PlacementSystem | Grid Placement Docs

Draft — Unreleased:This page is in active development. APIs, class names, and behavior may change before the release is finalized. Use it as a preview of what's coming — not as a stable integration target.

Manages placement of objects in the game world. Handles preview, placement validation, and placement actions. Uses tile collision indicators to show valid/invalid spots before placement. Checks all rules before adding objects to the world and emits signals for placement success or failure. @deprecated Will be removed in 6.1. Add a GridPlacementHost to your scene, set a PlacementSession on a GridPositioner2D, and the positioner will register the session with the host. The host owns runtime input. See the 6.0 migration guide for the path.

Source: addons/grid_placement/systems/building/placement_system.gd

Syntax

class PlacementSystem extends PlacementSystemBase

Members

Name	Kind	Summary
`PlaceMode`	Field	Explicit build mode for the building system (5.2+) NONE: No build mode active OBJECT: Placing scene objects via ScenePlacementEntry resources TERRAIN: Painting terrain tiles by terrain name, resolved against the TileSet SSOT DECORATION: Kept for backward compatibility but aliases OBJECT Canonical name for the placement mode enum. Use [PlaceMode.OBJECT] etc. in new code — `BuildMode` is kept as a backward-compatible alias for the same enum (the names are interchangeable; values are identical).
`build_mode_changed`	Event	Router-facing submode inside global PLACE mode. NONE means the user is in PLACE but has not chosen terrain or objects yet. Emitted when the build mode changes
`place_submode_changed`	Event	Emitted when the router-facing place submode changes (see PlaceSubmode).
`create_with_injection`	Method
`system`	Property
`issues`	Property
`logger`	Property
`create_with_session`	Method
`system`	Property
`issues`	Property
`placement_polygons`	Property	Collision polygons for placement indicators.
`preview_layer`	Property	Preview layer index for buildable/unbuildable tiles.
`selected_placeable`	Property	Currently selected placeable resource. Proxy to [member PlacementSession.selected_placeable] when wired through a [PlacementContainer]. Reads and writes both legs so legacy scenes and session-built variants behave identically. The session is the canonical home: writes trigger [signal PlacementSession.placeable_selected] which the host observes in [method GridPlacementHost.configure]. The backup backing field handles tests/legacy paths that run without a [PlacementContainer]. This closes the terrain/object cross-leak where a smithy pick persisted into a fence placement because the system field was the divergent source — the band-aid revert target.
`selected_terrain_name`	Property	Currently selected terrain name (new path). Empty when no terrain is selected. Resolved against the target TileMapLayer's TileSet at paint-time. Proxy to [member PlacementSession.selected_terrain_name] when wired through a [PlacementContainer], else falls back to [member _selected_terrain_name_backing]. Symmetric to [member selected_placeable] — also closes the dual-write band-aid where the system wrote to both itself and the session on every select.
`selected_terrain_entry`	Property	The currently selected terrain entry (if any).
`selected_terrain_palette`	Property	The currently selected terrain palette (if any).
`current_mode`	Property	Current explicit build mode (5.2+) Computed from [member _place_machine].
`current_place_submode`	Property	Current router-facing submode inside global PLACE mode. Computed from [member _place_machine].
`brush_state`	Property	Brush state accessor (read-only). The actual [BrushState] is owned by [member _brush_coordinator] (P4 god-class extraction); this property preserves the public test-facing API that pre-existed the extraction so test code can still read `building_system.brush_state` to introspect drag/pending state. Returns null if the coordinator has not been constructed yet (e.g. before [method resolve_placement_dependencies]).
`indicators_group`	Property	Parent node for collision indicators.
`get_building_state`	Method
`get_targeting_state`	Method
`get_states`	Method
`get_logger`	Method
`set_logger`	Method
`get_actions`	Method
`get_indicator_context`	Method
`set_states`	Method
`set_actions`	Method
`set_indicator_context`	Method
`WARNING_INVALID_PLACEABLE`	Field
`WARNING_NO_PREVIEW`	Field
`is_ready_to_place`	Method
`r_ctx`	Property
`is_ready_to_paint_terrain`	Method
`r_ctx`	Property
`get_terrain_preview_cells`	Method
`host_cells`	Property
`positioner`	Property
`current_cell`	Property
`get_host_terrain_preview_cells`	Method
`host_brush`	Property
`positioner`	Property
`current_cell`	Property
`report`	Property
`try_place_terrain_brush`	Method
`target_map`	Property
`positioner`	Property
`cell`	Property
`report`	Property
`target_map`	Property
`report`	Property
`positioner`	Property
`report`	Property
`current_cell`	Property
`cells`	Property
`report`	Property
`placed_count`	Property
`skipped_count`	Property
`skipped_reasons`	Property
`MAX_SKIPPED_REASONS`	Field
`world_pos`	Property
`cell_report`	Property
`issues`	Property
`report`	Property
`summary_report`	Property
`set_brush_shape`	Method
`exit_build_mode`	Method
`get_terrain_service`	Method
`get_terrain_context`	Method
`set_host`	Method
`get_host`	Method
`get_manipulation_service`	Method
`manip_settings`	Property
`get_grid_targeting_service`	Method
`enter_place_router`	Method
`set_place_submode`	Method
`resolve_placement_dependencies`	Method
`settings`	Property
`settings`	Property

Source

addons/grid_placement/systems/building/placement_system.gd

Plugin docs root:gdscript/plugins/grid_placement_dev/docs