Miku: implement Birthright multi-note firing mechanic

Author: vulpya

README.md

@@ -22,10 +22,12 @@ Use her **Microphone** to inspire your audience!
 Due to losing her voice, she starts with only Glitch Notes.
 
 Enemies may drop **Lost Notes** when slain.
-Each **Note** grants a **different effect**.
+Each **Lost Note** grants a **different effect**.
 
 Use the **Broken Microphone** to switch melodies.
 
+With **Birthright** she loses even more control of her broken voice, firing multiple Lost Notes at onces.
+
 ## Mod Compatibility
 
 ### External Item Descriptions Support
@@ -37,11 +39,10 @@ For missing or wrong descriptions, please open a new Issue.
 ## Roadmap
 
 - Finish Tainted Miku.
-- Add Tainted Miku Birthright effect.
+- Sound Effects.
 - More Miku-themed items.
 - Improved sprites and animations.
 - Better visual effects.
-- Expanded mechanics and balance improvements.
 
 ## Disclaimer
 

TODO.md

@@ -9,6 +9,7 @@
 - [x] Add 'Passive Active Item' to switch between notes.
 - [x] Add Synergies to Tainted Miku. (e.g. Brimstone, Epic Fetus)
 - [ ] Add MCM Compat.
+- [ ] Setup Tests.
 
 ## TODO: Miku
 
@@ -31,5 +32,5 @@
   - [ ] TODO: Synergy ideas.
 - [x] Fix fire rate multiplier issues with several items.
   - [x] Fix Monstro's Lung.
-- [ ] Add Birthright for Tainted Miku.
+- [x] Add Birthright for Tainted Miku.
 - [ ] Add Tainted Miku Icons & Controls.

mod/content/players.xml

@@ -1,4 +1,4 @@
 <players root="gfx/characters/costumes/" portraitroot="gfx/ui/stage/" nameimageroot="gfx/ui/boss/">
   <player name="Miku" skin="Character_Miku.png" nameimage="PlayerName_Miku.png" hp="6" portrait="PlayerPortrait_Miku.png" skinColor="-1" costume="104" costumeSuffix="miku" birthright="Lucky idol" />
-  <player name="Miku" skin="Character_Miku_b.png" nameimage="PlayerName_Miku.png" hp="4" armor="2" keys="1" portrait="PlayerPortrait_Miku.png" skinColor="-1" bSkinParent="Miku" costume="104" costumeSuffix="mikub" />
+  <player name="Miku" skin="Character_Miku_b.png" nameimage="PlayerName_Miku.png" hp="4" armor="2" keys="1" portrait="PlayerPortrait_Miku.png" skinColor="-1" bSkinParent="Miku" costume="104" costumeSuffix="mikub" birthright="Broken Encore" />
 </players>

mod/metadata.xml

@@ -25,10 +25,11 @@ I get a lot of comments like the games not launching or the mod breaks the game.
 • Use her active item, the [b]Microphone[/b], to inspire your audience!
 
 [b]Tainted Miku (Work In Progress)[/b]
+• [NEW] Unique birthright effect.
 • Having lost her voice, she starts the run firing highly unstable [b]Glitch Notes[/b].
 • Slain enemies drop [b]Lost Notes[/b] onto the floor.
 • Collecting different Lost Notes grants various dynamic gameplay effects.
-• Use the [b]Broken Microphone[/b] to rapidly switch melodies.
+• Use the [b]Broken Microphone[/b] to switch between melodies.
 
 ----------------------------------------------------------------------
 [h2]Mod Compatibility[/h2]
@@ -58,6 +59,6 @@ This is a non-commercial, fan-made mod created as a personal project for fun. Al
 • [url=https://steamcommunity.com/profiles/76561198102520074]ale[/url] — For creating the amazing Miku/Vocaloid sprites!
 • [url=https://steamcommunity.com/id/thearexz]Arexz[/url] — For helping with custom sprite editing and refinement.
   </description>
-  <version>0.3.1</version>
+  <version>0.4.0</version>
   <visibility />
 </metadata>

src/characters/Miku/MikuTaintedCharacter.ts

@@ -24,6 +24,7 @@ import {
   ModCallbackCustom,
   ReadonlyMap,
   spawnEffect,
+  spawnTear,
   VectorZero,
 } from "isaacscript-common";
 import type { EIDExtended } from "../../compat/EID";
@@ -75,7 +76,9 @@ export interface TaintedMikuSaveData {
 
 const NAME = "Miku";
 const DESCRIPTION = "A twisted idol, using enemies as her melody.";
-const BIRTHRIGHT_DESC = "TODO";
+const BIRTHRIGHT_DESC =
+  "Her fractured melody splits apart, causing multiple Lost Notes to fire with every shot.";
+const BIRTHRIGHT_MULTI_SHOT = 5;
 const HAIR = Isaac.GetCostumeIdByPath("gfx/characters/Character_MikuHead.anm2");
 const POCKET_ACTIVE = CollectibleTypeCustom.BROKEN_VOICE;
 const NULL_ITEM = CollectibleTypeCustom.MIKU_IDOL;
@@ -175,41 +178,6 @@ export class MikuTaintedCharacter extends Character {
     }
   }
 
