Modpack Integration

Modpack Integration

2.0.0 makes the entire bow & arrow material system data-driven. Modpack makers can add new bow limbs, risers, strings, arrow heads, shafts, and fletchings — with their own stats and behaviors — purely in JSON. No companion mod required.

The canonical reference is MODPACK_INTEGRATION.md in the mod's source repo. This wiki page is a navigable summary.

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At a glance

A "material" is one of six things. Each lives in its own datapack registry:

Slot	Datapack folder
Bow limb	data/<pack>/fletcherstrestle/bow_limb/<id>.json
Bow riser	data/<pack>/fletcherstrestle/bow_riser/<id>.json
Bow string	data/<pack>/fletcherstrestle/bow_string/<id>.json
Arrow head	data/<pack>/fletcherstrestle/arrow_head/<id>.json
Arrow shaft	data/<pack>/fletcherstrestle/arrow_shaft/<id>.json
Arrow fletching	data/<pack>/fletcherstrestle/arrow_fletching/<id>.json

Each JSON has the same shape:

{
  "ingredient": { "tag": "c:ingots/steel" },
  "stats": { "damage_multiplier": 1.5 },
  "texture": "mypack:item/modular_bow/limbs/steel",
  "effects": [
    { "type": "fletcherstrestle:apply_effect",
      "effect": "minecraft:wither",
      "duration": 80,
      "amplifier": 1 }
  ]
}

• ingredient — full vanilla Ingredient codec (item, tag, or list).
• stats — typed per part. Schemas in MODPACK_INTEGRATION.md.
• texture — optional override; falls back to a conventional path in the material's own namespace.
• effects — optional list of declarative behaviors.

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The effect vocabulary

19 built-in effect types cover everything the vanilla materials do:

On-hit damage modifiers (run BEFORE damage applies, on head/shaft/fletching defs):

• damage_multiplier — flat scale
• damage_multiplier_if_target_below_health — executioner (crimson shaft)
• damage_multiplier_on_backstab — pale_oak shaft
• damage_multiplier_by_distance — weighted_blunt head
• damage_multiplier_if_target_armored — bodkin_point head
• pierce_level — dark_oak shaft

On-hit side effects (after damage, on head/shaft/fletching):

• apply_effect — broadhead bleed, mangrove slowness
• heal_shooter — cherry shaft
• pull_target_to_shooter — barbed_tip head
• teleport_swap_with_target — warped shaft
• drop_self_on_hit — bound fletching

Tick-time (every tick in flight, on head/shaft/fletching):

• set_velocity_multiplier_at_tick — acacia shaft mid-flight boost
• subtle_homing — serrated fletching magnetism

Block-hit (on head/shaft/fletching):

• bounce_on_block — jungle shaft ricochet

Bow / crossbow release (on limb/riser/string):

• ignite_arrow — crimson limb
• set_arrow_no_gravity — warped limb
• set_arrow_flag — spruce punch, copper conductive
• apply_effect_to_shooter — acacia limb speed buff

Scripted escape hatch (any def):

• scripted_callback — invokes a Java-side handler registered by id; KubeJS scripts or companion mods register the handler.

The full parameter list for each is in MODPACK_INTEGRATION.md → Effects reference.

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End-to-end example: a Steel Spike arrow head

data/mypack/fletcherstrestle/arrow_head/steel_spike.json:

{
  "ingredient": { "tag": "c:ingots/steel" },
  "stats": { "damage_multiplier": 1.5 },
  "effects": [
    { "type": "fletcherstrestle:damage_multiplier_if_target_armored",
      "multiplier": 1.25 },
    { "type": "fletcherstrestle:apply_effect",
      "effect": "minecraft:wither",
      "duration": 80,
      "amplifier": 1 }
  ]
}

Pair it with a PNG at assets/mypack/textures/entity/projectiles/head/steel_spike.png and a lang entry "material.mypack.steel_spike": "Steel Spike".

Done. Steel ingots are now a valid head in the fletching menu, the arrow has 1.5× damage, +25% to armored targets, applies Wither II for 4 seconds on hit.

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KubeJS scripts

Use the scripted_callback effect type to hook custom behavior from a KubeJS startup script:

const Callbacks = Java.loadClass(
    'net.frostytrix.fletcherstrestle.material.ScriptedEffectCallbacks');
const RL = Java.loadClass('net.minecraft.resources.ResourceLocation');

Callbacks.register(RL.parse('mypack:wither_on_hit'), {
    onArrowHit: (arrow, hit) => {
        const target = hit.getEntity();
        if (target) target.addEffect(/* … */);
    }
});

Then reference "id": "mypack:wither_on_hit" in any material's effect list.

The handler object can override any of the seven lifecycle hooks (onArrowSpawn, onArrowTick, onPreArrowHit, onArrowHit, onArrowHitBlock, onBowRelease, onProjectileFired).

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Java companion mods (extending the vocabulary)

If your behavior won't fit the existing vocabulary even with scripted_callback, you can register a brand-new MaterialEffectType in a small companion mod:

public static final DeferredRegister<MaterialEffectType<?>> EFFECT_TYPES =
    DeferredRegister.create(
        net.frostytrix.fletcherstrestle.material.ModMaterialEffectTypes.REGISTRY_KEY,
        "mypack");

Your custom effect class implements MaterialEffect, overrides whichever lifecycle hooks it needs, and exposes a MapCodec for JSON parsing. Pack JSONs then reference "type": "mypack:my_effect".

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What's still hardcoded

Five head behaviors retain their Java-side logic because they need stateful coordination with the arrow's tick loop that the simple effect hooks can't express cleanly. They're still reachable — a modpack can add new materials with the same id and the behavior will fire — but the id strings below are reserved keywords:

• glass_vial — potion splash on impact
• resonance_tip — delayed echo damage
• weighted_hook — hook + pull-the-shooter grapple
• trailing_rope — drops a block chain downward from impact
• vex (fletching) — phases through one block of cover
• flax (string) — aim jitter on overdraw

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Sanity checklist

Adding a material to your pack:

1. JSON at data/<pack>/fletcherstrestle/<part>/<id>.json ✓
2. Texture at assets/<pack>/textures/entity/projectiles/<part>/<id>.png ✓
3. Translation key material.<pack>.<id> in your lang file ✓
4. Ingredient (single item / item list / tag) ✓
5. Tag entry in the matching fletcherstrestle:<slot> tag so the fletching menu accepts the input ✓

Full reference in MODPACK_INTEGRATION.md.