Add modifier transfer functionality

src/battle-phases.ts

@@ -16,7 +16,7 @@ import { EvolutionPhase } from "./evolution-phase";
 import { BattlePhase } from "./battle-phase";
 import { BattleStat, getBattleStatLevelChangeDescription, getBattleStatName } from "./data/battle-stat";
 import { Biome, biomeLinks } from "./data/biome";
-import { ModifierTypeOption, PokemonModifierType, PokemonMoveModifierType, getPlayerModifierTypeOptionsForWave, regenerateModifierPoolThresholds } from "./modifier/modifier-type";
+import { ModifierTypeOption, PokemonModifierType, PokemonMoveModifierType, getEnemyModifierTypesForWave, getPlayerModifierTypeOptionsForWave, regenerateModifierPoolThresholds } from "./modifier/modifier-type";
 import SoundFade from "phaser3-rex-plugins/plugins/soundfade";
 import { BattleTagLapseType, BattleTagType, HideSpriteTag as HiddenTag } from "./data/battle-tag";
 import { getPokemonMessage } from "./messages";
@@ -1838,6 +1838,37 @@ export class SelectModifierPhase extends BattlePhase {
         this.scene.ui.setMode(Mode.MESSAGE);
         super.end();
         return;
+      } else if (cursor >= typeOptions.length) {
+        this.scene.ui.setModeWithoutClear(Mode.PARTY, PartyUiMode.MODIFIER_TRANSFER, (fromSlotIndex: integer, itemIndex: integer, toSlotIndex: integer) => {
+          if (toSlotIndex !== undefined && fromSlotIndex < 6 && toSlotIndex < 6 && fromSlotIndex !== toSlotIndex && itemIndex > -1) {
+            this.scene.ui.setMode(Mode.MODIFIER_SELECT);
+            const itemModifiers = this.scene.findModifiers(m => m instanceof PokemonHeldItemModifier
+                && (m as PokemonHeldItemModifier).pokemonId === party[fromSlotIndex].id) as PokemonHeldItemModifier[];
+            const itemModifier = itemModifiers[itemIndex];
+            const newItemModifier = itemModifier.clone() as PokemonHeldItemModifier;
+            newItemModifier.pokemonId = party[toSlotIndex].id;
+            const matchingModifier = party[toSlotIndex].scene.findModifier(m => m instanceof PokemonHeldItemModifier
+                && (m as PokemonHeldItemModifier).matchType(itemModifier)) as PokemonHeldItemModifier;
+            let removeOld = true;
+            if (matchingModifier) {
+              const newStackCount = matchingModifier.stackCount + itemModifier.stackCount;
+              const maxStackCount = matchingModifier.getMaxStackCount();
+              if (newStackCount > maxStackCount) {
+                itemModifier.stackCount = newStackCount - maxStackCount;
+                newItemModifier.stackCount = maxStackCount;
+                removeOld = !itemModifier.stackCount;
+              }
+            }
+            if (!removeOld || this.scene.removeModifier(itemModifier)) {
+              this.scene.addModifier(newItemModifier, true).then(() => super.end());
+              this.scene.ui.clearText();
+              this.scene.ui.setMode(Mode.MESSAGE);
+              return;
+            }
+          }
+          this.scene.ui.setMode(Mode.MODIFIER_SELECT, typeOptions, modifierSelectCallback);
+        }, PartyUiHandler.FilterItemMaxStacks);
+        return;
       }
 
       const modifierType = typeOptions[cursor].type;

src/battle-scene.ts

@@ -21,6 +21,7 @@ import { Moves } from './data/move';
 import { getDefaultModifierTypeForTier, getEnemyModifierTypesForWave } from './modifier/modifier-type';
 
 const enableAuto = true;
+const quickStart = false;
 export const startingLevel = 5;
 export const startingWave = 1;
 export const startingBiome = Biome.PLAINS;
@@ -45,7 +46,7 @@ export enum Button {
 export default class BattleScene extends Phaser.Scene {
 	public auto: boolean;
 	public gameSpeed: integer = 1;
-	public quickStart: boolean;
+	public quickStart: boolean = quickStart;
 
 	public gameData: GameData;
 
@@ -160,9 +161,13 @@ export default class BattleScene extends Phaser.Scene {
 		this.loadImage('party_message', 'ui');
 		this.loadImage('party_message_large', 'ui');
 		this.loadImage('party_message_options', 'ui');
+		this.loadImage('party_message_options_wide', 'ui');
 		this.loadImage('party_options_top', 'ui');
 		this.loadImage('party_options_center', 'ui');
 		this.loadImage('party_options_bottom', 'ui');
+		this.loadImage('party_options_wide_top', 'ui');
+		this.loadImage('party_options_wide_center', 'ui');
+		this.loadImage('party_options_wide_bottom', 'ui');
 		this.loadAtlas('party_cancel', 'ui');
 
 		this.loadImage('summary_bg', 'ui');
@@ -174,8 +179,8 @@ export default class BattleScene extends Phaser.Scene {
 		this.loadImage('summary_moves_overlay_pp', 'ui');
 		this.loadAtlas('summary_moves_cursor', 'ui');
 
-		this.loadImage('biome_select_window_2', 'ui');
+		for (let o = 1; o <= 3; o++)
-		this.loadImage('biome_select_window_3', 'ui');
+			this.loadImage(`option_select_window_${o}`, 'ui');
 
 		this.loadImage('starter_select_bg', 'ui');
 		this.loadImage('starter_select_message', 'ui');

src/modifier/modifier.ts

@@ -69,16 +69,16 @@ export abstract class PersistentModifier extends Modifier {
   public stackCount: integer;
   public virtualStackCount: integer;
 
