Coloring connecting walls together

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1

I’m trying to color connecting walls to match as they get created. Basically, I have nodes on a grid, grouped together

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image164×217 4.65 KB

I generate line segments between A-B
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image1044×425 51.9 KB

as you can see each line generates a left and right line. I want to calculate that its connecting at a node, and calculate the connecting lines, to color them accordingly. My code atm just colors the same segments together (I don’t want that)

This is what it SHOULD look like

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image528×404 26.9 KB

local Nodes = workspace:WaitForChild("Nodes")
local WALL_OFFSET = 0.45
local WALL_THICKNESS = 0.05
local WALL_HEIGHT = 14

-- Global state for unique coloring
local globalColorIndex = 1

local function VecKey(vec)
	return string.format("%.3f,%.3f", vec.X, vec.Z)
end

local function CreateWallPart(startPos, endPos, sideOffset, name)
	local Direction = (endPos - startPos)
	local Length = Direction.Magnitude
	local MidPoint = (startPos + endPos) / 2
	local LookCFrame = CFrame.lookAt(MidPoint, endPos, Vector3.yAxis)
	local Offset = LookCFrame.RightVector * sideOffset

	local Part = Instance.new("Part")
	Part.Name = name
	Part.Size = Vector3.new(WALL_THICKNESS, WALL_HEIGHT, Length)
	Part.Anchored = true
	Part.CanCollide = true
	Part.TopSurface = Enum.SurfaceType.Smooth
	Part.BottomSurface = Enum.SurfaceType.Smooth
	Part.CFrame = LookCFrame + Offset

	return Part, LookCFrame.LookVector, Offset
end

local function SignedAngle2D(a: Vector3, b: Vector3): number
	local dot = a.X * b.X + a.Z * b.Z
	local det = a.X * b.Z - a.Z * b.X
	return math.deg(math.atan2(det, dot))
end

local function GetUniqueColor(index)
	local palette = {
		Color3.fromRGB(255, 0, 0), Color3.fromRGB(0, 0, 255), Color3.fromRGB(0, 255, 0),
		Color3.fromRGB(255, 255, 0), Color3.fromRGB(255, 0, 255), Color3.fromRGB(0, 255, 255),
		Color3.fromRGB(128, 0, 128), Color3.fromRGB(255, 165, 0), Color3.fromRGB(165, 42, 42),
		Color3.fromRGB(75, 0, 130)
	}
	return palette[(index - 1) % #palette + 1]
end

local Segments = {}
local NodeConnections = {}

local function AddToNodeMap(key, segment)
	NodeConnections[key] = NodeConnections[key] or {}
	table.insert(NodeConnections[key], segment)
end

local PartToColorIndex = {}
local ColorIndexToColor = {}

local function TryAssignColorToPart(part, nodeKey, basePos)
	local dir = (part.Position - basePos).Unit
	local angle = math.atan2(dir.Z, dir.X)

	local bestMatch = nil
	local bestAngleDiff = math.huge

	local connections = NodeConnections[nodeKey]
	if not connections then return end

	for _, seg in ipairs(connections) do
		local candidates = {seg.Left, seg.Right}

		for _, otherPart in ipairs(candidates) do
			if otherPart == part then continue end
			if not otherPart:IsDescendantOf(workspace) then continue end

			local otherBase = (seg.StartKey == nodeKey) and seg.StartPos or seg.EndPos
			local otherDir = (otherPart.Position - otherBase).Unit
			local otherAngle = math.atan2(otherDir.Z, otherDir.X)

			local diff = math.abs(math.atan2(math.sin(angle - otherAngle), math.cos(angle - otherAngle)))
			if diff < bestAngleDiff then
				bestAngleDiff = diff
				bestMatch = otherPart
			end
		end
	end

	if bestMatch and PartToColorIndex[bestMatch] then
		local colorIndex = PartToColorIndex[bestMatch]
		part.Color = ColorIndexToColor[colorIndex]
		PartToColorIndex[part] = colorIndex
	else
		-- New color
		local newIndex = globalColorIndex
		globalColorIndex += 1
		local color = GetUniqueColor(newIndex)
		part.Color = color
		PartToColorIndex[part] = newIndex
		ColorIndexToColor[newIndex] = color
	end
end

for _, Node in ipairs(Nodes:GetChildren()) do
	local A = Node:FindFirstChild("A")
	local B = Node:FindFirstChild("B")
	if not (A and B and A:IsA("BasePart") and B:IsA("BasePart")) then continue end

	local APos, BPos = A.Position, B.Position
	local AKey, BKey = VecKey(APos), VecKey(BPos)
	local Dir = (BPos - APos).Unit

	local WallModel = Instance.new("Model")
	WallModel.Name = Node.Name .. "_Wall"
	WallModel.Parent = Node

	local Left, _, _ = CreateWallPart(APos, BPos, -WALL_OFFSET / 2, "Left")
	local Right, _, _ = CreateWallPart(APos, BPos, WALL_OFFSET / 2, "Right")
	Left.Parent = WallModel
	Right.Parent = WallModel

	local Segment = {
		StartPos = APos,
		EndPos = BPos,
		StartKey = AKey,
		EndKey = BKey,
		Dir = Dir,
		Left = Left,
		Right = Right,
		Model = WallModel,
	}
	table.insert(Segments, Segment)
	AddToNodeMap(AKey, Segment)
	AddToNodeMap(BKey, Segment)

	TryAssignColorToPart(Left, AKey, APos)
	TryAssignColorToPart(Right, BKey, BPos)

	task.wait()
end
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