Flattened version of Camera:ScreenPointToRay()

[PehqDev (ペクさま)]

Hello folks, I need help with a thing I am working on…

So I have set up a script in which the camera will shoot out rays 100 studs outwards and move the attachment.

local PosUI2d = UserInputService:GetMouseLocation() --Gets updated in another function...

local function MoveAttachment()
	local BaseRay:Ray = Cam:ScreenPointToRay(PosUI2d.X, PosUI2d.Y, DIST_FROM_CAM) --this curves...
	local Pos3D = BaseRay.Origin + BaseRay.Direction
	
	--DEBUG
	local x= Instance.new("Part")
	x.Position = Pos3D
	x.Size = Vector3.one
	x.Color = Color3.new(1,0,0)
	x.Anchored = true
	x.Parent = workspace.Tmp
	--DEBUG END
	
	Att.CFrame = CFrame.new(Pos3D)
end

Here’s that visualized

Now if I look around, then the generated (from the Ray) shape appears to be curved.

How do I make it so that it is flat?

[PehqDev (ペクさま)]

Figured it out, I needed to make a plane in front of the camera then get the intersection of the ray to the plane.

local function MoveChar()
	local ray = Cam:ScreenPointToRay(PosUI2d.X, PosUI2d.Y, 0)

	-- making a plane in front of the camera
	local DIST = DIST_FROM_CAM
	local camPos    = Cam.CFrame.Position
	local camLook   = Cam.CFrame.LookVector
	local planePos  = camPos + camLook * DIST
	local planeNorm = camLook

	-- getting the intersection of the ray and the plane
	local numer = (planePos - ray.Origin):Dot(planeNorm)
	local denom = ray.Direction:Dot(planeNorm)
	if math.abs(denom) < 1e-6 then
		return -- the ray is nearly parallel to le plane
	end
	local t = numer / denom
	local Pos3D = ray.Origin + ray.Direction * t

	-- DEBUG
	local x = Instance.new("Part")
	x.Position = Pos3D
	x.Size     = Vector3.new(1,1,1)
	x.Color    = Color3.new(1,0,0)
	x.Anchored = true
	x.Parent   = workspace.Tmp

	-- update CFrame (if needed)
	Att.CFrame = CFrame.new(Pos3D)
end