Add threat level indicators for monsters

Webtiles and console both have a monster list at the bottom-right of
the screen which lists all monsters in view color-coded by rough
threat level. Many players have expressed a desire for something
similar in offline tiles, to provide always-visible indicators of the
threat levels of all enemies in view. This commit adds translucent
colored backgrounds -- dark grey, light grey, yellow, and red --
to indicate trivial, easy, tough, and nasty monsters respectively.

Additionally, these indicators are configurable with a new option in
the options file, "tile_show_threat_levels" with valid values being any set of 'trivial', 'easy', 'tough' and 'nasty'. Each type of indicator
can be independently enabled or disabled by including or omitting it
in the option file line. For example, the following...

"tile_show_threat_levels = tough nasty"

...will show only yellow (tough) and red (nasty) threat indicators.

This patch was mostly written by GnarledBeach in PR crawl#1120. I picked it up and added webtiles support, plus squashed some trivial commits.

crawl-ref/source/initfile.cc

@@ -320,6 +320,8 @@ const vector<GameOption*> game_options::build_options_list()
         new BoolGameOption(SIMPLE_NAME(tile_show_minihealthbar), true),
         new BoolGameOption(SIMPLE_NAME(tile_show_minimagicbar), true),
         new BoolGameOption(SIMPLE_NAME(tile_show_demon_tier), false),
+        new StringGameOption(SIMPLE_NAME(tile_show_threat_levels),
+            "trivial easy tough nasty"),
         new StringGameOption(SIMPLE_NAME(tile_show_items), "!?/%=([)x}:|\\"),
         // disabled by default due to performance issues
         new BoolGameOption(SIMPLE_NAME(tile_water_anim), !USING_WEB_TILES),

crawl-ref/source/menu.cc

@@ -1549,6 +1549,28 @@ bool MonsterMenuEntry::get_tiles(vector<tile_def>& tileset) const
         tileset.emplace_back(TILE_HALO_GD_NEUTRAL, TEX_FEAT);
     else if (m->neutral())
         tileset.emplace_back(TILE_HALO_NEUTRAL, TEX_FEAT);
+    else
+        switch (m->threat)
+        {
+        case MTHRT_TRIVIAL:
+            if (Options.tile_show_threat_levels.find("trivial") != string::npos)
+                tileset.emplace_back(TILE_BORDER_TRIVIAL, TEX_FEAT);
+            break;
+        case MTHRT_EASY:
+            if (Options.tile_show_threat_levels.find("easy") != string::npos)
+                tileset.emplace_back(TILE_BORDER_EASY, TEX_FEAT);
+            break;
+        case MTHRT_TOUGH:
+            if (Options.tile_show_threat_levels.find("tough") != string::npos)
+                tileset.emplace_back(TILE_BORDER_TOUGH, TEX_FEAT);
+            break;
+        case MTHRT_NASTY:
+            if (Options.tile_show_threat_levels.find("nasty") != string::npos)
+                tileset.emplace_back(TILE_BORDER_NASTY, TEX_FEAT);
+            break;
+        default:
+            break;
+        }
 
     if (m->type == MONS_DANCING_WEAPON)
     {

crawl-ref/source/options.h

@@ -569,6 +569,7 @@ struct game_options
     bool        tile_show_minihealthbar;
     bool        tile_show_minimagicbar;
     bool        tile_show_demon_tier;
+    string      tile_show_threat_levels;
     bool        tile_water_anim;
     bool        tile_misc_anim;
     vector<string> tile_layout_priority;

crawl-ref/source/rltiles/dc-feat.txt

@@ -673,6 +673,10 @@ halo_friendly HALO_FRIENDLY
 halo_gd_neutral HALO_GD_NEUTRAL
 halo_neutral HALO_NEUTRAL
 halo_summoner HALO_SUMMONER
+monster_threat_trivial BORDER_TRIVIAL
+monster_threat_easy BORDER_EASY
+monster_threat_tough BORDER_TOUGH
+monster_threat_nasty BORDER_NASTY
 ray RAY
 ray_multi RAY_MULTI
 ray_out_of_range RAY_OUT_OF_RANGE

crawl-ref/source/tile-flags.h

@@ -49,6 +49,13 @@ enum tile_flags ENUM_INT64
     TILE_FLAG_VILE_CLUTCH  = 0x400000000000000ULL,
     TILE_FLAG_POSSESSABLE  = 0x800000000000000ULL,
 
