Is there a simple way to get mouse hit position from its screen coordinates? [ACTUALLY SOLVED]

Keeping this up for future users.

The problem was that the depth argument for ScreenPointToRay is actually where the ray starts, and not the distance of the ray.

Original Post:

I'm switching some of my LocalScripts over to UserInputService, and am trying to remove my reliance on the Mouse object. Is there a method similar to Mouse.Hit, or a simple way to replace it? It doesn't have to use UserInputService exclusively, I just want to shy away from using the Mouse object now that it seems like Roblox is moving more in favor of UserInputService.

Solution:

I discovered a solution shortly after this post, if anyone want to know how I did it, just see below.

So, it turns out, Camera objects have this neat ScreenPointToRay function. It takes three arguments: x, y, and depth. x and y are the screen position. depth is the distance of the ray. It will then return a ray.

I then use FindPartOnRay with the screenpointtoray ray as the first argument, and the player character as the second, and set the third and fourth to false and true respectively. Which returns the target part, the point of intersection, the surface, and the material of the part or terrain. It also ignores the player, and water terrain.

You could also use FindPartOnRayWithIgnoreList if you wanted to have multiple items ignored.

current code:

local fndtn = script.Foundation
local play = game.Players.LocalPlayer
local UIP = game:GetService("UserInputService")
local camera = game.Workspace.CurrentCamera

function getHit(mouseX,mouseY)
    camera = game.Workspace.CurrentCamera
    local ray = camera:ScreenPointToRay(mouseX,mouseY,1000)
    print(ray.Origin)
    local rayorigin = Instance.new("Part")
    rayorigin.Size = Vector3.new(1,1,1)
    rayorigin.Position = ray.Origin
    rayorigin.Anchored = true
    rayorigin.Parent = game.Workspace
    rayorigin.BrickColor = BrickColor.new("Really red")
    rayorigin.Name = "Ray Origin"
    script.OriginGui:Clone().Parent = rayorigin
    print(ray.Direction)
    print(ray.Unit.Direction)
    local target, hit, surface, material = game.Workspace:FindPartOnRay(ray.Unit,play.Character,false,true)
    if target then print(target.Name..":Target") else print("notarget") end
    return hit
end


function inputB(inputObject, gameProcessedEvent)
    if inputObject.UserInputType == Enum.UserInputType.MouseButton1 then
        local X,Y = inputObject.Position.X, inputObject.Position.Y
        local hit = getHit(X,Y)
        clone = fndtn:Clone()
        clone.Position = hit
        clone.Parent = game.Workspace
        height = Y
        wid = X
        placeconnect = UIP.InputEnded:connect(inputE)
        changeconnect = UIP.InputChanged:connect(inputC)
    end
end

function inputE(inputObject, gameProcessedEvent)
    if inputObject.UserInputType == Enum.UserInputType.MouseButton1 then
    placeconnect:disconnect()
    changeconnect:disconnect()
    end
end

function inputC(inputObject, gameProcessedEvent)
    if inputObject.UserInputType == Enum.UserInputType.MouseMovement then
    local X,Y = inputObject.Position.X, inputObject.Position.Y
    if X > (wid) then
        wid = X
        clone.Size = Vector3.new(clone.Size.X+1,clone.Size.Y,clone.Size.Z+1)    
    elseif X < (wid) then
        wid = X
        clone.Size = Vector3.new(clone.Size.X-1,clone.Size.Y,clone.Size.Z-1)
    end

    if Y > (height) then
        height = Y
        clone.Size = Vector3.new(clone.Size.X,clone.Size.Y-1,clone.Size.Z)  
    elseif Y < (height) then
        height = Y
        clone.Size = Vector3.new(clone.Size.X,clone.Size.Y+1,clone.Size.Z)  
    end
    end
end

UIP.InputBegan:connect(inputB)

current problems:

The ray's origin seems to be 1,000 studs ahead of the camera. Causing it to ignore everything. image: https://i.gyazo.com/f6ac156f6ed745d1ecefb312e03b2770.png red dots are ray origins.