common/vision.h

   1 /***********************************************************************
   2  Freeciv - Copyright (C) 1996 - A Kjeldberg, L Gregersen, P Unold
   3    This program is free software; you can redistribute it and/or modify
   4    it under the terms of the GNU General Public License as published by
   5    the Free Software Foundation; either version 2, or (at your option)
   6    any later version.
   7
   8    This program is distributed in the hope that it will be useful,
   9    but WITHOUT ANY WARRANTY; without even the implied warranty of
  10    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11    GNU General Public License for more details.
  12 ***********************************************************************/
  13 #ifndef FC__VISION_H
  14 #define FC__VISION_H
  15
  16 #ifdef __cplusplus
  17 extern "C" {
  18 #endif /* __cplusplus */
  19
  20 #include "fc_types.h"
  21
  22 #include "improvement.h"                /* bv_imprs */
  23
  24 /****************************************************************************
  25   Vision for cities and units:
  26
  27   A vision source has a fixed owner and tile; it changes only in range.
  28   Vision range is given in radius squared; most such values will come from
  29   the ruleset.  All vision is circular.
  30
  31   A vision source is created using vision_new; this creates the source
  32   without any sight points.  Call vision_change_sight to change the sight
  33   points of a vision source (generally called from city_refresh_vision
  34   and unit_refresh vision; this can be called liberally to do updates after
  35   an effect may have changed the source's vision range).  Clear the sight
  36   using vision_clear_sight before freeing it with vision_free.
  37
  38   vision_get_sight returns the sight points of the source.  This should
  39   only rarely be necessary since all fogging and unfogging operations
  40   are taken care of internally.
  41
  42   vision_reveal_tiles() controls whether the vision source can discover
  43   new (unknown) tiles or simply maintain vision on already-known tiles.
  44   By default, cities should pass FALSE for this since they cannot
  45   discover new tiles.
  46
  47   ***** IMPORTANT *****
  48   To change any of the parameters given to vision_new - that is, to change
  49   the vision source's position (tile) or owner - you must create a new
  50   vision and then clear and free the old vision.  Order is very important
  51   here since you do not want to fog tiles intermediately.  You must store
  52   a copy of the old vision source, then create and attach and fill out the
  53   sight for a new vision source, and only then may you clear and free the
  54   old vision source.  In most operations you'll want to stick some other
  55   code in between so that for the bulk of the operation all tiles are
  56   visible.  For instance to move a unit:
  57
  58     old_vision = punit->server.vision;
  59     punit->server.vision = vision_new(unit_owner(punit), dest_tile);
  60     vision_change_sight(punit->server.vision,
  61                         get_unit_vision_at(punit, dest_tile));
  62
  63     ...then do all the work of moving the unit...
  64
  65     vision_clear_sight(old_vision);
  66     vision_free(old_vision);
  67
  68   note that for all the code in the middle both the new and the old
  69   vision sources are active.  The same process applies when transferring
  70   a unit or city between players, etc.
  71 ****************************************************************************/
  72
  73 /* Invariants: V_MAIN vision ranges must always be more than V_INVIS
  74  * ranges. */
  75 enum vision_layer {
  76   V_MAIN,
  77   V_INVIS,
  78   V_COUNT
  79 };
  80
  81 #define vision_layer_iterate(v) {                                           \
  82   enum vision_layer v;                                                      \
  83   for (v = 0; v < V_COUNT; v++) {
  84 #define vision_layer_iterate_end }}
  85
  86
  87 typedef short int v_radius_t[V_COUNT];
  88
  89 struct vision {
  90   /* These values cannot be changed after initialization. */
  91   struct player *player;
  92   struct tile *tile;
  93   bool can_reveal_tiles;
  94
  95   /* The radius of the vision source. */
  96   v_radius_t radius_sq;
  97 };
  98
  99 /* Initialize a vision radius array. */
 100 #define V_RADIUS(main_sq, invis_sq) { (main_sq), (invis_sq) }
 101
 102 #define ASSERT_VISION(v)                                                \
 103  do {                                                                   \
 104    fc_assert((v)->radius_sq[V_MAIN] >= (v)->radius_sq[V_INVIS]);        \
 105  } while (FALSE);
 106
 107 struct vision *vision_new(struct player *pplayer, struct tile *ptile);
 108 void vision_free(struct vision *vision);
 109
 110 bool vision_reveal_tiles(struct vision *vision, bool reveal_tiles);
 111
 112 /* This is copied in maphand.c really_give_tile_info_from_player_to_player(),
 113  * so be careful with pointers!
 114  */
 115 struct vision_site {
 116   char name[MAX_LEN_NAME];
 117   struct tile *location; /* Cannot be NULL */
 118   struct player *owner;  /* May be NULL, always check! */
 119
 120   int identity;          /* city > IDENTITY_NUMBER_ZERO */
 121   citizens size;         /* city size (0 <= size <= MAX_CITY_SIZE) */
 122
 123   bool occupied;
 124   bool walls;
 125   bool happy;
 126   bool unhappy;
 127   int style;
 128   int city_image;
 129
 130   bv_imprs improvements;
 131 };
 132
 133 #define vision_site_owner(v) ((v)->owner)
 134 void vision_site_destroy(struct vision_site *psite);
 135 struct vision_site *vision_site_new(int identity, struct tile *location,
 136                                     struct player *owner);
 137 struct vision_site *vision_site_new_from_city(const struct city *pcity);
 138 void vision_site_update_from_city(struct vision_site *psite,
 139                                   const struct city *pcity);
 140
 141 citizens vision_site_size_get(const struct vision_site *psite);
 142 void vision_site_size_set(struct vision_site *psite, citizens size);
 143
 144 #ifdef __cplusplus
 145 }
 146 #endif /* __cplusplus */
 147
 148 #endif  /* FC__VISION_H */