-  constructor(type: ModifierType) {
+  constructor(type: ModifierType, stackCount: integer) {
     super(type);
-    this.stackCount = 1;
+    this.stackCount = stackCount === undefined ? 1 : stackCount;
     this.virtualStackCount = 0;
   }
 
   add(modifiers: PersistentModifier[], virtual: boolean): boolean {
     for (let modifier of modifiers) {
       if (this.match(modifier))
-        return modifier.incrementStack(virtual);
+        return modifier.incrementStack(modifier.stackCount, virtual);
     }
 
     if (virtual) {
@@ -91,12 +91,12 @@ export abstract class PersistentModifier extends Modifier {
 
   abstract clone(): PersistentModifier;
 
-  incrementStack(virtual: boolean): boolean {
+  incrementStack(amount: integer, virtual: boolean): boolean {
-    if (this.getStackCount() < this.getMaxStackCount()) {
+    if (this.getStackCount() + amount <= this.getMaxStackCount()) {
       if (!virtual)
-        this.stackCount++;
+        this.stackCount += amount;
       else
-        this.virtualStackCount++;
+        this.virtualStackCount += amount;
       return true;
     }
 
@@ -193,15 +193,15 @@ export class TempBattleStatBoosterModifier extends PersistentModifier {
   private tempBattleStat: TempBattleStat;
   private battlesLeft: integer;
 
-  constructor(type: ModifierTypes.TempBattleStatBoosterModifierType, tempBattleStat: TempBattleStat) {
+  constructor(type: ModifierTypes.TempBattleStatBoosterModifierType, tempBattleStat: TempBattleStat, stackCount?: integer) {
-    super(type);
+    super(type, stackCount);
 
     this.tempBattleStat = tempBattleStat;
     this.battlesLeft = 5;
   }
 
   clone(): TempBattleStatBoosterModifier {
-    return new TempBattleStatBoosterModifier(this.type as ModifierTypes.TempBattleStatBoosterModifierType, this.tempBattleStat);
+    return new TempBattleStatBoosterModifier(this.type as ModifierTypes.TempBattleStatBoosterModifierType, this.tempBattleStat, this.stackCount);
   }
 
   apply(args: any[]): boolean {
@@ -236,12 +236,18 @@ export class TempBattleStatBoosterModifier extends PersistentModifier {
 export abstract class PokemonHeldItemModifier extends PersistentModifier {
   public pokemonId: integer;
 
-  constructor(type: ModifierType, pokemonId: integer) {
+  constructor(type: ModifierType, pokemonId: integer, stackCount: integer) {
-    super(type);
+    super(type, stackCount);
 
     this.pokemonId = pokemonId;
   }
 
+  abstract matchType(_modifier: Modifier): boolean;
+
+  match(modifier: Modifier) {
+    return this.matchType(modifier) && (modifier as PokemonHeldItemModifier).pokemonId === this.pokemonId;
+  }
+
   shouldApply(args: any[]): boolean {
     return super.shouldApply(args) && args.length && args[0] instanceof Pokemon && (this.pokemonId === -1 || (args[0] as Pokemon).id === this.pokemonId);
   }
@@ -282,21 +288,19 @@ export abstract class PokemonHeldItemModifier extends PersistentModifier {
 export class PokemonBaseStatModifier extends PokemonHeldItemModifier {
   protected stat: Stat;
 
-  constructor(type: ModifierTypes.PokemonBaseStatBoosterModifierType, pokemonId: integer, stat: Stat) {
+  constructor(type: ModifierTypes.PokemonBaseStatBoosterModifierType, pokemonId: integer, stat: Stat, stackCount?: integer) {
-    super(type, pokemonId);
+    super(type, pokemonId, stackCount);
     this.stat = stat;
   }
 
-  match(modifier: Modifier): boolean {
+  matchType(modifier: Modifier): boolean {
-    if (modifier instanceof PokemonBaseStatModifier) {
+    if (modifier instanceof PokemonBaseStatModifier)
-      const pokemonStatModifier = modifier as PokemonBaseStatModifier;
+      return (modifier as PokemonBaseStatModifier).stat === this.stat;
-      return pokemonStatModifier.pokemonId === this.pokemonId && pokemonStatModifier.stat === this.stat;
-    }
     return false;
   }
 
   clone(): PersistentModifier {
-    return new PokemonBaseStatModifier(this.type as ModifierTypes.PokemonBaseStatBoosterModifierType, this.pokemonId, this.stat);
+    return new PokemonBaseStatModifier(this.type as ModifierTypes.PokemonBaseStatBoosterModifierType, this.pokemonId, this.stat, this.stackCount);
   }
 
   shouldApply(args: any[]): boolean {
@@ -314,19 +318,22 @@ export class AttackTypeBoosterModifier extends PokemonHeldItemModifier {
   private moveType: Type;
   private boostMultiplier: number;
 
