Added utility function randSeedFloat

basically just `Phaser.math.RND.realInRange(0, 1)`

src/battle.ts

@@ -8,6 +8,7 @@ import {
   shiftCharCodes,
   randSeedItem,
   randInt,
+  randSeedFloat,
 } from "#app/utils/common";
 import Trainer, { TrainerVariant } from "./field/trainer";
 import type { GameMode } from "./game-mode";
@@ -150,7 +151,7 @@ export default class Battle {
   randSeedGaussForLevel(value: number): number {
     let rand = 0;
     for (let i = value; i > 0; i--) {
-      rand += Phaser.Math.RND.realInRange(0, 1);
+      rand += randSeedFloat();
     }
     return rand / value;
   }

src/data/abilities/ability.ts

@@ -1,5 +1,5 @@
 import { HitResult, MoveResult, PlayerPokemon } from "#app/field/pokemon";
-import { BooleanHolder, NumberHolder, toDmgValue, isNullOrUndefined, randSeedItem, randSeedInt, type Constructor } from "#app/utils/common";
+import { BooleanHolder, NumberHolder, toDmgValue, isNullOrUndefined, randSeedItem, randSeedInt, type Constructor, randSeedFloat } from "#app/utils/common";
 import { getPokemonNameWithAffix } from "#app/messages";
 import { BattlerTagLapseType, GroundedTag } from "#app/data/battler-tags";
 import { getNonVolatileStatusEffects, getStatusEffectDescriptor, getStatusEffectHealText } from "#app/data/status-effect";
@@ -4071,8 +4071,8 @@ export class PostTurnRestoreBerryAbAttr extends PostTurnAbAttr {
     }
 
     // Clamp procChance to [0, 1]. Skip if didn't proc (less than pass)
-    const pass = Phaser.Math.RND.realInRange(0, 1);
-    return Phaser.Math.Clamp(this.procChance(pokemon), 0, 1) >= pass;
+    const pass = randSeedFloat();
+    return Phaser.Math.Clamp(this.procChance(pokemon), 1, 0) >= pass;
   }
 
   override applyPostTurn(pokemon: Pokemon, passive: boolean, simulated: boolean, args: any[]): void {

src/data/moves/move.ts

@@ -29,7 +29,7 @@ import {
 } from "../status-effect";
 import { getTypeDamageMultiplier } from "../type";
 import { PokemonType } from "#enums/pokemon-type";
-import { BooleanHolder, NumberHolder, isNullOrUndefined, toDmgValue, randSeedItem, randSeedInt, getEnumValues, toReadableString, type Constructor } from "#app/utils/common";
+import { BooleanHolder, NumberHolder, isNullOrUndefined, toDmgValue, randSeedItem, randSeedInt, getEnumValues, toReadableString, type Constructor, randSeedFloat } from "#app/utils/common";
 import { WeatherType } from "#enums/weather-type";
 import type { ArenaTrapTag } from "../arena-tag";
 import { ArenaTagSide, WeakenMoveTypeTag } from "../arena-tag";
@@ -2549,8 +2549,8 @@ export class StealHeldItemChanceAttr extends MoveEffectAttr {
   }
 
   apply(user: Pokemon, target: Pokemon, move: Move, args: any[]): boolean {
-    const rand = Phaser.Math.RND.realInRange(0, 1);
-    if (rand >= this.chance) {
+    const rand = randSeedFloat();
+    if (rand > this.chance) {
       return false;
     }
     const heldItems = this.getTargetHeldItems(target).filter((i) => i.isTransferable);

src/data/pokemon-species.ts

@@ -8,7 +8,14 @@ import type { AnySound } from "#app/battle-scene";
 import { globalScene } from "#app/global-scene";
 import type { GameMode } from "#app/game-mode";
 import { DexAttr, type StarterMoveset } from "#app/system/game-data";
-import { isNullOrUndefined, capitalizeString, randSeedInt, randSeedGauss, randSeedItem } from "#app/utils/common";
+import {
+  isNullOrUndefined,
+  capitalizeString,
+  randSeedInt,
+  randSeedGauss,
+  randSeedItem,
+  randSeedFloat,
+} from "#app/utils/common";
 import { uncatchableSpecies } from "#app/data/balance/biomes";
 import { speciesEggMoves } from "#app/data/balance/egg-moves";
 import { GrowthRate } from "#app/data/exp";
@@ -749,7 +756,7 @@ export abstract class PokemonSpeciesForm {
     let paletteColors: Map<number, number> = new Map();
 
     const originalRandom = Math.random;
-    Math.random = () => Phaser.Math.RND.realInRange(0, 1);
+    Math.random = randSeedFloat;
 
     globalScene.executeWithSeedOffset(
       () => {
@@ -772,6 +779,7 @@ export default class PokemonSpecies extends PokemonSpeciesForm implements Locali
   readonly mythical: boolean;
   readonly species: string;
   readonly growthRate: GrowthRate;
+  /** The chance (as a decimal) for this Species to be male, or `null` for genderless species */
   readonly malePercent: number | null;
   readonly genderDiffs: boolean;
   readonly canChangeForm: boolean;
@@ -881,16 +889,14 @@ export default class PokemonSpecies extends PokemonSpeciesForm implements Locali
 
