How would I cast a ray to where my mouse hit

Help and Feedback Scripting Support
1

I am making a gun and I want to cast a ray to detect if the player should be damaged or not.

I know how to create a ray but I don’t know how to make it go to the position that is clicked

This is what I have

local BulletRay = Ray.new(script.Parent.Handle.Emitter.Position, mouse.Hit.lookVector * 100)
	local Hit, Position = game.Workspace:FindPartOnRayWithIgnoreList(BulletRay, IgnoreList)
	Shoot(Hit)
10 Likes
2

Try using Mouse.Target instead. You can read about this here Mouse.Target.

5 Likes
3

You can use CFrame.p which is basically like a translator that converts CFrame to Vector3.

local BulletRay = Ray.new(script.Parent.Handle.Emitter.Position, mouse.Hit.p * 100)

This also works when you shoot in the air, unlike Mouse.Target.

3 Likes
4
Extra

Ray has a Unit property. If you end up having to use such property, its direction property is the exact same as the normal one. (ray.Unit.Direction = ray.Direction)

:ViewportPointToRay() does not accurately go where the mouse is. Better to use :ScreenpointToRay().

Mouse is superceded by UserInputService so while Mouse.Hit works, you will be at a disadvantage when wanting to implement things that UserInputService or ContextActionService have.

But it’ll take longer than just Mouse.Hit of course so you could use a module that acts similar but it’s not that complicated.

You get X, Y coordinate values which represent a 2D point on the screen (since your screen is just a flat 2D plane of space you’re looking through) then you can use :ViewportPointToRay() or :ScreenPointToRay() that accepts the X, Y parameters into it plus an optional depth parameter.

However, I believe depth moves the origin forward which we don’t want to have.

Though, the direction property gives a directional vector that is one stud long so we can multiply it to increase the distance/range. (500 is used here)

The RayParams is officially newer raycasting API so you might want to use it instead of the FindPartOnRay functions. You can also use the new :Raycast() function. The Ray object is still useful if you want to use its origin & direction.

local camera = workspace.CurrentCamera

local params = RaycastParams.new()
params.FilterDescendantsInstances = {} -- anything you want, for example the player's character, the ray filters through these
params.FilterType = Enum.RaycastFilterType.Exclude -- choose exclude or include
local function rayResult(x, y)
    local unitRay = camera:ScreenPointToRay(x, y) -- :ViewportPointToRay() is another choice
    return workspace:Raycast(unitRay.Origin, unitRay.Direction * 500, params) -- 500 is how far to raycast
end

-- rayResult will be a RaycastResult, link to API page below

Learn more here:
https://create.roblox.com/docs/reference/engine/classes/WorldRoot#Raycast
https://create.roblox.com/docs/reference/engine/datatypes/RaycastResult

To get x and y values for the function, use the function UserInputService:GetMouseLocation() for a Vector2 of the mouse position. However, this is only for mouse users.

For non-mouse users, get the position of an InputObject or a Vector2 argument from a ContextActionService binded function or UserInputService event connected function. (some mobile events receive a Vector2 argument instead of input object)

Example Scripts with above code

Example (mouse):

local mousePos = UserInputService:GetMouseLocation()
rayResult(mousePos.X, mousePos.Y)

Example (mouse & mobile supported):

local uis = game:GetService("UserInputService")
uis.InputEnded:Connect(function(input, gameProcessed) -- not exactly a click, but like the end of a mouse press or tap
    if not gameProcessed then
        local inputType = input.UserInputType
        if inputType == Enum.UserInputType.Touch or inputType == Enum.UserInputType.MouseButton1 then
            rayResult(input.Position.X, input.Position.Y)
        end
    end
end)

EDIT: Shortened answer for brevity. I actually googled my own answer once when I forgot how to do this stuff so I’m happy to see the many likes.

85 Likes
5 
local params = RayParams.new()

Why is RayParams nil??

1 Like
7

i mean my bad not nil but it says unknown global
image

1 Like
8

I made a mistake, change RayParams to RaycastParams.

4 Likes
9

For the direction I would recommend doing Mouse.UnitRay.Direction * 10000

10 Likes
15

Thank you for this. I have always had issues with this. Your reply helped me solve a problem I’ve had for some time now. :slight_smile:

16

very detailed explanation thx nice helped me alot

18

I hade problem where my ray isn’t directly at mouse position after changing rayDirection to mouse.UnitRay.Direction it finnaly worked !!! thanks a lot

1 Like