Mutation selection stops at certain points (#82649)

* First step

Update mutation.cpp

Update mutation.cpp

Update mutation.cpp

Update mutation.cpp

Update mutation.cpp

* Count Substitute Threshold traits

* Update mutation.cpp

* Apply suggestions from code review

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

* Update src/mutation.cpp

* Update src/mutation.cpp

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

* Update mutations.json

* Update mutation.cpp

* Apply suggestions from code review

Co-authored-by: ehughsbaird <[email protected]>

* Apply suggestions from code review

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

* Update mutation.cpp

* Update mutation.cpp

* Update src/mutation.cpp

* Update mutation.cpp

* Apply suggestions from code review

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

* Apply suggestions from code review

* Apply suggestions from code review

* Update src/mutation.cpp

* Apply suggestions from code review

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

* Update src/mutation.cpp

* Apply suggestions from code review

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

* Update src/mutation.cpp

* Apply suggestions from code review

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: ehughsbaird <[email protected]>

Author: 3 people

data/json/mutations/mutations.json

@@ -2206,7 +2206,9 @@
     "starting_trait": true,
     "cancels": [ "ROBUST", "RESTRICTED", "RESISTANT_GENETICS" ],
     "valid": false,
-    "vitamin_rates": [ [ "instability", -60 ] ]
+    "vitamin_rates": [ [ "instability", -60 ] ],
+    "category": [ "CHIMERA" ],
+    "threshreq": [ "THRESH_CHIMERA" ]
   },
   {
     "type": "mutation",
@@ -7778,6 +7780,7 @@
     "purifiable": false,
     "description": "Your body alters itself rapidly, and without your intervention or conscious control.",
     "prereqs": [ "UNSTABLE", "MUT_JUNKIE" ],
+    "changes_to": [ "CHAOTIC_BAD" ],
     "category": [ "CHIMERA" ]
   },
   {

src/character.cpp

@@ -730,6 +730,22 @@ bool Character::has_martialart( const matype_id &m ) const
     return martial_arts_data->has_martialart( m );
 }
 
+int Character::count_threshold_substitute_traits() const
+{
+    int count = 0;
+    for( const mutation_branch &mut : mutation_branch::get_all() ) {
+        if( !mut.threshold_substitutes.empty() && has_trait( mut.id ) &&
+            std::find_if( mut.threshold_substitutes.begin(), mut.threshold_substitutes.end(),
+        [this]( const trait_id & t ) {
+        return has_trait( t );
+        } ) != mut.threshold_substitutes.end() ) {
+            ++count;
+            break;
+        }
+    }
+    return count;
+}
+
 int Character::get_oxygen_max() const
 {
     return 30 + ( has_bionic( bio_synlungs ) ? 30 : 2 * str_cur );

src/character.h

@@ -648,6 +648,8 @@ class Character : public Creature, public visitable
         int get_arm_str() const;
         // Defines distance from which CAMOUFLAGE mobs are visible
         int get_eff_per() const override;
+        // Counts how many traits a character has via threshold substitution
+        int count_threshold_substitute_traits() const;
 
         // Penalty modifiers applied for ranged attacks due to low stats
         int ranged_dex_mod() const;

src/mutation.cpp

@@ -87,6 +87,7 @@ static const mutation_category_id mutation_category_ANY( "ANY" );
 static const trait_id trait_ARVORE_FOREST_MAPPING( "ARVORE_FOREST_MAPPING" );
 static const trait_id trait_BURROW( "BURROW" );
 static const trait_id trait_BURROWLARGE( "BURROWLARGE" );
+static const trait_id trait_CHAOTIC( "CHAOTIC" );
 static const trait_id trait_CHAOTIC_BAD( "CHAOTIC_BAD" );
 static const trait_id trait_ECHOLOCATION( "ECHOLOCATION" );
 static const trait_id trait_GASTROPOD_EXTREMITY2( "GASTROPOD_EXTREMITY2" );
@@ -1343,8 +1344,24 @@ void Character::mutate( const int &true_random_chance, bool use_vitamins )
             }
             if( mutate_towards( valid, cat, 2, use_vitamins ) ) {
                 add_msg_if_player( m_mixed, mutation_category_trait::get_category( cat ).mutagen_message() );
+                int sub_count = count_threshold_substitute_traits();
+                if( sub_count > 2 ) {
+                    int chance = sub_count - 2;
+                    if( !has_trait( trait_CHAOTIC ) && !has_trait( trait_CHAOTIC_BAD ) ) {
+                        if( rng( 1, 100 ) <= chance ) {
+                            mutate_towards( trait_CHAOTIC );
+                            add_msg_if_player( m_bad, _( "You will mutate uncontrollably from now on!" ) );
+                        } else if( has_trait( trait_CHAOTIC ) && !has_trait( trait_CHAOTIC_BAD ) ) {
+                            if( rng( 1, 100 ) <= chance ) {
+                                mutate_towards( trait_CHAOTIC_BAD );
+                                add_msg_if_player( m_bad, _( "Your genetics have become irreparably damaged!" ) );
+                            }
+                        }
+                    }
+                    return;
+                }
+                return;
             }
-            return;
         }
     } while( valid.empty() );
 }
@@ -1417,6 +1434,12 @@ void Character::mutate_category( const mutation_category_id &cat )
 bool Character::mutation_selector( const std::vector<trait_id> &prospective_traits,
                                    const mutation_category_id &cat, const bool &use_vitamins )
 {
+    if( has_trait( trait_CHAOTIC ) || has_trait( trait_CHAOTIC_BAD ) ) {
+        add_msg_if_player( m_bad,
+                           _( "Your genetic degeneration prevents you from selecting a mutation directly!" ) );
+        return false;
+    }
+
     // Setup menu
     uilist mmenu;
     mmenu.text =