   /**
    * Pick and return a random {@linkcode Gender} for a {@linkcode Pokemon}.
-   * @param id The personality value of the pokemon being generated.
-   * @returns THe selected gender for this Pokemon, rolled based on its PID.
+   * @returns A randomly rolled gender based on this Species' {@linkcode malePercent}.
    */
-  generateGender(id: number): Gender {
+  generateGender(): Gender {
     if (isNullOrUndefined(this.malePercent)) {
       return Gender.GENDERLESS;
     }
 
-    const genderChance = (id % 256) * 0.390625;
-    if (genderChance < this.malePercent) {
+    if (randSeedFloat() <= this.malePercent) {
       return Gender.MALE;
     }
     return Gender.FEMALE;
@@ -1139,7 +1145,7 @@ export default class PokemonSpecies extends PokemonSpeciesForm implements Locali
       }
     }
 
-    if (noEvolutionChance === 1 || Phaser.Math.RND.realInRange(0, 1) < noEvolutionChance) {
+    if (noEvolutionChance === 1 || randSeedFloat() <= noEvolutionChance) {
       return this.speciesId;
     }
 

src/field/pokemon.ts

@@ -55,7 +55,7 @@ import {
   getStarterValueFriendshipCap,
   speciesStarterCosts,
 } from "#app/data/balance/starters";
-import { NumberHolder, randSeedInt, getIvsFromId, BooleanHolder, randSeedItem, isNullOrUndefined, getEnumValues, toDmgValue, fixedInt, rgbaToInt, rgbHexToRgba, rgbToHsv, deltaRgb, isBetween, type nil, type Constructor } from "#app/utils/common";
+import { NumberHolder, randSeedInt, getIvsFromId, BooleanHolder, randSeedItem, isNullOrUndefined, getEnumValues, toDmgValue, fixedInt, rgbaToInt, rgbHexToRgba, rgbToHsv, deltaRgb, isBetween, type nil, type Constructor, randSeedFloat } from "#app/utils/common";
 import type { TypeDamageMultiplier } from "#app/data/type";
 import { getTypeDamageMultiplier, getTypeRgb } from "#app/data/type";
 import { PokemonType } from "#enums/pokemon-type";
@@ -6046,7 +6046,7 @@ export default abstract class Pokemon extends Phaser.GameObjects.Container {
     let fusionPaletteColors: Map<number, number>;
 
     const originalRandom = Math.random;
-    Math.random = () => Phaser.Math.RND.realInRange(0, 1);
+    Math.random = randSeedFloat;
 
     globalScene.executeWithSeedOffset(
       () => {

src/modifier/modifier.ts

@@ -15,7 +15,7 @@ import { PokemonHealPhase } from "#app/phases/pokemon-heal-phase";
 import type { VoucherType } from "#app/system/voucher";
 import { Command } from "#app/ui/command-ui-handler";
 import { addTextObject, TextStyle } from "#app/ui/text";
-import { BooleanHolder, hslToHex, isNullOrUndefined, NumberHolder, toDmgValue } from "#app/utils/common";
+import { BooleanHolder, hslToHex, isNullOrUndefined, NumberHolder, randSeedFloat, toDmgValue } from "#app/utils/common";
 import { BattlerTagType } from "#enums/battler-tag-type";
 import { BerryType } from "#enums/berry-type";
 import type { Moves } from "#enums/moves";
@@ -3365,7 +3365,7 @@ export class ContactHeldItemTransferChanceModifier extends HeldItemTransferModif
   }
 
   getTransferredItemCount(): number {
-    return Phaser.Math.RND.realInRange(0, 1) < this.chance * this.getStackCount() ? 1 : 0;
+    return randSeedFloat() <= this.chance * this.getStackCount() ? 1 : 0;
   }
 
   getTransferMessage(pokemon: Pokemon, targetPokemon: Pokemon, item: ModifierType): string {
@@ -3643,7 +3643,7 @@ export class EnemyAttackStatusEffectChanceModifier extends EnemyPersistentModifi
    * @returns `true` if the {@linkcode Pokemon} was affected
    */
   override apply(enemyPokemon: Pokemon): boolean {
-    if (Phaser.Math.RND.realInRange(0, 1) < this.chance * this.getStackCount()) {
+    if (randSeedFloat() <= this.chance * this.getStackCount()) {
       return enemyPokemon.trySetStatus(this.effect, true);
     }
 
