08 - Walls and Textures

A sector script can reach every wall of its sector:

for i = 1, sector.wallCount do
    local wall = sector:GetWall(i)   -- a Wall
    if wall.isValid then             -- always check, some slots can be empty
        Debug.Print("wall", wall.id, "is", wall.length, "units long")
    end
end

Useful Wall members:

Member	Type	Notes
wall.color	Vector4	Tint, 0..1 per channel (r, g, b, a)
wall.topTextureOffset, wall.bottomTextureOffset, wall.middleTextureOffset	Vector2	Scrolls a texture. Change it over time for moving surfaces
wall.topTexture, wall.bottomTexture, wall.middleTexture	string	Swap a texture. wall:ClearTopTexture() / wall:ClearBottomTexture() / wall:ClearMiddleTexture() remove it
wall.topAnchor, wall.bottomAnchor, wall.middleAnchor	WallAnchor	Where a texture is pinned (Auto, TopEdge, BottomEdge, World)
wall.isPortal	boolean	true if a sector is on both sides. Bottom and Middle only show on portals
wall.middleHasCollision, wall.middleIgnoredByRaycast	boolean	Whether the middle (fence, bars) blocks movement, and whether raycasts pass through it
wall.start, wall["end"], wall.length	read-only	Endpoints (Vector2) and length. end is a Lua keyword, so use wall["end"]
wall.frontSector, wall.backSector	integer IDs	backSector identifies the neighbour on a portal wall
wall:HasTag("Name")	boolean	Tags are assigned in the editor

Tags are the easiest way to say which walls a script should touch. Create a tag in the project settings, put it on the walls, and filter with wall:HasTag(...).

---

Scrolling texture

Attach to: the sector whose walls should scroll: a waterfall, a conveyor belt, lava.

-- Scripts/Walls/ScrollingWall.lua (sector script)
public number scrollX = 0.0
public number scrollY = 0.25
public string onlyTag = ""

local walls = {}

function Start()
    for i = 1, sector.wallCount do
        local wall = sector:GetWall(i)

        if wall.isValid and (onlyTag == "" or wall:HasTag(onlyTag)) then
            walls[#walls + 1] = wall
        end
    end
end

function Update()
    local dt = GameTime.deltaTime

    for _, wall in ipairs(walls) do
        local offset = wall.topTextureOffset
        wall.topTextureOffset = Vector2(offset.x + scrollX * dt, offset.y + scrollY * dt)
    end
end

Notes

• Walls are looked up once in Start and kept in a table, so Update doesn't have to search the sector every frame.
• Set onlyTag to something like Scroll to animate only some walls of the sector.

---

Texture switch (press to change a wall's texture)

Attach to: the sector containing a wall tagged Switch.

Looks at the wall and presses a key to flip it between an "off" and an "on" texture. It uses camera:Raycast from the camera to see which wall is being looked at.

-- Scripts/Walls/TextureSwitch.lua (sector script)
public Entity player = nil
public string switchTag = "Switch"
public Texture offTexture = nil
public Texture onTexture = nil
public Key useKey = Key.E
public number useDistance = 40

local switches = {}   -- wall -> on/off

function Start()
    if player == nil then
        Debug.LogWarning("TextureSwitch in sector " .. sector.id .. " has no player assigned")
        return
    end

    for i = 1, sector.wallCount do
        local wall = sector:GetWall(i)

        if wall.isValid and wall:HasTag(switchTag) then
            switches[#switches + 1] = { wall = wall, on = false }
        end
    end
end

function Update()
    if player == nil or not player.isValid or #switches == 0 then return end
    if not Input.GetKeyDown(useKey) then return end

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

    -- Cast a ray from the player's eyes through the middle of the screen.
    local hit = camera:Raycast(useDistance, false)
    if hit == nil or hit.type ~= "Wall" then return end

    for _, s in ipairs(switches) do
        if s.wall.id == hit.wallID then
            s.on = not s.on

            local texture = s.on and onTexture or offTexture
            if texture ~= nil then s.wall.topTexture = texture end

            Debug.Print("Switch is now " .. (s.on and "ON" or "OFF"))
            return
        end
    end
end

Notes

• hit.wallID is the ID of the wall the ray struck, which is compared to each switch wall's id.
• The fifth argument to Raycast (false) means entities don't need a collider to be hit. Walls are always hit.
• Texture fields (Texture) hold the asset's path, which can be assigned directly to wall.topTexture or wall.bottomTexture.
• To make the switch do something, set a channel from 05_doors.md right where s.on changes: Global.channels = Global.channels or {} then Global.channels["door1"] = s.on.

---

Color cycling

Attach to: a sector with walls that should shimmer, like a disco room.

Cycles the tint of walls through the rainbow with three phase-shifted sine waves.

-- Scripts/Walls/ColorCycle.lua (sector script)
public number cyclesPerSecond = 0.25
public string onlyTag = ""

local walls = {}
local clock = 0.0

function Start()
    for i = 1, sector.wallCount do
        local wall = sector:GetWall(i)

        if wall.isValid and (onlyTag == "" or wall:HasTag(onlyTag)) then
            walls[#walls + 1] = wall
        end
    end
end

function Update()
    clock = clock + GameTime.deltaTime * cyclesPerSecond * 2 * math.pi

    -- Three sine waves 120 degrees apart, remapped from -1..1 to 0..1.
    local r = 0.5 + 0.5 * math.sin(clock)
    local g = 0.5 + 0.5 * math.sin(clock + 2.094)
    local b = 0.5 + 0.5 * math.sin(clock + 4.188)

    for _, wall in ipairs(walls) do
        local current = wall.color
        wall.color = Vector4(r, g, b, current.w)   -- keep each wall's own alpha
    end
end