Perpetual Day or Perpetual Night

A Minecraft mod that switches between Perpetual Day / Perpetual Night / Normal Cycle modes via commands, introducing hardcore survival mechanics such as temperature, thirst, water purification, and entity enhancement. 跳转到中文介绍: README.md

Platform Support

Requires Fabric Loader 0.19.3+ and Fabric API 0.92.11+1.20.1.

Features

• Three-Mode Switching: Perpetual Day (locked at noon), Perpetual Night (locked at midnight), Normal Cycle — switch freely between all three without any key
• Temperature System: Body temperature is affected by biome / dimension / time / weather / altitude / nearby blocks / held items / armor insulation; extreme heat burns, extreme cold freezes
• Drift Accumulation: In Perpetual Day / Night modes, temperature drift accumulates by dailyDriftAmount (default 1°C) per day without decay; the longer the perpetual mode, the more extreme; switching between Day↔Night inverts the drift directly
• Normal Mode Safety: Pure environmental temperature is clamped to ±normalSafeRange (default ±60°C), preventing death; block and held-item effects are not clamped and can still be lethal
• Thirst System: Players have a hydration value (default initial 100) that drains over time; different water sources have different effects (freshwater lakes are safe, oceans / salt lakes / normal water have a 75% dehydration chance)
• Water Purification: Dirty water bottles / buckets must be smelted in furnace / blast furnace / smoker before drinking
• Direct Drinking: Right-click water surface while empty-handed to drink; freshwater lakes are 100% safe, other water sources have a 75% dehydration chance
• Entity Enhancement: In Perpetual Day / Night modes, hostile entities gain enhanced attributes and AI (speed / attack / health boost; neutral mobs actively track players)
• HUD Display: Body temperature and hydration are merged and displayed on the action bar without polluting chat
• Data Persistence: Player temperature / thirst data + global drift value persist across sessions; server restarts do not lose data

Mode Details

Drift Transition Rules

| Switch Scenario | Drift Handling | |---|---| | Perpetual Day → Night | +N°C → -N°C, continues accumulating toward cold | | Perpetual Night → Day | -N°C → +N°C, continues accumulating toward hot | | Perpetual Day/Night → Normal | No inversion, decays to 0 at driftDecayRate | | Normal → Perpetual Day/Night | Starts from 0, accumulates positively/negatively |

Commands

All commands require OP permission (default level 2). | Command | Description | |---|---| | /pdopn day | Switch to Perpetual Day mode | | /pdopn night | Switch to Perpetual Night mode | | /pdopn cycle | Restore normal day-night cycle | | /pdopn status | Show current mode | | /pdopn temp | Show your body temperature | | /pdopn temp set <value> | Set your body temperature (-100 to 100) | | /pdopn temp maxdays <days> | Set max survival days (reference only) | | /pdopn temp hud | Toggle temperature HUD display | | /pdopn thirst | Show your hydration level | | /pdopn thirst set <value> | Set your hydration level (0 to 100) | | /pdopn drift | Show the current accumulated temperature drift (works from console) | | /pdopn drift reset | Clear accumulated drift and day counter without restarting the server (works from console) | | /pdopn reload | Reload pdopn.json (works from console) |

temp maxdays currently only acts as the threshold for a one-time warning (HUD / ActionBar) when that many perpetual days have elapsed. It does not end the game or alter temperature math.

Temperature System

Temperature Factors

Cooling Options

Hot environments now have two usable cooling paths (previously water had no effect on body temperature, leaving perpetual-day + desert unsurvivable): | Method | Effect | |---|---| | Standing in water | Body temperature moves toward the water temperature. Frozen ocean -25°C, frozen river -20°C, cold ocean +2°C, normal river/lake +12°C, warm ocean +22°C, jungle +20°C | | Drinking pure water | -6°C per bottle (-20°C per bucket) over 10 seconds; direct freshwater drink -3°C, unsafe water -2°C |

Water temperature is determined by biome; it only cools when colder than your body, so standing in warm water never heats you up. Armor insulation also slows cooling (thick armor traps heat). Below 0°C body temperature, cold drinks stop cooling so you cannot freeze yourself.

Temperature Effects

Lethal Temperature Damage Types

The lethal damage at the temperature extremes uses custom damage types, so the death message is mod-specific rather than the generic vanilla text: | Case | Damage type | Death message | |---|---|---| | ≥ 100°C | pdopn:heat | %s's body temperature ran away and was consumed by extreme heat | | ≤ -100°C | pdopn:cold | %s's body temperature ran away and froze to death |

Defined in data/pdopn/damage_type/heat.json and cold.json. The translation key is "death.attack." + message_id, i.e. death.attack.pdopn.heat / death.attack.pdopn.cold (plus .player variants used when there is a killer).

Thirst System

Thirst Stages

Water Source Drinking Effects

Water Purification Recipes

These recipes use vanilla recipe types (minecraft:smelting / blasting / smoking) with a vanilla water bottle or water bucket as input.

⚠️ Known limitation: vanilla Ingredient JSON only supports item / tag, and its matching logic (isItemEqual → isOf(Item)) does not compare NBT, so it cannot match "a water bottle" specifically. As a result, any potion (Healing / Strength / Fire Resistance, etc.) smelted in a furnace will turn into a Pure Water Bottle. Do not put valuable potions in a furnace.