-  /**
-   * Called after Tainted Miku is initialized.
-   *
-   * Reads the mod save data to set the data for Tainted Miku on a continued run.
-   *
-   * @param player The player entity being initialized.
-   */
-  @Callback(ModCallback.POST_PLAYER_INIT, PlayerVariant.PLAYER)
-  override postPlayerInit(player: EntityPlayer): void {
-    super.postPlayerInit(player);
-    if (!isMiku(player, true)) {
-      return;
-    }
-
-    const saved = SAVE_DATA.mikuBs[player.ControllerIndex.toString()];
-    if (!saved) {
-      return;
-    }
-
-    const playerData = getData<TaintedMikuData>(player);
-
-    playerData.erased = saved.erased ?? [];
-    playerData.notes = saved.notes ?? [];
-    playerData.unlockedNotes = saved.unlockedNotes ?? [];
-    playerData.attackMode = saved.attackMode ?? MikuNoteMode.GLITCH;
-
-    playerData.storedCollectibles = new Set(saved.storedCollectibles ?? []);
-
-    for (const collectible of playerData.storedCollectibles) {
-      if (!player.HasCollectible(collectible)) {
-        player.AddCollectible(collectible);
-      }
-    }
-  }
-
   @CallbackCustom(
     ModCallbackCustom.POST_PLAYER_UPDATE_REORDERED,
     PlayerVariant.PLAYER,
@@ -248,6 +216,41 @@ export class MikuTaintedCharacter extends Character {
     }
   }
 
+  /**
+   * Called after Tainted Miku is initialized.
+   *
+   * Reads the mod save data to set the data for Tainted Miku on a continued run.
+   *
+   * @param player The player entity being initialized.
+   */
+  @Callback(ModCallback.POST_PLAYER_INIT, PlayerVariant.PLAYER)
+  override postPlayerInit(player: EntityPlayer): void {
+    super.postPlayerInit(player);
+    if (!isMiku(player, true)) {
+      return;
+    }
+
+    const saved = SAVE_DATA.mikuBs[player.ControllerIndex.toString()];
+    if (!saved) {
+      return;
+    }
+
+    const playerData = getData<TaintedMikuData>(player);
+
+    playerData.erased = saved.erased ?? [];
+    playerData.notes = saved.notes ?? [];
+    playerData.unlockedNotes = saved.unlockedNotes ?? [];
+    playerData.attackMode = saved.attackMode ?? MikuNoteMode.GLITCH;
+
+    playerData.storedCollectibles = new Set(saved.storedCollectibles ?? []);
+
+    for (const collectible of playerData.storedCollectibles) {
+      if (!player.HasCollectible(collectible)) {
+        player.AddCollectible(collectible);
+      }
+    }
+  }
+
   @Callback(ModCallback.EVALUATE_CACHE, CacheFlag.FIRE_DELAY)
   override cacheFireDelay(player: EntityPlayer): void {
     if (!isMiku(player, true)) {
@@ -277,6 +280,7 @@ export class MikuTaintedCharacter extends Character {
   @Callback(ModCallback.POST_FIRE_TEAR)
   override postFireTear(tear: EntityTear): void {
     const player = getPlayerFromEntity(tear);
+
     if (!player || !isMiku(player, true)) {
       return;
     }
@@ -292,21 +296,32 @@ export class MikuTaintedCharacter extends Character {
       return;
     }
 
-    const note = notes[0];
-    if (!note) {
-      return;
-    }
+    const amount = player.HasCollectible(CollectibleType.BIRTHRIGHT)
+      ? BIRTHRIGHT_MULTI_SHOT
+      : 1;
 
-    const noteData = NOTE_TYPE_DATA[note.subType];
-    const tearData = getData<GlitchNoteTearData>(tear);
+    const activeNotes = notes.slice(0, amount);
 
-    noteData.applyEffect?.(player, tear);
-    noteData.onFireTear?.(player, tear);
-    tearData.color = noteData.color;
+    for (const [i, note] of activeNotes.entries()) {
+      let noteTear = tear;
 
-    note.remainingUses--;
-    if (note.remainingUses <= 0) {
-      notes.shift();
+      if (i > 0) {
+        noteTear = spawnTear(
+          tear.Variant,
+          tear.SubType,
+          tear.Position,
+          tear.Velocity,
+          player,
+        );
+
+        noteTear.CollisionDamage = tear.CollisionDamage;
+        noteTear.Scale = tear.Scale;
+      }
+
+      this.applyNoteEffect(player, noteTear, note);
+
+      const tearData = getData<GlitchNoteTearData>(noteTear);
+      setTearColor(noteTear, tearData, noteTear.GetDropRNG());
     }
   }
 