@@ -3683,16 +3683,16 @@ export class EnemyStatusEffectHealChanceModifier extends EnemyPersistentModifier
    * @returns `true` if the {@linkcode Pokemon} was healed
    */
   override apply(enemyPokemon: Pokemon): boolean {
-    if (enemyPokemon.status && Phaser.Math.RND.realInRange(0, 1) < this.chance * this.getStackCount()) {
-      globalScene.queueMessage(
-        getStatusEffectHealText(enemyPokemon.status.effect, getPokemonNameWithAffix(enemyPokemon)),
-      );
-      enemyPokemon.resetStatus();
-      enemyPokemon.updateInfo();
-      return true;
+    if (!enemyPokemon.status || randSeedFloat() > this.chance * this.getStackCount()) {
+      return false;
     }
 
-    return false;
+    globalScene.queueMessage(
+      getStatusEffectHealText(enemyPokemon.status.effect, getPokemonNameWithAffix(enemyPokemon)),
+    );
+    enemyPokemon.resetStatus();
+    enemyPokemon.updateInfo();
+    return true;
   }
 
   getMaxStackCount(): number {
@@ -3771,7 +3771,7 @@ export class EnemyFusionChanceModifier extends EnemyPersistentModifier {
    * @returns `true` if the {@linkcode EnemyPokemon} is a fusion
    */
   override apply(isFusion: BooleanHolder): boolean {
-    if (Phaser.Math.RND.realInRange(0, 1) >= this.chance * this.getStackCount()) {
+    if (randSeedFloat() > this.chance * this.getStackCount()) {
       return false;
     }
 

src/utils/common.ts

@@ -57,8 +57,8 @@ export function randSeedGauss(stdev: number, mean = 0): number {
   if (!stdev) {
     return 0;
   }
-  const u = 1 - Phaser.Math.RND.realInRange(0, 1);
-  const v = Phaser.Math.RND.realInRange(0, 1);
+  const u = 1 - randSeedFloat();
+  const v = randSeedFloat();
   const z = Math.sqrt(-2.0 * Math.log(u)) * Math.cos(2.0 * Math.PI * v);
   return z * stdev + mean;
 }
@@ -87,9 +87,9 @@ export function randInt(range: number, min = 0): number {
 }
 
 /**
- * Generates a random number using the global seed, or the current battle's seed if called via `Battle.randSeedInt`
- * @param range How large of a range of random numbers to choose from. If {@linkcode range} <= 1, returns {@linkcode min}
- * @param min The minimum integer to pick, default `0`
+ * Generate a random integer using the global seed, or the current battle's seed if called via `Battle.randSeedInt`
+ * @param range - How large of a range of random numbers to choose from. If {@linkcode range} <= 1, returns {@linkcode min}
+ * @param min - The minimum integer to pick, default `0`
  * @returns A random integer between {@linkcode min} and ({@linkcode min} + {@linkcode range} - 1)
  */
 export function randSeedInt(range: number, min = 0): number {
@@ -108,6 +108,14 @@ export function randIntRange(min: number, max: number): number {
   return randInt(max - min, min);
 }
 
+/**
+ * Generate and return a random real number between `0` and `1` using the global seed.
+ * @returns A random floating-point number between `0` and `1`
+ */
+export function randSeedFloat(): number {
+  return Phaser.Math.RND.frac();
+}
+
 export function randItem<T>(items: T[]): T {
   return items.length === 1 ? items[0] : items[randInt(items.length)];
 }
@@ -502,12 +510,19 @@ export function capitalizeString(str: string, sep: string, lowerFirstChar = true
   return null;
 }
 
-export function isNullOrUndefined(object: any): object is null | undefined {
-  return object === null || object === undefined;
+/**
+ * Report whether a given value is nullish (`null`/`undefined`).
+ * @param val - The value whose nullishness is being checked
+ * @returns `true` if `val` is either `null` or `undefined`
+ */
+export function isNullOrUndefined(val: any): val is null | undefined {
+  return val === null || val === undefined;
 }
 
 /**
- * Capitalizes the first letter of a string
+ * Capitalize the first letter of a string.
+ * @param str - The string whose first letter is being capitalized
+ * @return The original string with its first letter capitalized
  */
 export function capitalizeFirstLetter(str: string) {
   return str.charAt(0).toUpperCase() + str.slice(1);