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.
89 lines
4.2 KiB
Markdown
89 lines
4.2 KiB
Markdown
# Fortune Teller
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## Overview
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The `fortune_teller.asm` file is not a complete sprite definition but rather a set of routines and data that override and extend the behavior of the vanilla Fortune Teller NPC. Its primary function is to provide highly context-sensitive messages to Link, offering guidance or commentary based on his current inventory, collected items, and overall game progression.
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## Vanilla Overrides
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This file directly modifies existing vanilla code related to the Fortune Teller:
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* **`org $0DC829`**: Overrides the `FortuneTellerMessage` data table, which contains the message IDs that the Fortune Teller can display.
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* **`org $0DC849`**: Overrides the `FortuneTeller_PerformPseudoScience` routine, which is the core logic for determining and displaying messages.
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## `FortuneTellerMessage` Data Table
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This table stores a sequence of byte values, each representing a message ID. These IDs correspond to specific dialogue options that the Fortune Teller can present to Link.
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```asm
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org $0DC829
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FortuneTellerMessage:
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.low
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#_0DC829: db $EA ; MESSAGE 00EA
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#_0DC82A: db $EB ; MESSAGE 00EB
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#_0DC82B: db $EC ; MESSAGE 00EC
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#_0DC82C: db $ED ; MESSAGE 00ED
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#_0DC82D: db $EE ; MESSAGE 00EE
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#_0DC82E: db $EF ; MESSAGE 00EF
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#_0DC82F: db $F0 ; MESSAGE 00F0
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#_0DC830: db $F1 ; MESSAGE 00F1
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#_0DC831: db $F6 ; MESSAGE 00F6
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#_0DC832: db $F7 ; MESSAGE 00F7
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#_0DC833: db $F8 ; MESSAGE 00F8
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#_0DC834: db $F9 ; MESSAGE 00F9
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#_0DC835: db $FA ; MESSAGE 00FA
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#_0DC836: db $FB ; MESSAGE 00FB
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#_0DC837: db $FC ; MESSAGE 00FC
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#_0DC838: db $FD ; MESSAGE 00FD
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.high
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#_0DC839: db $00
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; ... (rest of the table)
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```
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## `FortuneTeller_PerformPseudoScience` Routine
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This routine is the central logic for the custom Fortune Teller. It dynamically selects which message to display to Link based on a series of checks against his inventory and various game progression flags stored in SRAM.
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* **Initializations**: Performs some initial state manipulations (`STZ.w $0DC0,X`, `INC.w $0D80,X`, `STZ.b $03`).
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* **Progression Check (`$7EF3D6`)**: Determines a base message category based on a custom progression flag.
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* **Extensive Item and Game State Checks**: The routine then proceeds through a series of conditional checks, each corresponding to a specific item or game event. For example, it checks for:
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* `$7EF344` (Mushroom/Powder)
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* `$7EF37A` (Crystals, specifically if Tail Palace is beaten)
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* `$7EF355` (Boots)
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* `$7EF356` (Flippers)
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* `$7EF345` (Fire Rod)
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* `$7EF37B` (Magic Upgrade)
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* `$7EF354` (Glove)
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* `$7EF358` (Wolf Mask)
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* `$7EF3C9` (Smithy Rescued flag)
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* `$7EF352` (Cape)
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* `$7EF354` (Titans Mitt)
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* `$7EF359` (Sword level)
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* **Message Display**: Based on these checks, it calls `FortuneTeller_PrepareNextMessage` with the appropriate message index and then `FortuneTeller_DisplayMessage` to show the message to the player.
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```asm
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FortuneTeller_PerformPseudoScience:
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#_0DC849: STZ.w $0DC0,X
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#_0DC84C: INC.w $0D80,X
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#_0DC84F: STZ.b $03
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#_0DC851: LDA.l $7EF3D6
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#_0DC855: CMP.b #$02
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#_0DC857: BCS .map_icon_past_pendants
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#_0DC859: STZ.b $00
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#_0DC85B: STZ.b $01
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#_0DC85D: JMP.w FortuneTeller_DisplayMessage
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.map_icon_past_pendants
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#_0DC860: LDA.l $7EF344
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#_0DC864: BNE .have_shroom_or_powder
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#_0DC866: LDA.b #$02
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#_0DC868: JSR FortuneTeller_PrepareNextMessage
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#_0DC86B: BCC .have_shroom_or_powder
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#_0DC86D: JMP.w FortuneTeller_DisplayMessage
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; ... (rest of the conditional item checks)
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```
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## Design Patterns
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* **Vanilla Override**: This file exemplifies how to directly modify and extend the behavior of existing vanilla NPCs through targeted code injection.
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* **Context-Sensitive Dialogue**: The Fortune Teller's messages are highly dynamic and personalized, adapting to Link's current inventory and game progression. This creates a more engaging and responsive NPC interaction.
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* **Quest Progression Tracking**: The routine extensively utilizes SRAM flags and item possession checks to track Link's progress through various quests and milestones, influencing the dialogue provided.
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* **Modular Message System**: The use of `FortuneTeller_PrepareNextMessage` and `FortuneTeller_DisplayMessage` allows for a structured and modular approach to managing and displaying NPC dialogue.
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