-  constructor(type: ModifierType, pokemonId: integer, moveType: Type, boostPercent: integer) {
+  constructor(type: ModifierType, pokemonId: integer, moveType: Type, boostPercent: integer, stackCount?: integer) {
-    super(type, pokemonId);
+    super(type, pokemonId, stackCount);
 
     this.moveType = moveType;
     this.boostMultiplier = boostPercent * 0.01;
   }
 
-  match(modifier: Modifier) {
+  matchType(modifier: Modifier) {
-    return modifier instanceof AttackTypeBoosterModifier;
+    if (modifier instanceof AttackTypeBoosterModifier) {
+      const attackTypeBoosterModifier = modifier as AttackTypeBoosterModifier;
+      return attackTypeBoosterModifier.moveType === this.moveType && attackTypeBoosterModifier.boostMultiplier === this.boostMultiplier;
+    }
   }
 
   clone() {
-    return new AttackTypeBoosterModifier(this.type, this.pokemonId, this.moveType, this.boostMultiplier * 100);
+    return new AttackTypeBoosterModifier(this.type, this.pokemonId, this.moveType, this.boostMultiplier * 100, this.stackCount);
   }
 
   shouldApply(args: any[]): boolean {
@@ -341,16 +348,16 @@ export class AttackTypeBoosterModifier extends PokemonHeldItemModifier {
 }
 
 export class TurnHealModifier extends PokemonHeldItemModifier {
-  constructor(type: ModifierType, pokemonId: integer) {
+  constructor(type: ModifierType, pokemonId: integer, stackCount?: integer) {
-    super(type, pokemonId);
+    super(type, pokemonId, stackCount);
   }
 
-  match(modifier: Modifier) {
+  matchType(modifier: Modifier) {
     return modifier instanceof TurnHealModifier;
   }
 
   clone() {
-    return new TurnHealModifier(this.type, this.pokemonId);
+    return new TurnHealModifier(this.type, this.pokemonId, this.stackCount);
   }
 
   apply(args: any[]): boolean {
@@ -370,16 +377,16 @@ export class TurnHealModifier extends PokemonHeldItemModifier {
 }
 
 export class HitHealModifier extends PokemonHeldItemModifier {
-  constructor(type: ModifierType, pokemonId: integer) {
+  constructor(type: ModifierType, pokemonId: integer, stackCount?: integer) {
-    super(type, pokemonId);
+    super(type, pokemonId, stackCount);
   }
 
-  match(modifier: Modifier) {
+  matchType(modifier: Modifier) {
     return modifier instanceof HitHealModifier;
   }
 
   clone() {
-    return new HitHealModifier(this.type, this.pokemonId);
+    return new HitHealModifier(this.type, this.pokemonId, this.stackCount);
   }
 
   apply(args: any[]): boolean {
@@ -402,19 +409,19 @@ export class BerryModifier extends PokemonHeldItemModifier {
   public berryType: BerryType;
   public consumed: boolean;
 
-  constructor(type: ModifierType, pokemonId: integer, berryType: BerryType) {
+  constructor(type: ModifierType, pokemonId: integer, berryType: BerryType, stackCount?: integer) {
-    super(type, pokemonId);
+    super(type, pokemonId, stackCount);
 
     this.berryType = berryType;
     this.consumed = false;
   }
 
-  match(modifier: Modifier) {
+  matchType(modifier: Modifier) {
-    return modifier instanceof BerryModifier && (modifier as BerryModifier).berryType === this.berryType && modifier.pokemonId === this.pokemonId;
+    return modifier instanceof BerryModifier && (modifier as BerryModifier).berryType === this.berryType;
   }
 
   clone() {
-    return new BerryModifier(this.type, this.pokemonId, this.berryType);
+    return new BerryModifier(this.type, this.pokemonId, this.berryType, this.stackCount);
   }
 
   shouldApply(args: any[]): boolean {
@@ -436,8 +443,8 @@ export class BerryModifier extends PokemonHeldItemModifier {
 }
 
 export class PreserveBerryModifier extends PersistentModifier {
-  constructor(type: ModifierType) {
+  constructor(type: ModifierType, stackCount?: integer) {
-    super(type);
+    super(type, stackCount);
   }
 
   match(modifier: Modifier) {
@@ -445,7 +452,7 @@ export class PreserveBerryModifier extends PersistentModifier {
   }
 
   clone() {
-    return new PreserveBerryModifier(this.type);
+    return new PreserveBerryModifier(this.type, this.stackCount);
   }
 
   shouldApply(args: any[]): boolean {
@@ -628,8 +635,8 @@ export class EvolutionItemModifier extends ConsumablePokemonModifier {
 }
 
 export class PartyShareModifier extends PersistentModifier {
-  constructor(type: ModifierType) {
+  constructor(type: ModifierType, stackCount?: integer) {
-    super(type);
+    super(type, stackCount);
   }
 
   match(modifier: Modifier) {
@@ -637,7 +644,7 @@ export class PartyShareModifier extends PersistentModifier {
   }
 
   clone(): PartyShareModifier {
-    return new PartyShareModifier(this.type);
+    return new PartyShareModifier(this.type, this.stackCount);
   }
 
   shouldApply(args: any[]): boolean {
@@ -675,8 +682,8 @@ export class PartyShareModifier extends PersistentModifier {
 export class HealingBoosterModifier extends PersistentModifier {
   private multiplier: number;
 
