Raycasting Question

Help and Feedback Scripting Support
#1

Hey! I’m trying to learn raycasting to later on build a sandbox build system. I stole some code from a model and it miraculously worked, could anyone tell me why? It’s something to do with workspace.CurrentCamera:ScreenPointToRay(mouse.X, mouse.Y, 1) instead of what I previously had of mouse.Origin.Position. So here are my questions:

  1. How does workspace.CurrentCamera:ScreenPointToRay() work?
  2. This is kind of random but, how would you lock the part position to a grid, like say 2x2 studs?
  3. Is there a better way to achieve what I’m doing?

Here is my full code:

local runService = game:GetService("RunService")
local repStorage = game:GetService("ReplicatedStorage")
local players = game:GetService("Players")

local player = players.LocalPlayer
local mouse = player:GetMouse()

local ground = workspace.Ground

local buttonPressed = false

runService.RenderStepped:Connect(function()
	if buttonPressed then
		local target = mouse.Hit.Position
		local unit = workspace.CurrentCamera:ScreenPointToRay(mouse.X, mouse.Y, 1)
		local raycastResults = workspace:Raycast(unit.Origin, unit.Direction*10000)--workspace:Raycast(origin, distance)
		
		print(raycastResults)
		
		if raycastResults.Instance and raycastResults.Instance == ground then
			local part = workspace.HoverPart
			part.Position = Vector3.new(target.X, 1.5, target.Z) --mouse.Hit.Position
			part.Color = Color3.new(0, 1, 0)
		end
	end
end)

game:GetService("UserInputService").InputBegan:Connect(function(input)
	if input.KeyCode == Enum.KeyCode.E then
		buttonPressed = not buttonPressed
	end
end)

mouse.Button1Down:Connect(function()
	if buttonPressed then
		local clone = workspace.HoverPart:Clone()
		clone.Parent = ground
		clone.Transparency = 0
		clone.Color = Color3.new(163, 162, 165)
		clone.CanCollide = true
	end
end)