feat: allow treating steel targets as practice targets (#4143)

* feat: allow treating steel targets as practice targets

* Update json_flags.md

* style(autofix.ci): automated formatting

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

data/json/furniture_and_terrain/furniture-recreation.json

@@ -109,7 +109,7 @@
     "move_cost_mod": 2,
     "coverage": 40,
     "required_str": 5,
-    "flags": [ "PLACE_ITEM", "TRANSPARENT" ],
+    "flags": [ "PLACE_ITEM", "TRANSPARENT", "SHOOT_ME" ],
     "bash": {
       "str_min": 6,
       "str_max": 40,

doc/src/content/docs/en/mod/json/reference/json_flags.md

@@ -597,6 +597,8 @@ List of known flags, used in both `terrain.json` and `furniture.json`.
 - `SEALED` Can't use <kbd>e</kbd> to retrieve items; must smash them open first.
 - `SEEN_FROM_ABOVE` Visible from a higher level (provided the tile above has no floor)
 - `SHARP` May do minor damage to players/monsters passing through it.
+- `SHOOT_ME` Players can aim at terrain or furniture with this flag like they can with
+  `tr_practice_target` to train marksmanship.
 - `SHORT` Feature too short to collide with vehicle protrusions. (mirrors, blades).
 - `SIGN` Show written message on examine.
 - `SMALL_PASSAGE` This terrain or furniture is too small for large or huge creatures to pass

src/ranged.cpp

@@ -140,6 +140,9 @@ static const bionic_id bio_ups( "bio_ups" );
 static const trait_id trait_PYROMANIA( "PYROMANIA" );
 static const trait_id trait_NORANGEDCRIT( "NO_RANGED_CRIT" );
 
+// not to confuse with item flags (json_flag)
+static const std::string flag_SHOOT_ME( "SHOOT_ME" );
+
 // Maximum duration of aim-and-fire loop, in turns
 static constexpr int AIF_DURATION_LIMIT = 10;
 
@@ -2757,7 +2760,8 @@ tripoint target_ui::choose_initial_target()
     const std::vector<tripoint> nearby = closest_points_first( src, range );
     const auto target_spot = std::find_if( nearby.begin(), nearby.end(),
     [this, &here]( const tripoint & pt ) {
-        return here.tr_at( pt ).id == tr_practice_target && this->you->sees( pt );
+        return ( here.has_flag_ter_or_furn( flag_SHOOT_ME, pt ) ||
+                 here.tr_at( pt ).id == tr_practice_target ) && this->you->sees( pt );
     } );
     if( target_spot != nearby.end() ) {
         return *target_spot;