Wall

A wall is one straight edge of a sector's outline, from a start point to an end point on the map. Walls aren't drawn separately: they appear automatically when you draw sectors, one for every edge.

What a wall looks like in the game depends on the sectors on its two sides:

Sides	Result
Sector on one side only	A solid wall from that sector's floor to its ceiling.
Sectors on both sides	An opening (a portal) between the two rooms. Solid pieces are drawn only where the two rooms don't overlap in height: a step up, a lintel over a doorway, the face of a raised platform.

So you never make a "doorway wall". You make two sectors with different floor or ceiling heights next to each other, and the wall between them fills in the difference.

Front and back

Every wall has a direction, from start to end. Looking down on the map:

• the front sector is on the left side of that direction;
• the back sector is on the right side;
• normal points toward the front (left) side.

A one-sided wall has only one of them set; the other is invalid (4294967295).

Top, bottom and middle textures

A wall has three textures, Top, Bottom and Middle, each with its own offset, scale, flip and anchor.

• A solid wall (a sector on one side only) shows only Top. The inspector calls it Texture.
• A portal shows Bottom on the step under the neighbouring room's floor, and Top on everything else: the wall above the neighbour's ceiling, and any slab between two of its floors.
• Middle fills a portal's openings, where both rooms are open space: fences, bars, grates, windows. It always fills the whole opening (each one, when stacked floors leave several), follows sloped floors and ceilings, and is one surface seen from both sides. Transparent pixels show through. With no Middle texture there is nothing in the opening at all. Solid walls have no openings, so their Middle fields are greyed out.

A Middle has two switches of its own:

Switch	Default	Effect
Has Collision	on	Blocks entity colliders like a solid wall.
Ignored by Raycast	off	Raycasts pass through it: script raycasts, LineOfSight, and clicking it in the runtime editor.

Anchor

The anchor is the height a texture is pinned to. When a floor or ceiling moves, a texture pinned to the moving edge moves with it; otherwise the edge slides over a texture that stays put.

Anchor	Lua	Pinned to
Auto	WallAnchor.Auto	The top edge, except the wall above a neighbour's ceiling, which uses its bottom edge. Doors and lifts carry their textures with them.
Top Edge	WallAnchor.TopEdge	The piece's top edge.
Bottom Edge	WallAnchor.BottomEdge	The piece's bottom edge.
World	WallAnchor.World	World height 0. The texture never moves; use it for door tracks or to line up neighbouring walls.

The offset is added on top of the anchor. Textures read upright from both sides of a wall.

Collision

Physics tests entity colliders against the solid parts of each wall. An opening is passable as long as the entity fits through the gap, unless it has a Middle texture with Has Collision on. If the solid part in the way is a low step at the entity's feet, and it is no taller than its collider's Step Size, the entity steps up onto it instead of being blocked. See Collider.

In the editor

Field	Lua	Notes
Name		Editor only. Scripts can't read it.
Front Sector / Back Sector	frontSector / backSector	Set by the map topology. Read-only.
Texture (solid) / Top, Bottom (portal)	topTexture, bottomTexture	Texture drawn on the solid parts. Empty means colour only.
Middle (portal)	middleTexture	Texture in the openings. Empty means nothing is there.
Wall Color	color	Tint, Vector4, 0..1 per channel.
UV Offset	topTextureOffset, bottomTextureOffset, middleTextureOffset	Shifts the texture, in map units: 32 moves it by one repeat at scale 1.
UV Scale	topTextureScale, bottomTextureScale, middleTextureScale	How many times the texture repeats. 2.0 means twice as many repeats.
Flip U / Flip V		Mirror the texture horizontally or vertically. Editor only.
Anchor	topAnchor, bottomAnchor, middleAnchor	See Anchor. Auto is the top edge for Middle.
Has Collision / Ignored by Raycast	middleHasCollision, middleIgnoredByRaycast	Middle only. See above.
Tags	HasTag, GetTag, tagCount	Read-only from scripts.

The sector's light also darkens the wall (see Sector).

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Scripting

Getting a wall

Where from	How
A public field	public Wall switchWall
A sector	sector:GetWall(i), i from 1 to sector.wallCount
A raycast hit	hit.wall, when hit.type == "Wall"

A Wall value is a safe handle. If the wall stops existing (the map was edited), isValid becomes false and any other use raises an error. sector:GetWall(i) can also return an invalid wall, so check isValid.