@@ -712,4 +727,25 @@ export class MikuTaintedCharacter extends Character {
       );
     }
   }
+
+  private applyNoteEffect(
+    player: EntityPlayer,
+    tear: EntityTear,
+    note: NoteInstance,
+  ): void {
+    const noteData = NOTE_TYPE_DATA[note.subType];
+    const tearData = getData<GlitchNoteTearData>(tear);
+
+    noteData.applyEffect?.(player, tear);
+    noteData.onFireTear?.(player, tear);
+
+    tearData.color = noteData.color;
+
+    note.remainingUses--;
+
+    if (note.remainingUses <= 0) {
+      const playerData = getData<TaintedMikuData>(player);
+      playerData.notes = playerData.notes?.filter((n) => n !== note);
+    }
+  }
 }

src/entities/tears/GlitchNoteTear/GlitchNoteTear.ts

@@ -19,6 +19,8 @@ import { Tear } from "../Tear";
 
 export interface GlitchNoteTearData extends TearData {
   onHitEnemy?: (entity: EntityNPC) => void;
+  glitchTime?: number;
+  initializedColor?: boolean;
 }
 
 export class GlitchNoteTear extends Tear {
@@ -46,13 +48,42 @@ export class GlitchNoteTear extends Tear {
     spawnPoof(tear, EffectVariant.TEAR_POOF_B);
   }
 
-  private applyEffect(tear: EntityTear) {
+  private applyEffect(tear: EntityTear): void {
     const tearData = getData<GlitchNoteTearData>(tear);
+
+    tearData.glitchTime ??= 0;
+    tearData.glitchTime++;
+
     const rng = tear.GetDropRNG();
 
-    setTearColor(tear, tearData, rng);
+    if (!(tearData.initializedColor ?? false)) {
+      setTearColor(tear, tearData, rng);
+      tearData.initializedColor = true;
+    }
+
+    const maxTime = 20;
+    const intensity = Math.min(tearData.glitchTime / maxTime, 1);
+
+    const minBrightness = 0.15;
+    const brightness = minBrightness + (1 - minBrightness) * (1 - intensity);
+
+    const originalColor = tearData.color;
+
+    tear.SetColor(
+      Color(
+        brightness * (originalColor?.R ?? 1),
+        brightness * (originalColor?.G ?? 1),
+        brightness * (originalColor?.B ?? 1),
+        1,
+        0,
+        0,
+        0,
+      ),
+      -1,
+      1000,
+    );
 
-    applyPositionJitter(tear, rng);
-    applyRotationShift(tear, rng);
+    applyPositionJitter(tear, rng, intensity);
+    applyRotationShift(tear, rng, intensity);
   }
 }

src/util/effects.ts

@@ -27,33 +27,47 @@ export const setTearColor = (
 /**
  * Applies a subtle "floaty" jitter effect to the tear's position.
  *
- * - This function randomly offsets the tear's position slightly, creating an organic and jittery
- *   effect in the tear's movement. The intensity of the jitter is determined by a random chance and
- *   the RNG value.
+ * - This function randomly offsets the tear's position slightly, creating an kinda organic and
+ *   jittery effect in the tear's movement.
+ * - The intensity increases the strength of the jitter.
  *
  * @param tear The tear entity whose position will be modified by the jitter effect.
  * @param rng A random number generator instance used to determine the jitter amount.
+ * @param intensity Strength multiplier for the effect (0-1).
  */
-export const applyPositionJitter = (tear: EntityTear, rng: RNG): void => {
+export const applyPositionJitter = (
+  tear: EntityTear,
+  rng: RNG,
+  intensity = 1,
+): void => {
   if (rollChance(15, rng, 0)) {
-    const jitterX = (getRandom(rng) - 0.5) * 0.3;
-    const jitterY = (getRandom(rng) - 0.5) * 0.3;
+    const amount = 0.3 * intensity;
+
+    const jitterX = (getRandom(rng) - 0.5) * amount;
+    const jitterY = (getRandom(rng) - 0.5) * amount;
+
     tear.Position = tear.Position.add(Vector(jitterX, jitterY));
   }
 };
 
 /**
  * Applies random rotation shifts to the tear, creating a less rigid, more dynamic motion.
  *
- * - This function adds a small random shift to the tear's rotation. The shift amount is determined
- *   by the RNG.
+ * - The rotation distortion increases with the intensity value.
  *
  * @param tear The tear entity whose rotation will be modified by the rotation shift.
  * @param rng A random number generator instance used to determine the rotation shift amount.
+ * @param intensity Strength multiplier for the effect (0-1).
  */
-export const applyRotationShift = (tear: EntityTear, rng: RNG): void => {
+export const applyRotationShift = (
+  tear: EntityTear,
+  rng: RNG,
+  intensity = 1,
+): void => {
   if (rollChance(20, rng, 0)) {
-    const rotationShift = (getRandom(rng) - 0.5) * 4;
+    const amount = 4 * intensity;
+
+    const rotationShift = (getRandom(rng) - 0.5) * amount;
     tear.SpriteRotation += rotationShift;
   }
 };