Let about a third of penises precum during sex

1.4/source/RJW_Menstruation/RJW_Menstruation/HediffComps/HediffComp_Menstruation.cs

@@ -737,11 +737,11 @@ namespace RJW_Menstruation
         /// <param name="pawn"></param>
         /// <param name="volume"></param>
         /// <param name="fertility"></param>
-        /// <param name="filthdef"></param>
-        public void CumIn(Pawn pawn, float volume, float fertility = 1.0f, ThingDef filthdef = null)
+        /// <param name="precum"></param>
+        public void CumIn(Pawn pawn, float volume, float fertility = 1.0f, bool precum = false)
         {
             if (volume <= 0) return;
-            if (fertility > 0 && IsDangerDay && pawn.relations.GetPregnancyApproachForPartner(Pawn) == PregnancyApproach.AvoidPregnancy)
+            if (!precum && fertility > 0 && IsDangerDay && pawn.relations.GetPregnancyApproachForPartner(Pawn) == PregnancyApproach.AvoidPregnancy)
             {
                 float successChance = pulloutSuccessRate;
                 if (pawn.Has(Quirk.ImpregnationFetish)) successChance *= fetishPulloutSuccessModifier;
@@ -759,12 +759,12 @@ namespace RJW_Menstruation
                     {
                         if (cum.pawn.Equals(pawn))
                         {
-                            cum.MergeWithCum(volume, fertility, filthdef);
+                            cum.MergeWithCum(volume, fertility);
                             merged = true;
                         }
                         cum.DismishForce(cumoutrate);
                     }
-                if (!merged) cums.Add(new Cum(pawn, volume * (1 - cumoutrate), fertility, filthdef));
+                if (!merged) cums.Add(new Cum(pawn, volume * (1 - cumoutrate), fertility));
             }
             else
             {
@@ -774,18 +774,21 @@ namespace RJW_Menstruation
                     {
                         if (cum.pawn.Equals(pawn))
                         {
-                            cum.MergeWithCum(volume, fertility, filthdef);
+                            cum.MergeWithCum(volume, fertility);
                             merged = true;
                         }
                     }
-                if (!merged) cums.Add(new Cum(pawn, volume, fertility, filthdef));
+                if (!merged) cums.Add(new Cum(pawn, volume, fertility));
             }
             cumd = TotalCumPercent - cumd;
 
+            if (!precum)
+            {
                 Pawn.records.AddTo(VariousDefOf.AmountofCreampied, volume);
                 AfterCumIn(pawn);
                 AfterFluidIn(cumd);
             }
+        }
 
         /// <summary>
         /// Inject pawn's fluid into womb

1.4/source/RJW_Menstruation/RJW_Menstruation/Patch/RJW_Patch.cs

@@ -70,7 +70,7 @@ namespace RJW_Menstruation
         /// </summary>
         /// <param name="props"></param>
         /// <returns>Interaction can result in pregnancy</returns>
-        private static bool InteractionCanCausePregnancy(SexProps props)
+        public static bool InteractionCanCausePregnancy(SexProps props)
         {
             InteractionWithExtension interaction = rjw.Modules.Interactions.Helpers.InteractionHelper.GetWithExtension(props.dictionaryKey);
 
@@ -331,6 +331,34 @@ namespace RJW_Menstruation
         }
     }
 
+    [HarmonyPatch(typeof(JobDriver_Sex), nameof(JobDriver_Sex.SexTick))]
+    public static class SexTick_Patch
+    {
+        private const float fertilePrecummersPercentage = 0.33f;
+        private const float precumRatio = 0.1f; // Relative to ejaculation volume
+        private const float precumFertility = 0.5f;
+        private const float expectedDurationTicks = 2000f * (0.9f - 0.5f) / 2;
+
+        public static void Postfix(JobDriver_Sex __instance, Pawn pawn, Thing target)
+        {
+            if (!pawn.IsHashIntervalTick(__instance.ticks_between_thrusts)) return;
+            xxx.rjwSextype sextype = __instance.Sexprops.sexType;
+            if (!(target is Pawn partner) || pawn == partner) return;
+            if (sextype != xxx.rjwSextype.Vaginal && sextype != xxx.rjwSextype.DoublePenetration) return;
+            if (__instance.Sexprops.usedCondom) return;
+            if (!Impregnate_Patch.InteractionCanCausePregnancy(__instance.Sexprops)) return;
+
+            // Archotech penises have more control. Or something.
+            CompHediffBodyPart penisComp = pawn.GetGenitalsList()?.Find(genital => (genital as Hediff_PartBaseNatural)?.def.defName.ToLower().Contains("penis") ?? false)?.TryGetComp<CompHediffBodyPart>();
+            if (penisComp == null || Rand.ChanceSeeded(1.0f - fertilePrecummersPercentage, Gen.HashOffset(penisComp.parent.loadID))) return;
+            HediffComp_Menstruation vaginaComp = partner.GetRandomMenstruationComp();
+            if (vaginaComp == null) return;
+
+            float precumAmount = pawn.GetCumVolume(penisComp) * precumRatio * __instance.ticks_between_thrusts / expectedDurationTicks;
+            vaginaComp.CumIn(pawn, precumAmount, pawn.SterileGenes() ? 0.0f : precumFertility * pawn.health.capacities.GetLevel(xxx.reproduction), true);
+        }
+    }
+
     [HarmonyPatch(typeof(CompHediffBodyPart), nameof(CompHediffBodyPart.updatesize))]
     public static class Updatesize_Patch
     {

changelogs.txt

@@ -2,6 +2,7 @@ Version 1.0.8.5
  - Added biosculpter recipe to restore 1 year's worth of eggs.
  - Vaginal sex with the "avoid pregnancy" relation will (usually) pull out prevent cum from entering the womb if there's a risk of pregnancy.
  - Impregnation fetishists are significantly less likely to pull out.
+ - Some males will release small amounts of semen into a womb during vaginal sex before their actual ejaculation.
  - Babies born from multiple pregnancy will properly produce the prompt to name them.
 
 Version 1.0.8.4