Grid placement system allignment issue

Help and Feedback Scripting Support
#1

I’m trying to make a grid base placement system, each ‘cell’ is 12x12 studs and the building models’ sizes are dynamic.
So 12x12 studs, fitting perfectly in 1 cell. Or 12x24, where it needs 2 cells in width, and that is where my problem is. I can’t get my head over the allignment if the object is larger than 1 cell, where i could just center it to the grid cell.

I got the allignment correct in one of the axis with the larger model, as you can see in the video


(https://i.gyazo.com/2e00b5c3d20e8e5878e9157402e93d8d.mp4)

Here is my code; (the ‘P’ parts are for visualization)

local function PreviewBuildingPlace(Model)
	if BuidlingPreviewClone then BuidlingPreviewClone:Destroy() end
	if BuildingPreviewConnection then BuildingPreviewConnection:Disconnect() BuildingPreviewConnection = nil end

	BuidlingPreviewClone = workspace[Model]:Clone()
	local highlight = script.PlaceHighlight:Clone()
	highlight.Parent = BuidlingPreviewClone
	Mouse.TargetFilter = BuidlingPreviewClone
	BuidlingPreviewClone.Parent = workspace

	BuildingPreviewConnection = RunService.RenderStepped:Connect(function()
		local MouseHit = Mouse.hit
		local Increment = GridIncrement
		local ObjectSize = BuidlingPreviewClone:GetExtentsSize()

		local NearestX = math.floor(MouseHit.X / Increment) * Increment
		local NearestZ = math.floor(MouseHit.Z / Increment) * Increment

		local adjustedSizeX = math.floor(ObjectSize.X)
		local adjustedSizeZ = math.floor(ObjectSize.Z) 

		local numGridX = math.ceil(adjustedSizeX / Increment)
		local numGridZ = math.ceil(adjustedSizeZ / Increment)
		print(adjustedSizeZ / Increment)
		warn(numGridX, numGridZ)
		
		local CenterX = NearestX + (Increment / 2 * numGridX)
		local CenterZ = NearestZ + (Increment / 2 * numGridZ)



		P4.Position = Vector3.new(CenterX, 1, CenterZ)
		
		local ModelPivot = BuidlingPreviewClone:GetPivot()



		local NewPosition = Vector3.new(
			CenterX,
			ObjectSize.Y / 2,
			CenterZ
		)

		BuidlingPreviewClone:PivotTo(CFrame.new(NewPosition) * CFrame.Angles(0, math.rad(PreviewYRot), 0))
	end)
end

All help is appreciated!