-  constructor(type: ModifierType, multiplier: number) {
+  constructor(type: ModifierType, multiplier: number, stackCount?: integer) {
-    super(type);
+    super(type, stackCount);
 
     this.multiplier = multiplier;
   }
@@ -686,7 +693,7 @@ export class HealingBoosterModifier extends PersistentModifier {
   }
 
   clone(): HealingBoosterModifier {
-    return new HealingBoosterModifier(this.type, this.multiplier);
+    return new HealingBoosterModifier(this.type, this.multiplier, this.stackCount);
   }
 
   apply(args: any[]): boolean {
@@ -702,8 +709,8 @@ export class HealingBoosterModifier extends PersistentModifier {
 export class ExpBoosterModifier extends PersistentModifier {
   private boostMultiplier: integer;
 
-  constructor(type: ModifierType, boostPercent: integer) {
+  constructor(type: ModifierType, boostPercent: integer, stackCount?: integer) {
-    super(type);
+    super(type, stackCount);
 
     this.boostMultiplier = boostPercent * 0.01;
   }
@@ -717,7 +724,7 @@ export class ExpBoosterModifier extends PersistentModifier {
   }
 
   clone(): ExpBoosterModifier {
-    return new ExpBoosterModifier(this.type, this.boostMultiplier * 100);
+    return new ExpBoosterModifier(this.type, this.boostMultiplier * 100, this.stackCount);
   }
 
   apply(args: any[]): boolean {
@@ -730,21 +737,21 @@ export class ExpBoosterModifier extends PersistentModifier {
 export class PokemonExpBoosterModifier extends PokemonHeldItemModifier {
   private boostMultiplier: integer;
 
-  constructor(type: ModifierTypes.PokemonExpBoosterModifierType, pokemonId: integer, boostPercent: integer) {
+  constructor(type: ModifierTypes.PokemonExpBoosterModifierType, pokemonId: integer, boostPercent: integer, stackCount?: integer) {
-    super(type, pokemonId);
+    super(type, pokemonId, stackCount);
     this.boostMultiplier = boostPercent * 0.01;
   }
 
-  match(modifier: Modifier): boolean {
+  matchType(modifier: Modifier): boolean {
     if (modifier instanceof PokemonExpBoosterModifier) {
       const pokemonExpModifier = modifier as PokemonExpBoosterModifier;
-      return pokemonExpModifier.pokemonId === this.pokemonId && pokemonExpModifier.boostMultiplier === this.boostMultiplier;
+      return pokemonExpModifier.boostMultiplier === this.boostMultiplier;
     }
     return false;
   }
 
   clone(): PersistentModifier {
-    return new PokemonExpBoosterModifier(this.type as ModifierTypes.PokemonExpBoosterModifierType, this.pokemonId, this.boostMultiplier * 100);
+    return new PokemonExpBoosterModifier(this.type as ModifierTypes.PokemonExpBoosterModifierType, this.pokemonId, this.boostMultiplier * 100, this.stackCount);
   }
 
   shouldApply(args: any[]): boolean {
@@ -759,8 +766,8 @@ export class PokemonExpBoosterModifier extends PokemonHeldItemModifier {
 }
 
 export class ExpShareModifier extends PersistentModifier {
-  constructor(type: ModifierType) {
+  constructor(type: ModifierType, stackCount?: integer) {
-    super(type);
+    super(type, stackCount);
   }
 
   match(modifier: Modifier): boolean {
@@ -772,7 +779,7 @@ export class ExpShareModifier extends PersistentModifier {
   }
 
   clone(): ExpShareModifier {
-    return new ExpShareModifier(this.type);
+    return new ExpShareModifier(this.type, this.stackCount);
   }
 
   getMaxStackCount(): integer {
@@ -781,8 +788,8 @@ export class ExpShareModifier extends PersistentModifier {
 }
 
 export class ExpBalanceModifier extends PersistentModifier {
-  constructor(type: ModifierType) {
+  constructor(type: ModifierType, stackCount?: integer) {
-    super(type);
+    super(type, stackCount);
   }
 
   match(modifier: Modifier): boolean {
@@ -794,7 +801,7 @@ export class ExpBalanceModifier extends PersistentModifier {
   }
 
   clone(): ExpBalanceModifier {
-    return new ExpBalanceModifier(this.type);
+    return new ExpBalanceModifier(this.type, this.stackCount);
   }
 
   getMaxStackCount(): integer {
@@ -803,8 +810,8 @@ export class ExpBalanceModifier extends PersistentModifier {
 }
 
 export class ShinyRateBoosterModifier extends PersistentModifier {
-  constructor(type: ModifierType) {
+  constructor(type: ModifierType, stackCount?: integer) {
-    super(type);
+    super(type, stackCount);
   }
 
   match(modifier: Modifier): boolean {
@@ -812,7 +819,7 @@ export class ShinyRateBoosterModifier extends PersistentModifier {
   }
 
   clone(): ShinyRateBoosterModifier {
-    return new ShinyRateBoosterModifier(this.type);
+    return new ShinyRateBoosterModifier(this.type, this.stackCount);
   }
 
   apply(args: any[]): boolean {
@@ -827,8 +834,8 @@ export class ShinyRateBoosterModifier extends PersistentModifier {
 }
 
 export class ExtraModifierModifier extends PersistentModifier {
-  constructor(type: ModifierType) {
+  constructor(type: ModifierType, stackCount?: integer) {
-    super(type);
+    super(type, stackCount);
   }
 
   match(modifier: Modifier): boolean {
@@ -836,7 +843,7 @@ export class ExtraModifierModifier extends PersistentModifier {
   }
 
   clone(): ExtraModifierModifier {
-    return new ExtraModifierModifier(this.type);
+    return new ExtraModifierModifier(this.type, this.stackCount);
   }
 
   apply(args: any[]): boolean {

src/ui/biome-select-ui-handler.ts

@@ -25,7 +25,7 @@ export default class BiomeSelectUiHandler extends UiHandler {
     this.biomeSelectContainer.setVisible(false);
     ui.add(this.biomeSelectContainer);
 
