From b35342fa41d29524491106001e9361b145242377 Mon Sep 17 00:00:00 2001
From: Anton Simakov <67688115+GuardianDll@users.noreply.github.com>
Date: Sat, 14 Sep 2024 16:13:16 +0200
Subject: [PATCH] add chance field for jmapgen_field (#76380)

* add chance field for jmapgen_field

* document field

* astyle
---
 doc/MAPGEN.md  |  1 +
 src/mapgen.cpp | 12 +++++++++---
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/doc/MAPGEN.md b/doc/MAPGEN.md
index 25f9739efbb94..faf79da78e8e2 100644
--- a/doc/MAPGEN.md
+++ b/doc/MAPGEN.md
@@ -856,6 +856,7 @@ Example:
 | intensity | (optional, integer, array ) how concentrated the field is, from 1 to 3 or more.  Arrays are randomized.  See `data/json/field_type.json`
 | age       | (optional, integer) field age. Defaults to 0.
 | remove    | (optional, bool) If true the given field will be removed rather than added. Defaults to false.
+| chance    | (optional, integer) chance to spawn field; default `100` as 100%
 
 
 ### Place NPCs with "npcs"
diff --git a/src/mapgen.cpp b/src/mapgen.cpp
index d7883c277c201..41a3e02dd8de9 100644
--- a/src/mapgen.cpp
+++ b/src/mapgen.cpp
@@ -1947,10 +1947,12 @@ class jmapgen_field : public jmapgen_piece
         mapgen_value<field_type_id> ftype;
         std::vector<int> intensities;
         time_duration age;
+        int chance;
         bool remove;
         jmapgen_field( const JsonObject &jsi, const std::string_view/*context*/ ) :
             ftype( jsi.get_member( "field" ) )
             , age( time_duration::from_turns( jsi.get_int( "age", 0 ) ) )
+            , chance( jsi.get_int( "chance", 100 ) )
             , remove( jsi.get_bool( "remove", false ) ) {
             if( jsi.has_array( "intensity" ) ) {
                 for( JsonValue jv : jsi.get_array( "intensity" ) ) {
@@ -1968,10 +1970,14 @@ class jmapgen_field : public jmapgen_piece
                 return;
             }
             if( remove ) {
-                dat.m.remove_field( tripoint_bub_ms( x.get(), y.get(), dat.zlevel() + z.get() ), chosen_id );
+                if( x_in_y( chance, 100 ) ) {
+                    dat.m.remove_field( tripoint_bub_ms( x.get(), y.get(), dat.zlevel() + z.get() ), chosen_id );
+                }
             } else {
-                dat.m.add_field( tripoint_bub_ms( x.get(), y.get(), dat.zlevel() + z.get() ), chosen_id,
-                                 random_entry( intensities ), age );
+                if( x_in_y( chance, 100 ) ) {
+                    dat.m.add_field( tripoint_bub_ms( x.get(), y.get(), dat.zlevel() + z.get() ), chosen_id,
+                                     random_entry( intensities ), age );
+                }
             }
         }