How do I raycast the crosshair position

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#1

I’m making a gun system that use a button to fire a gun I created a cursor to raycast the position what I want to achieve is to get the crosshair position from the ScreenGui by using :Raycast() and not mouse position because most mobile users using their thumbstick while using a gun the touch position would get messed up

This is the script that I use from an old game: ROBLOX Battle [OPEN] - Roblox

local screenPosition = fakeCursor.AbsolutePosition + (fakeCursor.AbsoluteSize / 2)
				local screenSize = mainGui.AbsoluteSize

				local imagePlaneDepth = screenSize.Y / (2 * math.tan(math.rad(camera.FieldOfView) / 2))
				local direction = Vector3.new(screenPosition.X - (screenSize.X / 2), (screenSize.Y / 2) - screenPosition.Y, -imagePlaneDepth)
				local raycastResult = workspace:Raycast(camera.CFrame.Position, (camera.CFrame:VectorToWorldSpace(direction)).Unit * 999, raycastParams)

				if raycastResult then
					local char = raycastResult.Instance:FindFirstAncestorOfClass("Model") or raycastResult.Instance.Parent:FindFirstAncestorOfClass("Model")
					if char and char:IsDescendantOf(game) then
						local humanLink = char:FindFirstChild("HumanoidLink")
						if humanLink and humanLink:IsA("ObjectValue") and humanLink.Value and humanLink.Value:IsDescendantOf(game) then
							local plr = Players:GetPlayerFromCharacter(humanLink.Value.Parent)
							if plr then
								fakeCursor.BackgroundColor3 = if checkTeamKill(player, plr) 
									then Color3.fromRGB(85, 255, 0)
									else Color3.fromRGB(255, 255, 255)
							end
						else
							local plr = Players:GetPlayerFromCharacter(char)
							if plr then
								fakeCursor.BackgroundColor3 = if checkTeamKill(player, plr) 
									then Color3.fromRGB(85, 255, 0)
									else Color3.fromRGB(255, 255, 255)
							end
						end
					else
						fakeCursor.BackgroundColor3 = Color3.fromRGB(255, 255, 255)
					end
				end
1 Like
#2

Hey there, I think what you are specifically looking for is the Camera:ViewportPointToRay() method. It raycasts from a position on the screen. It’s exactly what is needed for an FPS game.

1 Like
#3

Camera:ViewportPointToRay() doesn’t seem accurate at all so I would go Camera:ScreenPointToRay() instead

#4

You should use ViewportPointToRay, it’s only inaccurate if you haven’t enabled IgnoreGuiInset on the ScreenGui, and if it isn’t enabled, your crosshair isn’t even centered on the screen.

#5

I have enabled IgnoreGuiInset but the problem with ViewportPointToRay is it can only raycast the top of the cursor and mouse location doesn’t

#6

What do you mean? ViewportPointToRay takes a 2D position, if the position is above your cursor, it’s an issue with your code.

#7

It’s because I use AbsolutePosition from the cursor frame

local currentPositionOnScreen = fakeCursor.AbsolutePosition
			local inputRay = camera:ScreenPointToRay(currentPositionOnScreen.X, currentPositionOnScreen.Y)

			local endPosition = inputRay.Origin + inputRay.Direction
			local cameraPosition = camera.CFrame.Position
			
			local raycastResult = workspace:Raycast(cameraPosition, (endPosition - cameraPosition).Unit * 5000, raycastParams)
			local plr = nil

			if raycastResult then
				local char = raycastResult.Instance:FindFirstAncestorOfClass("Model") or raycastResult.Instance.Parent:FindFirstAncestorOfClass("Model")			
				if char and char:IsDescendantOf(game) then
					plr = Players:GetPlayerFromCharacter(char)
					
					local humanLink = char:FindFirstChild("HumanoidLink")				
					if humanLink and humanLink:IsA("ObjectValue") and humanLink.Value and humanLink.Value:IsDescendantOf(game) then
						plr = Players:GetPlayerFromCharacter(humanLink.Value.Parent)
					end
				end
			end
			
			fakeCursor.BackgroundColor3 = if plr and checkTeamKill(player, plr) 
				then Color3.fromRGB(85, 255, 0)
				else Color3.fromRGB(255, 255, 255)
#8

What do you mean by “it can only raycast the top of the cursor”? I think it may be caused by you using AbsolutePosition without setting the crosshair’s AnchorPoint to 0.5, 0.5, and if you have set it to that, then can you explain or show a video or image of how ViewportPointToRay is not working?

Also,

Should be

local endPosition = inputRay.Origin + (inputRay.Direction * 5000)

And

Should be

inputRay.Direction * 5000
#9

I tried your code and it doesn’t work perfectly

using ViewportPointToRay would just get the YOffset decreased by -36 (topbar Y size)

#10

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