-    this.biomeSelectBg = this.scene.add.image(0, 0, 'biome_select_window_2');
+    this.biomeSelectBg = this.scene.add.image(0, 0, 'option_select_window_2');
     this.biomeSelectBg.setOrigin(0, 1);
     this.biomeSelectContainer.add(this.biomeSelectBg);
 
@@ -42,7 +42,7 @@ export default class BiomeSelectUiHandler extends UiHandler {
         return;
 
       this.biomeChoices = biomeLinks[args[0]] as Biome[];
-      this.biomeSelectBg.setTexture(`biome_select_window_${this.biomeChoices.length}`)
+      this.biomeSelectBg.setTexture(`option_select_window_${this.biomeChoices.length}`)
       this.biomesText.setText(this.biomeChoices.map(b => getBiomeName(b)).join('\n'));
       this.biomesText.setPositionRelative(this.biomeSelectBg, 16, 9);
       this.biomeSelectHandler = args[1] as Function;

src/ui/modifier-select-ui-handler.ts

@@ -1,13 +1,18 @@
 import BattleScene, { Button } from "../battle-scene";
-import { ModifierTier, ModifierType, ModifierTypeOption } from "../modifier/modifier-type";
+import { ModifierTier, ModifierTypeOption } from "../modifier/modifier-type";
 import { getPokeballAtlasKey, PokeballType } from "../data/pokeball";
 import { addTextObject, TextStyle } from "./text";
 import AwaitableUiHandler from "./awaitable-ui-handler";
 import { Mode } from "./ui";
+import { PokemonHeldItemModifier } from "../modifier/modifier";
 
 export default class ModifierSelectUiHandler extends AwaitableUiHandler {
   private overlayBg: Phaser.GameObjects.Rectangle;
   private modifierContainer: Phaser.GameObjects.Container;
+  private transferButtonContainer: Phaser.GameObjects.Container;
+
+  private lastCursor: integer = 0;
+
   public options: ModifierOption[];
 
   private cursorObj: Phaser.GameObjects.Image;
@@ -30,6 +35,14 @@ export default class ModifierSelectUiHandler extends AwaitableUiHandler {
     
     this.modifierContainer = this.scene.add.container(0, 0);
     ui.add(this.modifierContainer);
+
+    this.transferButtonContainer = this.scene.add.container((this.scene.game.canvas.width / 6) - 1, -64);
+    this.transferButtonContainer.setVisible(false);
+    ui.add(this.transferButtonContainer);
+
+    const transferButtonText = addTextObject(this.scene, -4, -2, 'Transfer', TextStyle.PARTY);
+    transferButtonText.setOrigin(1, 0);
+    this.transferButtonContainer.add(transferButtonText);
   }
 
   show(args: any[]) {
@@ -48,6 +61,11 @@ export default class ModifierSelectUiHandler extends AwaitableUiHandler {
 
     this.getUi().clearText();
 
+    const partyHasHeldItem = !!this.scene.findModifiers(m => m instanceof PokemonHeldItemModifier).length;
+
+    this.transferButtonContainer.setVisible(false);
+    this.transferButtonContainer.setAlpha(0);
+
     const typeOptions = args[0] as ModifierTypeOption[];
     for (let m = 0; m < typeOptions.length; m++) {
       const sliceWidth = (this.scene.game.canvas.width / 6) / (typeOptions.length + 2);
@@ -83,6 +101,16 @@ export default class ModifierSelectUiHandler extends AwaitableUiHandler {
     });
 
     this.scene.time.delayedCall(4000 + (hasUpgrade ? 2000 : 0), () => {
+      if (partyHasHeldItem) {
+        this.transferButtonContainer.setAlpha(0);
+        this.transferButtonContainer.setVisible(true);
+        this.scene.tweens.add({
+          targets: this.transferButtonContainer,
+          alpha: 1,
+          duration: 250
+        });
+      }
+
       this.setCursor(0);
       this.awaitingActionInput = true;
       this.onActionInput = args[1];
@@ -115,12 +143,20 @@ export default class ModifierSelectUiHandler extends AwaitableUiHandler {
       }
     } else {
       switch (button) {
+        case Button.UP:
+          if (this.cursor === this.options.length)
+            success = this.setCursor(this.lastCursor);
+          break;
+        case Button.DOWN:
+          if (this.cursor < this.options.length && this.transferButtonContainer.visible)
+            success = this.setCursor(this.options.length);
+          break;
         case Button.LEFT:
           if (this.cursor)
             success = this.setCursor(this.cursor - 1);
           break;
         case Button.RIGHT:
-          if (this.cursor < this.options.length - 1)
+          if (this.cursor < this.options.length - (this.transferButtonContainer.visible ? 0 : 1))
             success = this.setCursor(this.cursor + 1);
           break;
       }
@@ -131,18 +167,29 @@ export default class ModifierSelectUiHandler extends AwaitableUiHandler {
   }
 
   setCursor(cursor: integer): boolean {
+    const lastCursor = this.cursor;
+
     const ui = this.getUi();
     const ret = super.setCursor(cursor);
 
