hey basically im working on a fortnite building system

but i have a problem which is the incrementing of the grid placement system

local self = setmetatable({}, {__index = {}})

local Player = game.Players.LocalPlayer
local Mouse = Player:GetMouse()

local function CurrentModel(model)
    local cloned = model:Clone()
    cloned.Parent = workspace
	cloned.Hitbox.Transparency = .75
    return cloned
end

local RunService = game:GetService("RunService")

local part = CurrentModel(game.ReplicatedStorage["Project Royale Build Models"].Wall)

Mouse.TargetFilter = part

local RoundTo = 18

function grid(x)
    return math.floor((x / RoundTo) + 0.5) * RoundTo
end

function NotColliding(part)
	local region = Region3.new(
        part.PrimaryPart.Position - (part.PrimaryPart.Size * 0.45),
        part.PrimaryPart.Position + (part.PrimaryPart.Size * 0.45)
    )
    local tab = workspace:FindPartsInRegion3WithIgnoreList(region, {workspace.Baseplate,workspace.Terrain, unpack(part:GetChildren())})
    if #tab == 0 then
        return true
	else
        return false
    end
end

function Place(part)
	if not NotColliding(part) then return end
    local Clone = part:Clone()
	Clone.Hitbox.BrickColor = BrickColor.new("Linen")
	Clone.Parent = workspace
	Clone.Hitbox.Transparency = 0
	Clone.Hitbox.CanCollide = true
end

Mouse.Button1Down:Connect(function()
    Place(part)
end)

game:GetService("UserInputService").InputBegan:Connect(function(Input, gp)
	if Input.KeyCode == Enum.KeyCode.Q then
		part:Destroy()
		part = CurrentModel(game.ReplicatedStorage["Project Royale Build Models"].Wall)
	elseif Input.KeyCode == Enum.KeyCode.E then
		part:Destroy()
		part = CurrentModel(game.ReplicatedStorage["Project Royale Build Models"].Floor)
	elseif Input.KeyCode == Enum.KeyCode.Z then
		part:Destroy()
		part = CurrentModel(game.ReplicatedStorage["Project Royale Build Models"].Ramp)
	end
end)

RunService.RenderStepped:Connect(function()
    local targetPosition = Mouse.Hit.Position + Vector3.new(0, part.PrimaryPart.Size.Y * 0.5, 0)
    local X = grid(targetPosition.X)
    local Y = grid(targetPosition.Y)
    local Z = grid(targetPosition.Z)
	local IsColliding = not NotColliding(part)
	if IsColliding then
		part.Hitbox.BrickColor = BrickColor.new("Really red")
	else
		part.Hitbox.BrickColor = BrickColor.new("Linen")
	end
	local lookVec = Player.Character:GetPrimaryPartCFrame().LookVector
    local a = math.atan2(-lookVec.X, -lookVec.Z)
    part.PrimaryPart.CFrame = Player.Character:GetPrimaryPartCFrame() * CFrame.new(0, 0, -5) * CFrame.Angles(0, math.rad(math.floor((math.deg(a) / 90) + 0.5) * 90), 0)
	part.PrimaryPart.CFrame = CFrame.new(X,Y,Z, part.PrimaryPart.CFrame.RightVector.X,part.PrimaryPart.CFrame.RightVector.Y,part.PrimaryPart.CFrame.RightVector.Z,part.PrimaryPart.CFrame.UpVector.X,part.PrimaryPart.CFrame.UpVector.Y,part.PrimaryPart.CFrame.UpVector.Z,part.PrimaryPart.CFrame.LookVector.X,part.PrimaryPart.CFrame.LookVector.Y,part.PrimaryPart.CFrame.LookVector.Z)
	part.PrimaryPart.Orientation = Vector3.new(0,(math.floor((math.deg(a) / 90) + 0.5) * 90),0)
end)

I have bad understanding of math and if u can fix this issue plz do so.

Anonymous