aede7551a3
- Created detailed documentation for the Minecart sprite, outlining its properties, constants, collision setup, main logic, and design patterns. - Added documentation for the Pedestal sprite, including its vanilla overrides, custom logic for item interaction, and event triggering based on area context. - Introduced documentation for the Portal sprite, detailing its two-way warping system, initialization, main logic, and helper routines for seamless transitions. - Documented the Switch Track sprite, explaining its interactive behavior, state-based animation, and integration with external switches for dynamic track manipulation.
87 lines
3.6 KiB
Markdown
87 lines
3.6 KiB
Markdown
# Bug Net Kid (Sick Kid)
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## Overview
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The Bug Net Kid, also referred to as the Sick Kid, is an NPC sprite that plays a role in a quest involving the "Song of Healing" and the acquisition of the Boots (referred to as Bug Net in the comments). This sprite is implemented by overriding vanilla game code to introduce custom interactions and progression.
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## Vanilla Overrides
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This sprite extensively uses `pushpc`/`pullpc` blocks and `org` directives to inject custom logic into existing vanilla routines. This approach allows for modifying the behavior of a vanilla NPC without creating a new sprite ID.
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* **`org $068D7F`**: Overrides the vanilla `SpritePrep_SickKid` routine.
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* **`org $06B962`**: Overrides a routine related to the kid's resting state (`BugNetKid_Resting`).
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* **`org $06B9C6`**: Overrides a routine responsible for granting the item (`BugNetKid_GrantBugNet`).
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## `SickKid_CheckForSongOfHealing`
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This routine is a core component of the Bug Net Kid's logic. It checks if the "Song of Healing" has been played by examining a `SongFlag` (likely a WRAM address like `$7E001F`). If the song has been played, it updates internal sprite state variables (`$0D80, X`, `$02E4`) and clears the `SongFlag`.
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```asm
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SickKid_CheckForSongOfHealing:
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{
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LDA.b SongFlag : CMP.b #$01 : BNE .no_song
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INC $0D80, X
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INC $02E4
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STZ.b SongFlag
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.no_song
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RTL
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}
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```
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## `SpritePrep_SickKid` (Initialization)
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This routine is executed when the Sick Kid sprite is initialized. It checks an SRAM flag (`$7EF355`) to determine if Link has already obtained the Boots. If so, it sets `$0D80, X` to `$03`. It also increments `SprBulletproof, X`, making the kid invulnerable to attacks.
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```asm
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SpritePrep_SickKid:
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{
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LDA.l $7EF355 : BEQ .no_boots
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LDA.b #$03 : STA $0D80, X
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.no_boots
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INC.w SprBulletproof, X
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RTS
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}
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```
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## `BugNetKid_Resting` (Main Logic)
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This routine controls the kid's behavior when not actively granting an item. It checks for player preoccupation and damage, and crucially, calls `SickKid_CheckForSongOfHealing`. If Link has not yet received the Boots, it displays a solicited message to the player.
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```asm
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BugNetKid_Resting:
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{
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JSL Sprite_CheckIfPlayerPreoccupied : BCS .dont_awaken
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JSR Sprite_CheckDamageToPlayer_same_layer : BCC .dont_awaken
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JSL SickKid_CheckForSongOfHealing
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LDA.l $7EF355
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CMP.b #$01 : BCC .no_boots
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.dont_awaken
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RTS
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.no_boots
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LDA.b #$04
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LDY.b #$01
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JSL Sprite_ShowSolicitedMessageIfPlayerFacing
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RTS
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}
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```
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## `BugNetKid_GrantBugNet` (Item Granting)
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This routine is responsible for giving Link the Boots. It sets the item ID (`LDY.b #$4B`), clears a flag (`$02E9`), calls `JSL Link_ReceiveItem` to add the item to Link's inventory, and updates internal sprite state variables (`$0D80, X`, `$02E4`).
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```asm
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BugNetKid_GrantBugNet:
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{
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; Give Link the Boots
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LDY.b #$4B
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STZ $02E9
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PHX
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JSL Link_ReceiveItem
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PLX
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INC $0D80, X
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STZ $02E4
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RTS
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}
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```
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## Design Patterns
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* **Vanilla Override**: This sprite is a prime example of overriding vanilla game code to introduce new NPC interactions and quest elements without creating entirely new sprite definitions.
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* **Quest/Item Gating**: The sprite's behavior and the ability to receive the Boots are directly tied to specific game progression flags, such as the `SongFlag` and the SRAM flag for the Boots (`$7EF355`).
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* **NPC Interaction**: The sprite interacts with the player by displaying messages and granting a key item, driving forward a specific questline.
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* **Global Flags and SRAM Usage**: Utilizes global WRAM flags (`$02E4`, `SongFlag`) and SRAM (`$7EF355`) to maintain and track the state of the quest across game sessions.
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