History: a custom RecipeSerializer + custom RecipeType was attempted to filter the input, but blocks index recipes by type and look them up via RecipeManager#getAllOfType (recipes.getOrDefault(type, ...)), so a custom type makes the recipe land in a bucket that is never queried — appearing as "the recipe exists but the furnace ignores it". To keep the recipes working, they were reverted to vanilla recipe types.

Drinking Cooldown

Direct drinking (empty-handed right-click on water) has a 40-tick (2 seconds) cooldown to prevent rapid spamming.

Entity Enhancement

Perpetual Day Mode

Health is scaled by a multiplier relative to the base value (vanilla 20-HP zombie → 200). Older versions used a fixed 200, which actually weakened high-HP mobs such as the Warden; it is now a true multiplier. Attribute modifiers use MULTIPLY_TOTAL, so ratios such as ×1.5 / ×0.7 hold exactly for any entity.

Perpetual Night Mode

Health is clamped at 1024, so some entities cannot reach the nominal value at high multipliers. Neutral hostile mobs (Enderman, Spider, Zombie Piglin, etc.) actively track players in Perpetual Day / Night modes (via injected ActiveTargetGoal).

Game Rules

The mod registers a set of per-world game rules, changeable at runtime with vanilla /gamerule (OP required). They also appear in the "Create World → Game Rules" screen. | Game Rule | Default | Description | |---|---|---| | pdopnTemperature | true | Master switch for the temperature system | | pdopnThirst | true | Master switch for the thirst system | | pdopnDrift | true | Drift accumulation. When off, the day/night time lock still works — drift simply stops accumulating | | pdopnMaxDrift | 100 | Absolute drift cap (°C). 0 = unlimited; default ±100 matches the lethal threshold, capping around day 100 | | pdopnBlockTemp | true | Temperature influence of nearby dangerous blocks (lava / fire / ice, etc.) | | pdopnLethalDamage | true | Lethal temperature and dehydration damage. When off you still overheat / freeze / dehydrate, but do not die | | pdopnMobBoost | true | Hostile mob attribute enhancement | | pdopnNeutralAggro | true | Neutral mobs (Enderman / Spider, etc.) actively track players | | pdopnHudDefault | true | Default HUD state for new players (players who turned it off keep their choice) | | pdopnMaxDaysEnforce | false | Upgrade maxDays from "warning only" to enforced: auto-revert to Normal cycle on expiry |

Why game rules instead of config options

pdopn.json lives in .minecraft/config/ and applies to every world on the server, while mode and drift are per-world state and temperature is per-player state. Game rules come with /gamerule, OP permission checks, world-save persistence and client sync out of the box — none of which needs reimplementing. Division of labour: the config supplies global defaults, game rules supply per-world overrides. Rules are strictly "switch / cap" semantics; concrete numbers stay in the config so the two sources never fight each other.

Typical use: /gamerule pdopnDrift false — keep the perpetual-day scenery without the ever-rising temperature pressure. Or /gamerule pdopnMaxDrift 60 — cap drift at ±60°C so it stays extreme but survivable.

Configuration

Config file is located at .minecraft/config/pdopn/pdopn.json; apply changes with /pdopn reload or by restarting the server. All concrete temperature / thirst numbers live here.

Temperature Config

Thirst Config

Entity Enhancement Options

Purpose: avoid conflicts with mods that also rewrite mob attributes (elite mobs, epic fight, etc.). For example "blacklist": ["modid:elite_zombie"], or "whitelist": ["minecraft:zombie", "minecraft:skeleton"].

Config Version

Use /pdopn reload to apply config changes without restarting the server. If configVersion in the file is older than the current one, the mod fills in new fields and writes the file back.

Installation

1. Install Minecraft 1.20.1
2. Install Fabric Loader 0.19.3 or later
3. Download Fabric API 0.92.11+1.20.1
4. Download this mod's jar file
5. Place both Fabric API and this mod's jar into the .minecraft/mods/ directory
6. Launch the game

Build & Development

Project Structure

Perpetual day or perpetual night/
├── src/main/java/yifei/pdopn/
│   ├── PerpetualDayOrPerpetualNight.java   # Main entry
│   ├── client/                             # Client entry
│   ├── command/                            # Command system
│   ├── config/                             # Config management
│   ├── entity/                             # Entity attribute modification
│   ├── hud/                                # HUD rendering
│   ├── items/                              # Pure water bottle / bucket
│   ├── mixin/                              # Mixin injections
│   ├── mode/                               # Mode enum
│   ├── temperature/                        # Temperature system
│   └── thirst/                             # Thirst system
├── src/main/resources/
│   ├── assets/pdopn/                      # Resources (lang/models/textures)
│   └── data/pdopn/                         # Data files (recipes)
├── gradle.properties
└── README.md

Build Command

./gradlew build            # Output → build/libs/pdopn-1.0.0 Fabric.jar

The build also auto-generates a -sources.jar source package.

Tech Stack

• Loader: Fabric Loader 0.19.3
• API: Fabric API 0.92.11+1.20.1
• Mappings: Yarn 1.20.1+build.10
• Build Tool: Fabric Loom 1.17-SNAPSHOT
• Java: 17

License

This project is licensed under the MIT License, see LICENSE.