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How to tell if someone can see an object?

Asked by

6 years ago

I'm working on a part that does something when you look at it, I'm not exactly sure what I can do and I don't think lookVector would work, but I don't know much about it, I've been doing some research and I haven't found anything helpful, most of the things I found were too vague, or didn't seem like they would work. Any help would be nice, thanks in advance!

3 answers

Answered by

ozzyDrive 670

6 years ago

Edited 6 years ago

You can get the screen position of a 3D point with the WorldToScreenPoint method of the camera.

`1`	`local` `screenPoint, isVisible` `=` `camera:WorldToScreenPoint(object.Position)`

This however doesn't take the size of the object into account. What you can do is take all the corners of the object and see if any of them are on the screen. Here's an example on how this can be implemented:

01local localPlayer = game.Players.LocalPlayer
02local camera = workspace.CurrentCamera
03local part = workspace.Part
04 
05local GUI = Instance.new("ScreenGui", localPlayer.PlayerGui)
06local function drawFrame(topLeft, bottomRight)
07    local size = bottomRight - topLeft
08    local frame = Instance.new("Frame")
09 
10 
11    frame.Position = UDim2.new(0, topLeft.X - size.X/2, 0, topLeft.Y - size.Y/2)
12    frame.Size = UDim2.new(0, size.X, 0, size.Y)    
13    frame.BackgroundTransparency = 0.2
14    frame.BackgroundColor3 = BrickColor.Red().Color 
15 
16    frame.Parent = GUI
17 
18    game:GetService("Debris"):AddItem(frame, 1/30)
19end
20 
21local function isPartVisible(obj)   
22    local center = obj.Position
23 
24--  No need to do any extra calculations if the center point is on the screen
25    local centerPoint, centerVisible = camera:WorldToScreenPoint(center)
26    if centerVisible then
27        return true, centerPoint
28    end
29 
30    local extents = obj.Size/2 
31 
32    local extentPoints = {
33        [1] = (Vector3.new(center.X + extents.X, center.Y + extents.Y, center.Z + extents.Z)),
34        [2] = (Vector3.new(center.X - extents.X, center.Y - extents.Y, center.Z - extents.Z)),
35        [3] = (Vector3.new(center.X - extents.X, center.Y + extents.Y, center.Z + extents.Z)),
36        [4] = (Vector3.new(center.X + extents.X, center.Y - extents.Y, center.Z + extents.Z)),
37        [5] = (Vector3.new(center.X + extents.X, center.Y + extents.Y, center.Z - extents.Z)),
38        [6] = (Vector3.new(center.X - extents.X, center.Y - extents.Y, center.Z + extents.Z)),
39        [7] = (Vector3.new(center.X + extents.X, center.Y - extents.Y, center.Z - extents.Z)),
40        [8] = (Vector3.new(center.X - extents.X, center.Y + extents.Y, center.Z - extents.Z)),
41    }  
42 
43    for n = 1, #extentPoints do
44        local point = extentPoints[n]
45        local screenPoint, isVisible = camera:WorldToScreenPoint(point)
46        drawFrame(screenPoint, screenPoint + Vector3.new(10, 10))
47        if isVisible then
48            return true, screenPoint
49        end
50    end
51    return false
52end
53 
54game:GetService("RunService").Heartbeat:Connect(function()
55    print(isPartVisible(part))
56end)
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edit: Of course it is possible that the object is on the screen without any of the 9 points being visible. The final method depends on what kind of requirements you have.

Thanks! All of the others said the same thing, but you also said how I can tell if you can see an object, but I can't see the center, I would've most likely ran into lots of problems if you didn't add that extra comment. Thanks! Inconcinnus 90 — 6y

Answered by

fredfishy 833

6 years ago

Edited 6 years ago

The WorldToScreenPoint method returns information about where on the screen a Vector3 is, but also whether or not it's visible.

This seems to be pretty much exactly what you're looking for, with the caveat that it only returns true if the precise Vector3 is visible. If You've got a large object, you might be able to see the edge of it before its .Position is visible on screen.

If you throw a brick into the workspace called "CanYouSeeMe", then the following should, when you click and hold, take away your health whenever you can see it, and give it back to you when you can't.

01script.Parent.Equipped:Connect(function(m)
02    held = false
03 
04    m.Button1Down:Connect(function()
05        local player = game:GetService("Players").LocalPlayer
06        local cam = workspace.CurrentCamera
07        local fov = math.rad(workspace.CurrentCamera.FieldOfView)
08        local mouse = player:GetMouse()
09        local character = player.Character
10        held = true
11 
12        while held and wait() do
13            local locationAndDepth, visible = cam:WorldToScreenPoint(workspace.CanYouSeeMe.Position)
14            if visible then
15                character.Humanoid:TakeDamage(1)
16            else
17                character.Humanoid.Health = character.Humanoid.Health + 1
18            end
19        end
20    end)
21 
22    m.Button1Up:Connect(function()
23        held = false
24    end)
25 
26    script.Parent.Unequipped:Connect(function()
27        held = false
28    end)
29end)
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Answered by

Avigant 2374

6 years ago

Use Camera:WorldToScreenPoint to accomplish this.

How to tell if someone can see an object?

3 answers

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