Applying hediffs by Gene works

Source/Common/Defs/HediffIncreaseOnSexExtension.cs

@@ -0,0 +1,23 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Verse;
+
+namespace RJW_Genes
+{
+    public class HediffIncreaseOnSexExtension: DefModExtension
+    {
+        public HediffDef hediffDef;
+        public float severityIncrease;
+        public float applicationChance;
+
+        public bool canCreateHediff;
+
+        public bool applicableForWomen;
+        public bool applicableForMen;
+        public bool requiresPenetrativeSex;
+    }
+
+}

Source/Common/patches/Patch_HediffIncreaseOnSex.cs

@@ -0,0 +1,80 @@
+using HarmonyLib;
+using rjw;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Verse;
+
+namespace RJW_Genes
+{
+
+    /// <summary>
+    /// This patch "only" applies the hediff increase on sex. 
+    /// It checks for the hediff, creates it if necessary and applicable, 
+    /// and increases it based on the severity, chance and genders specified in the Extension. 
+    /// 
+    /// Some hediffs want follow up logic, e.g. the Feminization Gene, 
+    /// which is handled in an extra patch (that requires the hediff to be present already). 
+    /// </summary>
+    [HarmonyPatch(typeof(SexUtility), "Aftersex")]
+    public class Patch_HediffIncreaseOnSex
+    {
+
+        public static void Postfix(SexProps props)
+        {
+            if (props == null || props.pawn == null || props.partner == null || props.partner.IsAnimal() || props.pawn.IsAnimal())
+            {
+                return;
+            }
+
+            Pawn pawn = props.pawn;
+            Pawn partner = props.partner;
+
+            if (pawn.genes == null || partner.genes == null) return;
+
+            TryApplyHediffsOfSex(pawn, partner, props);
+            TryApplyHediffsOfSex(partner, pawn, props);
+        }
+
+        /// <summary>
+        /// Checks for every gene in a pawn if it applies a hediff or the severity of an existing hediff in a sexual partner. 
+        /// If the checks pass, the hediff is added or changed accordingly. 
+        /// </summary>
+        /// <param name="pawn">Pawn that holds (one or many) genes that might apply a hediff change</param>
+        /// <param name="partner">Pawn that will receive or alter any hediffs, if applicable</param>
+        /// <param name="props">The Sexprops, used for checking if sex is penetrative</param>
+        static void TryApplyHediffsOfSex(Pawn pawn, Pawn partner, SexProps props)
+        {
+            var random = new Random();
+
+            foreach (Gene gene in pawn.genes.GenesListForReading)
+            {
+                HediffIncreaseOnSexExtension ext = gene.def.GetModExtension<HediffIncreaseOnSexExtension>();
+                if (ext == null) continue;
+
+                if (DiseaseHelper.IsImmuneAgainstGeneticDisease(partner, gene.def)) continue;
+                if (ext.requiresPenetrativeSex && DiseaseHelper.IsPenetrativeSex(props)) continue;
+                if (!ext.applicableForMen && partner.gender == Gender.Male) continue;
+                if (!ext.applicableForWomen && partner.gender == Gender.Female) continue;
+                if (random.NextDouble() >= ext.applicationChance) continue;
+
+                Hediff hediff = partner.health.hediffSet.GetFirstHediffOfDef(ext.hediffDef);
+                if (hediff == null)
+                {
+                    if (!ext.canCreateHediff) continue;
+                    hediff = partner.health.GetOrAddHediff(ext.hediffDef);
+                    hediff.Severity = 0.01f;
+                    ModLog.Debug($"{partner} got hediff {hediff.def.defName} from Patch_HediffIncreaseOnSex ({gene.def.defName}) upon sex with {pawn}");
+                }
+                float initial_severity = hediff.Severity;
+                ModLog.Debug($"{partner}s hediff {hediff.def.defName} was changed by Patch_HediffIncreaseOnSex ({gene.def.defName}) upon sex with {pawn} [from {initial_severity} to {initial_severity + ext.severityIncrease}]");
+                hediff.Severity += ext.severityIncrease;
+
+                // DevNote: I also want to have "negative" hediff changes here, but I think its not necessary. Once the severity reaches 0, or below, the hediff should remove itself. 
+            }
+        }
+
+    }
+}

Source/Rjw-Genes.csproj

@@ -58,6 +58,7 @@
     <Compile Include="Animal_Inheritance\Defs\BestialityGeneInheritanceDef.cs" />
     <Compile Include="Common\Defs\ChanceExtension.cs" />
     <Compile Include="Common\Defs\DistanceExtension.cs" />
+    <Compile Include="Common\Defs\HediffIncreaseOnSexExtension.cs" />
     <Compile Include="Common\Defs\ModExtensionHelper.cs" />
     <Compile Include="Common\Defs\MultiplierExtension.cs" />
     <Compile Include="Common\Defs\TickBasedChanceExtension.cs" />
@@ -68,6 +69,7 @@
     <Compile Include="Common\ModLog.cs" />
     <Compile Include="Common\Defs\TickIntervalExtension.cs" />
     <Compile Include="Common\Patches\PatchImplants.cs" />
+    <Compile Include="Common\Patches\Patch_HediffIncreaseOnSex.cs" />
     <Compile Include="Common\Patches\Patch_ParentRelationUtility_GetParents.cs" />
     <Compile Include="Genes\Breeding\Abilities\CompAbilityEffect_MatingCall.cs" />
     <Compile Include="Genes\Breeding\Abilities\CompAbilityEffect_PheromoneSpit.cs" />