+    // 4 mutually exclusive flags for threat level.
+    TILE_FLAG_THREAT_MASK  = 0xE000000000000000ULL,
+    TILE_FLAG_TRIVIAL      = 0x2000000000000000ULL,
+    TILE_FLAG_EASY         = 0x4000000000000000ULL,
+    TILE_FLAG_TOUGH        = 0x6000000000000000ULL,
+    TILE_FLAG_NASTY        = 0x8000000000000000ULL,
+
     // MDAM has 5 possibilities, so uses 3 bits.
     TILE_FLAG_MDAM_MASK    = 0x1C0000000ULL,
     TILE_FLAG_MDAM_LIGHT   = 0x040000000ULL,

crawl-ref/source/tiledgnbuf.cc

@@ -362,6 +362,16 @@ void DungeonCellBuffer::pack_background(int x, int y, const packed_cell &cell)
                 else if (att_flag == TILE_FLAG_NEUTRAL)
                     m_buf_feat.add(TILE_HALO_NEUTRAL, x, y);
 
+                const tileidx_t threat_flag = cell.fg & TILE_FLAG_THREAT_MASK;
+                if (threat_flag == TILE_FLAG_TRIVIAL)
+                    m_buf_feat.add(TILE_BORDER_TRIVIAL, x, y);
+                else if (threat_flag == TILE_FLAG_EASY)
+                    m_buf_feat.add(TILE_BORDER_EASY, x, y);
+                else if (threat_flag == TILE_FLAG_TOUGH)
+                    m_buf_feat.add(TILE_BORDER_TOUGH, x, y);
+                else if (threat_flag == TILE_FLAG_NASTY)
+                    m_buf_feat.add(TILE_BORDER_NASTY, x, y);
+
                 if (cell.is_highlighted_summoner)
                     m_buf_feat.add(TILE_HALO_SUMMONER, x, y);
             }

crawl-ref/source/tilepick.cc

@@ -1933,6 +1933,29 @@ tileidx_t tileidx_monster(const monster_info& mons)
         ch |= TILE_FLAG_GD_NEUTRAL;
     else if (mons.neutral())
         ch |= TILE_FLAG_NEUTRAL;
+    else
+        switch (mons.threat)
+        {
+        case MTHRT_TRIVIAL:
+            if (Options.tile_show_threat_levels.find("trivial") != string::npos)
+                ch |= TILE_FLAG_TRIVIAL;
+            break;
+        case MTHRT_EASY:
+            if (Options.tile_show_threat_levels.find("easy") != string::npos)
+                ch |= TILE_FLAG_EASY;
+            break;
+        case MTHRT_TOUGH:
+            if (Options.tile_show_threat_levels.find("tough") != string::npos)
+                ch |= TILE_FLAG_TOUGH;
+            break;
+        case MTHRT_NASTY:
+            if (Options.tile_show_threat_levels.find("nasty") != string::npos)
+                ch |= TILE_FLAG_NASTY;
+            break;
+        default:
+            break;
+        }
+
     if (mons.is(MB_FLEEING))
         ch |= TILE_FLAG_FLEEING;
     else if (mons.is(MB_STABBABLE) || mons.is(MB_SLEEPING)

crawl-ref/source/webserver/game_data/static/cell_renderer.js

@@ -702,6 +702,16 @@ function ($, view_data, main, tileinfo_player, icons, dngn, enums,
                         else if (fg.NEUTRAL)
                             this.draw_dngn(dngn.HALO_NEUTRAL, x, y);
 
+                        // Monster difficulty
+                        if (fg.TRIVIAL)
+                            this.draw_dngn(dngn.BORDER_TRIVIAL, x, y);
+                        else if (fg.EASY)
+                            this.draw_dngn(dngn.BORDER_EASY, x, y);
+                        else if (fg.TOUGH)
+                            this.draw_dngn(dngn.BORDER_TOUGH, x, y);
+                        else if (fg.NASTY)
+                            this.draw_dngn(dngn.BORDER_NASTY, x, y);
+
                         if (cell.highlighted_summoner)
                             this.draw_dngn(dngn.HALO_SUMMONER, x, y);
                     }

crawl-ref/source/webserver/game_data/static/enums.js

@@ -207,6 +207,15 @@ define(function () {
     fg_flags.flags.PINNED       = [0, 0x2000000];
     fg_flags.flags.VILE_CLUTCH  = [0, 0x4000000];
 
+    // Threat level has 4 possibilities, so uses 3 bits.
+    fg_flags.exclusive_flags.push({
+        mask       : [0, 0x60000000 | highbit],
+        TRIVIAL    : [0, 0x20000000],
+        EASY       : [0, 0x40000000],
+        TOUGH      : [0, 0x60000000],
+        NASTY      : [0, highbit]
+    })
+
     // MDAM has 5 possibilities, so uses 3 bits.
     fg_flags.exclusive_flags.push({
         mask       : [0x40000000 | highbit, 0x01],