+    if (ret)
+      this.lastCursor = lastCursor;
+
     if (!this.cursorObj) {
       this.cursorObj = this.scene.add.image(0, 0, 'cursor');
-      this.cursorObj.setScale(2);
       this.modifierContainer.add(this.cursorObj);
     }
 
+    this.cursorObj.setScale(cursor < this.options.length ? 2 : 1);
+
+    if (cursor < this.options.length) {
       const sliceWidth = (this.scene.game.canvas.width / 6) / (this.options.length + 2);
       this.cursorObj.setPosition(sliceWidth * (cursor + 1) + (sliceWidth * 0.5) - 20, -this.scene.game.canvas.height / 12 - 20);
       ui.showText(this.options[this.cursor].modifierTypeOption.type.description);
+    } else {
+      this.cursorObj.setPosition((this.scene.game.canvas.width / 6) - 50, -60);
+      ui.showText('Transfer a held item from one POKéMON to another instead of selecting an item');
+    }
 
     return ret;
   }
@@ -165,12 +212,21 @@ export default class ModifierSelectUiHandler extends AwaitableUiHandler {
       targets: this.options,
       scale: 0.01,
       duration: 250,
-      east: 'Elastic.easeIn',
+      ease: 'Elastic.easeIn',
       onComplete: () => {
         this.options.forEach(o => o.destroy());
         this.options.splice(0, this.options.length);
       }
     });
+    if (this.transferButtonContainer.visible) {
+      this.scene.tweens.add({
+        targets: this.transferButtonContainer,
+        alpha: 0,
+        duration: 250,
+        ease: 'Cubic.easeIn',
+        onComplete: () => this.transferButtonContainer.setVisible(false)
+      })
+    }
   }
 
   eraseCursor() {

src/ui/party-ui-handler.ts

@@ -1,4 +1,4 @@
-import { CommandPhase, SummonMissingPhase } from "../battle-phases";
+import { CommandPhase } from "../battle-phases";
 import BattleScene, { Button } from "../battle-scene";
 import { PlayerPokemon, PokemonMove } from "../pokemon";
 import { addTextObject, TextStyle } from "./text";
@@ -6,6 +6,7 @@ import { Command } from "./command-ui-handler";
 import MessageUiHandler from "./message-ui-handler";
 import { Mode } from "./ui";
 import * as Utils from "../utils";
+import { PokemonHeldItemModifier } from "../modifier/modifier";
 
 const defaultMessage = 'Choose a Pokémon.';
 
@@ -15,24 +16,28 @@ export enum PartyUiMode {
   POST_BATTLE_SWITCH,
   MODIFIER,
   MOVE_MODIFIER,
+  MODIFIER_TRANSFER,
   RELEASE
 }
 
 export enum PartyOption {
+  CANCEL = -1,
   SHIFT,
   SEND_OUT,
   APPLY,
+  TRANSFER,
   SUMMARY,
   RELEASE,
   MOVE_1,
   MOVE_2,
   MOVE_3,
-  MOVE_4,
+  MOVE_4
-  CANCEL
 }
 
 export type PartySelectCallback = (cursor: integer, option: PartyOption) => void;
+export type PartyModifierTransferSelectCallback = (fromCursor: integer, index: integer, toCursor?: integer) => void;
 export type PokemonSelectFilter = (pokemon: PlayerPokemon) => string;
+export type PokemonModifierTransferSelectFilter = (pokemon: PlayerPokemon, modifier: PokemonHeldItemModifier) => string;
 export type PokemonMoveSelectFilter = (pokemonMove: PokemonMove) => string;
 
 export default class PartyUiHandler extends MessageUiHandler {
@@ -50,9 +55,13 @@ export default class PartyUiHandler extends MessageUiHandler {
   private optionsCursorObj: Phaser.GameObjects.Image;
   private options: integer[];
 
+  private transferMode: boolean;
+  private transferOptionCursor: integer;
+  private transferCursor: integer;
+  
   private lastCursor: integer = 0;
-  private selectCallback: PartySelectCallback;
+  private selectCallback: PartySelectCallback | PartyModifierTransferSelectCallback;
-  private selectFilter: PokemonSelectFilter;
+  private selectFilter: PokemonSelectFilter | PokemonModifierTransferSelectFilter;
   private moveSelectFilter: PokemonMoveSelectFilter;
 
   private static FilterAll = (_pokemon: PlayerPokemon) => null;
@@ -65,6 +74,13 @@ export default class PartyUiHandler extends MessageUiHandler {
 
   private static FilterAllMoves = (_pokemonMove: PokemonMove) => null;
 
+  public static FilterItemMaxStacks = (pokemon: PlayerPokemon, modifier: PokemonHeldItemModifier) => {
+    const matchingModifier = pokemon.scene.findModifier(m => m instanceof PokemonHeldItemModifier && (m as PokemonHeldItemModifier).matchType(modifier)) as PokemonHeldItemModifier;
+    if (matchingModifier && matchingModifier.stackCount === matchingModifier.getMaxStackCount())
+      return `${pokemon.name} has too many\nof this item!`;
+    return null;
+  };
+
   public static NoEffectMessage = 'It won\'t have any effect.';
 