Properties

Property	Type		Description
id	integer	read-only	Stable wall ID.
isValid	boolean	read-only	false if the wall no longer exists.
start	Vector2	read-only	Start point (x, z).
end	Vector2	read-only	End point (x, z). end is a Lua keyword, so write wall["end"].
dir	Vector2	read-only	Unit vector from start to end.
normal	Vector2	read-only	Unit vector perpendicular to the wall, pointing to the front side.
length	number	read-only	Length in map units.
frontSector	integer	read-only	ID of the front sector.
backSector	integer	read-only	ID of the back sector.
isPortal	boolean	read-only	true if there is a sector on both sides, so bottomTexture can show.
color	Vector4	read/write	Tint, 0..1.
topTexture	string	read/write	Top texture path relative to Assets, e.g. "Textures/brick.png".
bottomTexture	string	read/write	Bottom texture path. Only shows on a portal.
topTextureOffset	Vector2	read/write	Top texture shift in map units. Change it over time to scroll.
bottomTextureOffset	Vector2	read/write	Bottom texture shift in map units.
topTextureScale	Vector2	read/write	Top texture repeats per 32 map units.
bottomTextureScale	Vector2	read/write	Bottom texture repeats per 32 map units.
topAnchor	WallAnchor	read/write	Where the top texture is pinned, e.g. WallAnchor.World.
bottomAnchor	WallAnchor	read/write	Where the bottom texture is pinned.
middleTexture	string	read/write	Middle texture path, filling the openings. "" means no middle.
middleTextureOffset	Vector2	read/write	Middle texture shift in map units.
middleTextureScale	Vector2	read/write	Middle texture repeats per 32 map units.
middleAnchor	WallAnchor	read/write	Where the middle texture is pinned.
middleHasCollision	boolean	read/write	The middle blocks entity colliders.
middleIgnoredByRaycast	boolean	read/write	Raycasts and LineOfSight pass through the middle.
tagCount	integer	read-only

Methods

Method	Returns	Description
ClearTopTexture()		Removes the top texture.
ClearBottomTexture()		Removes the bottom texture.
ClearMiddleTexture()		Removes the middle texture, and with it the middle.
HasTag(tag)	boolean	true if the wall has tag.
GetTag(index)	string	The index-th tag, 1-based.

Any image in Assets can be switched to. When the level loads, the engine packs every .png, .jpg and .jpeg file under Assets into the texture atlas, so a script can switch to an image the level doesn't use yet. An image added to Assets while the game is running is only picked up the next time the level loads.

Getting the sector on each side

frontSector and backSector are IDs, not Sector values. To get the sector itself, look up a point just off the wall's middle:

local function SideSector(wall, side)  -- side = 1 for front, -1 for back
    local s, e = wall.start, wall["end"]
    local mid = Vector2((s.x + e.x) * 0.5, (s.y + e.y) * 0.5)
    return Game.GetSectorAt(mid + wall.normal * (0.5 * side))
end

In a sector script, the neighbour behind a wall is also in sector:GetNeighbor(i).

Walls have no callbacks

Walls can't hold scripts. To react to a wall, use a sector script on one of its sectors, or a raycast from an entity script.

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Examples

Scrolling texture

-- Scripts/Walls/Scroll.lua (sector script)
-- Scrolls every wall of this sector that has the "conveyor" tag.
public Vector2 speed = Vector2(0.5, 0)

local walls = {}

function Start()
    for i = 1, sector.wallCount do
        local wall = sector:GetWall(i)
        if wall.isValid and wall:HasTag("conveyor") then walls[#walls + 1] = wall end
    end
end

function Update()
    local step = speed * GameTime.deltaTime
    for _, wall in ipairs(walls) do
        wall.topTextureOffset = wall.topTextureOffset + step
    end
end

Switch that changes texture when used

-- Scripts/Walls/WallSwitch.lua (on the player)
-- Look at a wall tagged "switch" and press E to flip it.
public number reach = 48
public Texture onTexture = nil
public Sector door = nil

function Update()
    if not Input.GetKeyDown(Key.E) then return end

    local camera = entity.camera
    if camera == nil then return end

    local hit = camera:Raycast(reach, false)

    if hit == nil or hit.wall == nil or not hit.wall:HasTag("switch") then return end

    -- An unassigned Texture field is an empty string, not nil.
    if onTexture ~= nil and onTexture ~= "" then hit.wall.topTexture = onTexture end
    if door ~= nil then door:MoveCeilingTo(1, door.floorHeight + 40, 60) end
end

Flash every wall in a room

-- Scripts/Walls/Alarm.lua (sector script)
public Vector4 flashColor = Vector4(1, 0.2, 0.2, 1)

local walls = {}
local original = {}
local t = 0

function Start()
    for i = 1, sector.wallCount do
        local wall = sector:GetWall(i)
        if wall.isValid then
            walls[#walls + 1] = wall
            original[#original + 1] = wall.color
        end
    end
end

function Update()
    t = t + GameTime.deltaTime
    local k = (mathT.Sin(t * 6) + 1) * 0.5

    for i, wall in ipairs(walls) do
        wall.color = mathT.Vector4Lerp(original[i], flashColor, k)
    end
end