Surface and Brush Reference

This page is the quick reference for what Grid Placement 6.0 places and paints.

Surface support

Surface	6.0 support	Notes
2D `TileMapLayer` objects	Supported	Preview, validation, commit, manipulation, demolition, and optional object `LINE` placement.
2D `TileMapLayer` terrain	Supported	`SINGLE`, `LINE`, `RECTANGLE_FILL`, `RECTANGLE_OUTLINE`, and `FLOOD_FILL`.
Isometric 2D	Supported	Uses the same `TileMapLayer` placement model; verify project-specific tile transforms and visuals.
Hex 2D	Supported advanced workflow	Shipped demo covers multi-cell terrain brushes on the included hex setup.
3D `GridMap` GRID objects	Supported	CELL, EDGE, FACE/socket, footprints, yaw, validation, manipulation, persistence, and configurable slope/support.
3D SMOOTH objects	Supported	Free world-space placement with occupancy/validation and optional world-space sockets.
3D `GridMap` terrain editing	Not supported	2D terrain brush claims do not apply to 3D.
Terrain-conforming structural pitch/roll	Not supported by default	GRID structures remain world-up; slope/support controls whether placement is allowed.

Shipped demos

Grid Placement 6.0 ships five reference demos:

Demo	Primary purpose
Top-down 2D	Basic object placement, terrain painting, manipulation, and persistence.
Isometric 2D	Isometric targeting and placement presentation.
Platformer 2D	Placement/validation in a side-view collision-driven scene.
Hex 2D	Advanced terrain brush behavior on a hex layout.
3D	GRID/SMOOTH object placement, CELL/EDGE/FACE/socket structures, slope/support, and persistence.

Demos show supported workflows; they are not required scene architecture for your game.

2D brush modes

Mode	Terrain painting	Object placement	Commit behavior
`SINGLE`	Supported	Supported	Preview one target; confirm commits one terrain cell/object.
`LINE`	Supported	Opt-in by profile/category	Drag start→end; final validation runs before commit.
`RECTANGLE_FILL`	Supported	Not a public object mode	Drag two corners; commit fills the generated terrain region.
`RECTANGLE_OUTLINE`	Supported	Not a public object mode	Drag two corners; commit paints the perimeter.
`FLOOD_FILL`	Supported	Not an object mode	Anchor/preview the region, then confirm to commit.

Commit rules

Preview never mutates the real TileMapLayer.
Final validation runs at commit time; the world may have changed since preview.
Cancel clears pending brush/placement state without committing it.
Object LINE placement is explicit capability, not something every ScenePlacementEntry automatically supports.

Terrain brush cell cap

PlacementSettings.max_terrain_brush_cells limits the generated cells for one terrain brush action.

Setting	Value
Default	`4096` cells
Inspector range	`1..16384`
Runtime hard ceiling	`16384` cells
Applies to	`LINE`, `RECTANGLE_FILL`, `RECTANGLE_OUTLINE`, `FLOOD_FILL`

If a large drag/flood operation stops earlier than expected, check this setting before debugging terrain rules.

3D support rules

3D is object placement, not terrain editing.

GRID placement can validate the support under a footprint using GridMap surface information and, when configured, physics-backed sampling. The final support policy can include maximum slope, support coverage, center/edge requirements, and per-entry overrides. Structural pieces remain world-up even when the supporting terrain is sloped.

SMOOTH placement uses world-space transforms rather than CELL/EDGE/FACE grid keys. Optional world-space sockets can provide object-to-object joins without turning them into GRID mounts.

See 3D Object Placement, 3D Surface & Slope Support, and Grid vs Smooth Placement.

First integration path

Install/enable the addon and default input actions.
Place one object successfully.
For 2D terrain, add one terrain entry and prove SINGLE before multi-cell brushes.
Add manipulation/persistence/custom rules after the core path works.
For 3D, prove GRID placement before adding mounts, SMOOTH sockets, or custom support policy.