ddd

local Player = game.Players.LocalPlayer
local Screen = script.Parent
local Camera = workspace.CurrentCamera
    local FieldOfView   = Camera.FieldOfView --//will be abbreviated as FOV when paired with other words (e.g. MyFOV)
    local XY_FOV_RATIO  = .7 --//The X and Y axis do not both cover 70 degrees, so this scales it down


--//returns four vectors in a table such that:
--//table.x = [x lower bound lookvector, x upper bound lookvector]
--//table.y = [y lower bound lookvector, y upper bound lookvector]
--//input cameraDirection is the camera CFrame, fieldOfView is the Field of View in radians

local function GetCameraBoundsInCameraSpace(fieldOfView)
    local RadianHalfFOV = math.rad(fieldOfView*.5)

    --//Finds all the lookVector camera bounds via rotation
    local LowerCameraBoundY = CFrame.Angles( RadianHalfFOV,0,0).lookVector
    local UpperCameraBoundY = CFrame.Angles(-RadianHalfFOV,0,0).lookVector

    --//Y is straight foreward because FOV is based off of it, we have to
    --//do some modifications for X though

    local ScaleFromYtoX = Screen.AbsoluteSize.X/Screen.AbsoluteSize.Y

    local UpperCameraBoundYHeight = UpperCameraBoundY.Y
    local UpperCameraBoundYDepth  = UpperCameraBoundY.Z

    local UpperCameraBoundXSize   = UpperCameraBoundYHeight*ScaleFromYtoX


    local LowerCameraBoundX = Vector3.new(-UpperCameraBoundXSize,0,UpperCameraBoundYDepth).unit
    local UpperCameraBoundX = Vector3.new( UpperCameraBoundXSize,0,UpperCameraBoundYDepth).unit

    local X_FOVAngle = math.deg(2*math.atan(UpperCameraBoundXSize/UpperCameraBoundYDepth)) --simply 2tan^-1(y/x)

    return {
        X = {["Lower"] = LowerCameraBoundX, ["Upper"] = UpperCameraBoundX};
        Y = {["Lower"] = LowerCameraBoundY, ["Upper"] = UpperCameraBoundY};

        X_FOV = X_FOVAngle;
        Y_FOV = fieldOfView; --//Also returns field of view for math purposes
    }
end


--//returns a normalised vector projected onto an object-space plane on the camera
local function ProjectVectorOntoCameraPlane(cameraDirection, vectorPointingToPart, plane)
    local ProjectedVector --//vectorPointingToPart projected onto plane

    local CameraObjectSpaceVector;
    --//essentially the X component on the screen
    if plane == "XZ" then
        CameraObjectSpaceVector = cameraDirection:vectorToObjectSpace(vectorPointingToPart)
        ProjectedVector         = Vector3.new(CameraObjectSpaceVector.x,0,CameraObjectSpaceVector.z) --//removes Y component so the vector becomes 2D on XZ

    --//essentially the Y component on the sreen
    elseif plane == "YZ" then
        CameraObjectSpaceVector = cameraDirection:vectorToObjectSpace(vectorPointingToPart)
        ProjectedVector         = Vector3.new(0,CameraObjectSpaceVector.y,CameraObjectSpaceVector.z) --//removes Z component so the vector becomes 2D on XY
    end

    return ProjectedVector.unit
end


--//returns a normalized vector pointing from from to to (heh)
local function PointToVector3(from, to)
    return (to-from).unit
end

--//returns angles between vectors in degrees
local function FindDegreesBetweenVectors(vector1, vector2)
    return math.deg(math.acos(vector1.unit:Dot(vector2.unit)))
end

--//returns Absolute X and Absolute Y positions of a 3D position
local function ObtainScreenPositionFrom3DPosition(position, camera, fieldOfView)
    local ObjectIsOutsideOfScreenBounds = false
    local AbsoluteXPosition;
    local AbsoluteYPosition;

    --//General X and Y position stuff
        local DirectionToPartFromCamera  = PointToVector3(camera.CoordinateFrame.p,position)
        local CameraBounds = GetCameraBoundsInCameraSpace(fieldOfView) --//this can be moved outside the function and achieve the same effect

        local FieldOfViewAlongXAxis = CameraBounds.X_FOV
        local FieldOfViewAlongYAxis = CameraBounds.Y_FOV --//the same as fieldOfView ALWAYS

    --//Finding the approximate X pixel value
        local PartDirectionInCameraSpaceXZ = ProjectVectorOntoCameraPlane(camera.CoordinateFrame, DirectionToPartFromCamera, "XZ")

        local AngleFromLowerBoundX = FindDegreesBetweenVectors(CameraBounds.X.Lower, PartDirectionInCameraSpaceXZ)
        local AngleFromUpperBoundX = FindDegreesBetweenVectors(CameraBounds.X.Upper, PartDirectionInCameraSpaceXZ)

        if AngleFromLowerBoundX <= FieldOfViewAlongXAxis and AngleFromUpperBoundX <= FieldOfViewAlongXAxis then --//if it doesn't extends beyond the degrees in the FOV
            AbsoluteXPosition = (AngleFromUpperBoundX / FieldOfViewAlongXAxis) * Screen.AbsoluteSize.X --//basically ratio of way across screen (yes, scale!) * #pixels
        else
            ObjectIsOutsideOfScreenBounds = true
        end

    --//Finding the approximate Y pixel value
        local PartDirectionInCameraSpaceXY = ProjectVectorOntoCameraPlane(camera.CoordinateFrame, DirectionToPartFromCamera, "YZ")


        local AngleFromLowerBoundY = FindDegreesBetweenVectors(CameraBounds.Y.Lower, PartDirectionInCameraSpaceXY)
        local AngleFromUpperBoundY = FindDegreesBetweenVectors(CameraBounds.Y.Upper, PartDirectionInCameraSpaceXY)

        if AngleFromLowerBoundY <= FieldOfViewAlongYAxis and AngleFromUpperBoundY <= FieldOfViewAlongYAxis then --//if it doesn't extends beyond the degrees in the FOV
            AbsoluteYPosition = (AngleFromLowerBoundY / FieldOfViewAlongYAxis) * Screen.AbsoluteSize.Y --//basically ratio of way across screen (yes, scale!) * #pixels
        else
            ObjectIsOutsideOfScreenBounds = true
        end

    return ObjectIsOutsideOfScreenBounds and Vector2.new(0,0) or Vector2.new(AbsoluteXPosition, AbsoluteYPosition)
end


--//main body ok


local function main()
    local GUIThing = Instance.new("Frame",Screen)
        GUIThing.Size = UDim2.new(0,5,0,5)


    while wait() do

        local cameraBounds = GetCameraBoundsInCameraSpace(FieldOfView)

        --//moves a GUI around to cover 0,0
        local XYPos = ObtainScreenPositionFrom3DPosition(Vector3.new(0,0,0),Camera,FieldOfView)
        if XYPos ~= Vector2.new(0,0) then
            GUIThing.Visible  = true
            GUIThing.Position = UDim2.new(0,XYPos.X,0,XYPos.Y)
        else
            GUIThing.Visible  = false
        end
    end
end

main()