t1k:unity:editor:dots-inventory-grid

Field	Value
Module	`editor`
Version	`2.1.7`
Effort	`high`
Tools	—

Keywords: DOTS, grid, inventory, UI

How to invoke

/t1k:unity:editor:dots-inventory-grid

DOTS Inventory Grid, Passives & Set Bonuses

Extensions to com.the1studio.dots-inventory Inventory module. Base module (slots, equipment, loot, currency, crafting) → See dots-rpg skill references/inventory-guide.md.

Related skills: dots-rpg · dots-ecs · dots-jobs-burst

When This Skill Triggers

Adding InventoryGridDimension, InventoryGridCell, ItemGridShape, ItemGridPosition, ItemRotation
Calling InventoryGridUtility.CanPlace, .PlaceItem, .FindFirstFit, .GetEffectiveDimensions
Using expansion APIs: CanPlaceExpansion, ActivateCells, IsAdjacentToActive, CountActiveCells
Adding ItemPassiveEffect buffer to items; using PassiveCondition.InInventory or .EquippedOnly
Adding ItemSetMembership, SetBonusDefinition; implementing set threshold rewards
Using ModifierSource.ItemPassive or ModifierSource.ItemSet in stat modifier logic

Component Quick Reference

Grid Layer

Component	Type	Fields	Owner
`InventoryGridDimension`	IComponentData	`int GridWidth, GridHeight`	Character — opt-in gate
`InventoryGridCell`	IBufferElementData	`Entity ItemEntity, byte IsActive`	Character — W×H flat array
`ItemGridShape`	IComponentData	`int DefaultWidth, DefaultHeight`	Item entity
`ItemGridPosition`	IComponentData	`int GridX, GridY`	Item entity — (-1,-1) = unplaced
`ItemRotation`	IComponentData	`byte RotationIndex`	Item entity — 0..3
`ItemNoRotationTag`	IComponentData (zero-size)	—	Item — prevents rotation
`ItemLockedTag`	IComponentData (zero-size)	—	Item — prevents movement
`ItemShapeMask`	IBufferElementData	`int2 Offset`	Item — polyomino shape (opt-in)

Passive Layer

Component	Type	Fields	Owner
`ItemPassiveEffect`	IBufferElementData	`StatType, ModifierType, float Value, PassiveCondition`	Item entity

PassiveCondition enum: InInventory (always active) · EquippedOnly (only when in EquippedItem buffer)

Set Bonus Layer

Component	Type	Fields	Owner
`ItemSetMembership`	IComponentData	`int SetId`	Item entity
`SetBonusDefinition`	IBufferElementData	`int SetId, int RequiredCount, StatType, ModifierType, float Value`	World singleton

System Ordering (InventorySystemGroup)

RespawnReset (OrderFirst)
  → PickupSystem
    → GridPlacementSystem      [UpdateAfter(Pickup), UpdateBefore(Equipment)]
    → ItemSetBonusSystem       [UpdateAfter(Pickup), UpdateBefore(Equipment)]
    → PassiveEffectSystem      [UpdateAfter(Pickup), UpdateBefore(Equipment)]
    → EquipmentSystem
  → Crafting / Currency
  → LootDrop (OrderLast)

All three new systems share the EquipmentDirtyTag gate. GridPlacementSystem does not disable the tag — downstream systems still need it. ItemSetBonusSystem additionally uses RequireForUpdate<SetBonusDefinition>.

→ See references/grid-placement-guide.md for InventoryGridUtility API. → See references/passive-effects-guide.md for clear-and-rebuild pattern. → See references/set-bonuses-guide.md for threshold stacking. → See references/gotchas.md for all critical gotchas.

Quick Examples

Auto-place item on pickup (done by GridPlacementSystem; manual trigger):

var cells = SystemAPI.GetBuffer<InventoryGridCell>(owner);
var dim = SystemAPI.GetComponent<InventoryGridDimension>(owner);
var effDim = InventoryGridUtility.GetEffectiveDimensions(shape, rotation);
if (InventoryGridUtility.FindFirstFit(cells, dim.GridWidth, dim.GridHeight,
        effDim.x, effDim.y, out int gx, out int gy))
    InventoryGridUtility.PlaceItem(cells, dim.GridWidth, gx, gy,
        effDim.x, effDim.y, itemEntity);

Add passive effect to item at bake time:

var passives = AddBuffer<ItemPassiveEffect>(item);
passives.Add(new ItemPassiveEffect
{
    Stat = StatType.PhysAtk, ModType = ModifierType.Flat,
    Value = 25f, Condition = PassiveCondition.InInventory
});

Configure set bonus singleton:

var defs = AddBuffer<SetBonusDefinition>(singleton);
// 2-piece bonus
defs.Add(new SetBonusDefinition { SetId = 1, RequiredCount = 2,
    Stat = StatType.CritRate, ModType = ModifierType.PercentAdd, Value = 0.05f });
// 4-piece bonus (stacks WITH 2-piece if 4 items owned)
defs.Add(new SetBonusDefinition { SetId = 1, RequiredCount = 4,
    Stat = StatType.PhysAtk, ModType = ModifierType.PercentMul, Value = 0.20f });

→ See references/demo-shapes-guide.md for ModifierSource separation table.

Reference Files

File	Content
grid-placement-guide.md	InventoryGridUtility API, rotation rules, auto-placement algorithm
passive-effects-guide.md	PassiveCondition, clear-and-rebuild pattern, bake setup
set-bonuses-guide.md	SetBonusDefinition config, counting logic, threshold stacking
gotchas.md	G1-G10, G14 — core gotchas
gotchas-ui-drag.md	G11-G13 — UI drag-and-drop gotchas
demo-shapes-guide.md	Polyomino shapes API, InventoryDemo, ModifierSource separation
library-api.md	DOTSInventory.Loot.RarityRoller — Burst-safe weighted rarity roll with pity

rules/library-feature-discovery-protocol.md — research the library 3× before implementing new functionality; always update this skill with what you find (or with the new code if you implement it)
rules/manual-correction-implies-skill-gap-unity.md — if you manually inject library/API knowledge into a teammate brief, that knowledge belongs in this skill, not the brief