   constructor(scene: BattleScene) {
@@ -166,15 +182,29 @@ export default class PartyUiHandler extends MessageUiHandler {
       if (button === Button.ACTION) {
         const option = this.options[this.optionsCursor];
         const pokemon = this.scene.getParty()[this.cursor];
-        if ((option !== PartyOption.SUMMARY && option !== PartyOption.RELEASE && option !== PartyOption.CANCEL)
+        if (this.partyUiMode === PartyUiMode.MODIFIER_TRANSFER && !this.transferMode && option !== PartyOption.CANCEL) {
+          this.startTransfer();
+          this.clearOptions();
+          ui.playSelect();
+        } else if ((option !== PartyOption.SUMMARY && option !== PartyOption.RELEASE && option !== PartyOption.CANCEL)
           || (option === PartyOption.RELEASE && this.partyUiMode === PartyUiMode.RELEASE)) {
-          let filterResult: string = this.selectFilter(pokemon);
+          let filterResult: string;
+          if (option !== PartyOption.TRANSFER) {
+            filterResult = (this.selectFilter as PokemonSelectFilter)(pokemon);
             if (filterResult === null && this.partyUiMode === PartyUiMode.MOVE_MODIFIER)
               filterResult = this.moveSelectFilter(pokemon.moveset[this.optionsCursor]);
+          } else {
+            const itemModifiers = this.scene.findModifiers(m => m instanceof PokemonHeldItemModifier
+                && (m as PokemonHeldItemModifier).pokemonId === pokemon.id) as PokemonHeldItemModifier[];
+            filterResult = (this.selectFilter as PokemonModifierTransferSelectFilter)(pokemon, itemModifiers[this.transferOptionCursor]);
+          }
           if (filterResult === null) {
             this.clearOptions();
             if (this.selectCallback) {
-              if (option === PartyOption.RELEASE)
+              if (option === PartyOption.TRANSFER) {
+                (this.selectCallback as PartyModifierTransferSelectCallback)(this.transferCursor, this.transferOptionCursor, this.cursor);
+                this.clearTransfer();
+              } else if (option === PartyOption.RELEASE)
                 this.doRelease(this.cursor);
               else {
                 const selectCallback = this.selectCallback;
@@ -241,7 +271,10 @@ export default class PartyUiHandler extends MessageUiHandler {
           this.processInput(Button.CANCEL);
         return;
       } else if (button === Button.CANCEL) {
-        if (this.partyUiMode !== PartyUiMode.FAINT_SWITCH) {
+        if (this.partyUiMode === PartyUiMode.MODIFIER_TRANSFER && this.transferMode) {
+          this.clearTransfer();
+          ui.playSelect();
+        } else if (this.partyUiMode !== PartyUiMode.FAINT_SWITCH) {
           if (this.selectCallback) {
             const selectCallback = this.selectCallback;
             this.selectCallback = null;
@@ -309,7 +342,8 @@ export default class PartyUiHandler extends MessageUiHandler {
         this.optionsCursorObj.setOrigin(0, 0);
         this.optionsContainer.add(this.optionsCursorObj);
       }
-      this.optionsCursorObj.setPosition(-86, -19 - (16 * ((this.options.length - 1) - this.optionsCursor)));
+      const wideOptions = this.partyUiMode === PartyUiMode.MODIFIER_TRANSFER;
+      this.optionsCursorObj.setPosition(-86 - (wideOptions ? 50 : 0), -19 - (16 * ((this.options.length - 1) - this.optionsCursor)));
     } else {
       changed = this.cursor !== cursor;
       if (changed) {
@@ -335,16 +369,35 @@ export default class PartyUiHandler extends MessageUiHandler {
     
     this.optionsMode = true;
 
-    this.partyMessageBox.setTexture('party_message_options');
+    const wideOptions = this.partyUiMode === PartyUiMode.MODIFIER_TRANSFER;
-    this.message.setText('Do what with this Pokémon?');
 
-    const optionsBottom = this.scene.add.image(0, 0, 'party_options_bottom');
+    this.partyMessageBox.setTexture(`party_message_options${wideOptions ? '_wide' : ''}`);
+
+    let optionsMessage = 'Do what with this Pokémon?';
+
+    switch (this.partyUiMode) {
+      case PartyUiMode.MOVE_MODIFIER:
+        optionsMessage = 'Select a move.';
+        break;
+      case PartyUiMode.MODIFIER_TRANSFER:
+        if (!this.transferMode)
+          optionsMessage = 'Select a held item to transfer.';
+        break;
+    }
+
+    this.message.setText(optionsMessage);
+
+    const optionsBottom = this.scene.add.image(0, 0, `party_options${wideOptions ? '_wide' : ''}_bottom`);
     optionsBottom.setOrigin(1, 1);
     this.optionsContainer.add(optionsBottom);
 
     const pokemon = this.scene.getParty()[this.cursor];
 
-    if (this.partyUiMode !== PartyUiMode.MOVE_MODIFIER) {
+    const itemModifiers = this.partyUiMode === PartyUiMode.MODIFIER_TRANSFER
+      ? this.scene.findModifiers(m => m instanceof PokemonHeldItemModifier && (m as PokemonHeldItemModifier).pokemonId === pokemon.id) as PokemonHeldItemModifier[]
+      : null;
+
+    if (this.partyUiMode !== PartyUiMode.MOVE_MODIFIER && (this.transferMode || this.partyUiMode !== PartyUiMode.MODIFIER_TRANSFER)) {
       switch (this.partyUiMode) {
         case PartyUiMode.SWITCH:
           if (this.cursor)
@@ -358,6 +411,9 @@ export default class PartyUiHandler extends MessageUiHandler {
         case PartyUiMode.MODIFIER:
           this.options.push(PartyOption.APPLY);
           break;
+        case PartyUiMode.MODIFIER_TRANSFER:
+          this.options.push(PartyOption.TRANSFER);
+          break;
         case PartyUiMode.RELEASE:
           this.options.push(PartyOption.RELEASE);
           break;
@@ -367,9 +423,12 @@ export default class PartyUiHandler extends MessageUiHandler {
 
