZPOS] )
      return -1;
   else if ( o0->pos[ZPOS] > o1->pos[ZPOS] )
      return 1;
   else
      return 0;
}

void Draw_obj_list ( MATRIX4 r )
{
   int i;
   OBJECT *obj;

   i = 0;
   while ( i<gv->gobjcount )
   {
      obj = gv->gobjs[i++];
      obj->drawfn ( obj, r );
   }
}
/*================================================================*/

float Dist_pt_2_line ( VECTOR4 p, VECTOR4 l0, VECTOR4 l1 )
{
   VECTOR4 l0_p;
   VECTOR4 l0_l1;
   VECTOR4 q;
   float n, d, w, t, dist;

   /*
    * calc adjusted position of projectile along the
    * line segment formed by old_pos to new_pos
    * use this for calculating distance between moving
    * objects. This must be done since movement is
    * not in discreet amounts due to varying framerates.
    *
    * routine uses the properties of the unit vector
    * and dot product. see ``Computer Graphics:
    * principles and practice'' appendix for
    * explaination. Then checks to see if generated
    * line falls within the line segment l0l1
    *
    */

   Vector_sub ( p, l0, l0_p );
   Vector_sub ( l1, l0, l0_l1 );

   /*
    * don't try to take Vector_norm if division by zero
    * will result. TBB
    *
    * check using Vec_mag_squared instead of
    * xpos == 0 && ypos == 0 && zpos == 0
    * Don
    */

   if ( Vector_mag_squared ( l0_l1 ) < 1.0f )
   {
      q[XPOS] = l0[XPOS];
      q[YPOS] = l0[YPOS];
      q[ZPOS] = l0[ZPOS];

      dist = Vector_dist_squared ( q, p );
   }
   else
   {
      d = l1[ZPOS] - l0[ZPOS];

      /* l0 and l1 are very close */
      if ( (d > -0.025 ) && ( d < 0.025 ) )
      {
         q[XPOS] = l0[XPOS];
         q[YPOS] = l0[YPOS];
         q[ZPOS] = l0[ZPOS];

         dist = Vector_dist_squared ( q, p );
      }
      else
      {
         Vector_norm ( l0_l1 );
         w = Vector_dot ( l0_p, l0_l1 );

         q[XPOS] = l0[XPOS] + ( l0_l1[XPOS] * w );
         q[YPOS] = l0[YPOS] + ( l0_l1[YPOS] * w );
         q[ZPOS] = l0[ZPOS] + ( l0_l1[ZPOS] * w );

         n = q[ZPOS] - l0[ZPOS];

         t = n / d;
         if ( ( t > -0.025f ) && ( t < 1.5f ) )
            dist = Vector_dist_squared ( q, p );
         else
            dist = 1000000.0f;
      }
   }

   return dist;
}