       if (this.partyUiMode === PartyUiMode.SWITCH)
         this.options.push(PartyOption.RELEASE);
-    } else {
+    } else if (this.partyUiMode === PartyUiMode.MOVE_MODIFIER) {
       for (let m = 0; m < pokemon.moveset.length; m++)
         this.options.push(PartyOption.MOVE_1 + m);
+    } else {
+      for (let im = 0; im < itemModifiers.length; im++)
+        this.options.push(im);
     }
 
     this.options.push(PartyOption.CANCEL);
@@ -377,6 +436,7 @@ export default class PartyUiHandler extends MessageUiHandler {
     for (let o = 0; o < this.options.length; o++) {
       const option = this.options[this.options.length - (o + 1)];
       let optionName: string;
+      if (this.partyUiMode !== PartyUiMode.MODIFIER_TRANSFER || this.transferMode || option === PartyOption.CANCEL) {
         switch (option) {
           case PartyOption.MOVE_1:
           case PartyOption.MOVE_2:
@@ -388,10 +448,16 @@ export default class PartyUiHandler extends MessageUiHandler {
             optionName = PartyOption[option].replace(/\_/g, ' ');
             break;
         }
+      } else {
+        const itemModifier = itemModifiers[option];
+        optionName = itemModifier.type.name;
+        if (itemModifier.stackCount > 1)
+          optionName += ` (${itemModifier.stackCount})`;
+      }
 
       const yCoord = -6 - 16 * o;
-      const optionBg = this.scene.add.image(0, yCoord, 'party_options_center');
+      const optionBg = this.scene.add.image(0, yCoord, `party_options${wideOptions ? '_wide' : ''}_center`);
-      const optionText = addTextObject(this.scene, -79, yCoord - 16, optionName, TextStyle.WINDOW);
+      const optionText = addTextObject(this.scene, -79 - (wideOptions ? 50 : 0), yCoord - 16, optionName, TextStyle.WINDOW);
 
       optionBg.setOrigin(1, 1);
       optionText.setOrigin(0, 0);
@@ -400,13 +466,26 @@ export default class PartyUiHandler extends MessageUiHandler {
       this.optionsContainer.add(optionText);
     }
 
-    const optionsTop = this.scene.add.image(0, -6 - 16 * this.options.length, 'party_options_top');
+    const optionsTop = this.scene.add.image(0, -6 - 16 * this.options.length, `party_options${wideOptions ? '_wide' : ''}_top`);
     optionsTop.setOrigin(1, 1);
     this.optionsContainer.add(optionsTop);
 
     this.setCursor(0);
   }
 
+  startTransfer(): void {
+    this.transferMode = true;
+    this.transferCursor = this.cursor;
+    this.transferOptionCursor = this.optionsCursor;
+
+    this.partySlots[this.transferCursor].setTransfer(true);
+  }
+
+  clearTransfer(): void {
+    this.transferMode = false;
+    this.partySlots[this.transferCursor].setTransfer(false);
+  }
+
   doRelease(slotIndex: integer): void {
     this.showText(this.getReleaseMessage(this.scene.getParty()[slotIndex].name), null, () => {
       this.clearPartySlots();
@@ -479,6 +558,7 @@ export default class PartyUiHandler extends MessageUiHandler {
 
 class PartySlot extends Phaser.GameObjects.Container {
   private selected: boolean;
+  private transfer: boolean;
   private slotIndex: integer;
   private pokemon: PlayerPokemon;
 
@@ -550,25 +630,38 @@ class PartySlot extends Phaser.GameObjects.Container {
     this.slotHpOverlay = slotHpOverlay;
   }
 
-  select() {
+  select(): void {
     if (this.selected)
       return;
 
     this.selected = true;
 
-    this.slotBg.setTexture(`party_slot${this.slotIndex ? '' : '_main'}`, `party_slot${this.slotIndex ? '' : '_main'}${this.pokemon.hp ? '' : '_fnt'}_sel`);
+    this.updateSlotTexture();
     this.slotPb.setFrame('party_pb_sel');
   }
 
-  deselect() {
+  deselect(): void {
     if (!this.selected)
       return;
 
     this.selected = false;
 
-    this.slotBg.setTexture(`party_slot${this.slotIndex ? '' : '_main'}`, `party_slot${this.slotIndex ? '' : '_main'}${this.pokemon.hp ? '' : '_fnt'}`);
+    this.updateSlotTexture();
     this.slotPb.setFrame('party_pb');
   }
+
+  setTransfer(transfer: boolean): void {
+    if (this.transfer === transfer)
+      return;
+
+    this.transfer = transfer;
+    this.updateSlotTexture();
+  }
+
+  private updateSlotTexture(): void {
+    this.slotBg.setTexture(`party_slot${this.slotIndex ? '' : '_main'}`,
+      `party_slot${this.slotIndex ? '' : '_main'}${this.transfer ? '_swap' : this.pokemon.hp ? '' : '_fnt'}${this.selected ? '_sel' : ''}`);
+  }
 }
 
 class PartyCancelButton extends Phaser.GameObjects.Container {