Most performant way to detect players in a radius

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#1

I’m looking for a performant way to detect mass amounts of players in a radius. First thing that came to mind when I was brainstorming was Roblox’s explosion instance. I had used it before for a similar purpose, and worked fine then. One concern about this method is how efficient it is. Would I be better off detecting players via Region3 or magnitude?

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#2

Region3 is deprecated. You should use worldroot:GetPartBoundsInRadius(position, radius, overlapParams). instead if you intend to follow that route.

function getRoots()
    local roots = {}
    for _,player in pairs(game.Players:GetChildren()) do
        if player.Character and player.Character:FindFirstChild("HumanoidRootPart") then
            table.insert(roots,player.Character.HumanoidRootPart)
        end
    end
    return roots
end

position = Vector3.new(0,0,0)
radius = 15
overlapParams = OverlapParams.new()
overlapParams.FilterType = Enum.FilterType.Whitelist
overlapParams.FilterDescendantsInstances = getRoots()

nearbyPlayers = workspace:GetPartBoundsInRadius(position, radius, overlapParams)

Or just iterate through game.Players and check magnitude. I don’t know how to answer which would be faster.

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#3

I believe Magnitude would work best for your purposes. Region3 can be quite costly for a lot of instances.

#4

Wow I didn’t even realize Region3 was deprecated lol. I appreciate the answer, but I do know one thing. Iterating through a bunch of parts and calculating magnitude is not efficient if your aoe is small. workspace:GetPartBoundsInRadius() is likely more performant in everyway, yet that doesn’t answer if roblox’s Explosion instance is less performant.

#5

It’s actually pretty efficient on the client and doesn’t cause any noticeable lag. You should do some benchmarking tests and see which one fits better.

#6

I’ve read somewhere that iterating through every part in the workspace at once and calculating magnitude is definitely not as performant as some other methods.
I got the explosion idea from:

Here is where I read about different use cases:

I’m performing aoe attack checks on the server for context. Because the aoe isn’t very big, continuing with roblox’s explosions should be performant, but I don’t know exactly how roblox explosions detect parts in the first place.

#7

I’ll probably end up doing that anyways, but I was curious to see if anyone on the forum could just outright tell me lol

#8

Decided to go with this method anyways because roblox explosions require you to listen for the hit event (I prefer to do everything in one thread)

#9

Explosions have a BlastRadius property already, there’s no need to reinvent the wheel. Additionally, RBXScriptConnection objects (connections) made from its Hit RBXScriptSignal object (event/signal) pass the hit distance, that is, the distance between the explosion’s position and the hit part’s position to any connected callback function(s).

local Workspace = workspace

local function OnHit(HitPart, HitDistance) --Connected callback function is passed hit part and hit distance as arguments.
	--Perform desired code.
end

local Explosion = Instance.new("Explosion")
Explosion.Position = Vector3.new(0, 0, 0) --Specify a 3D environment position.
Explosion.Hit:Connect(OnHit) --Create connection to 'Hit' event/signal.
Explosion.Parent = Workspace
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#10

You dont need to iterate through “every part in the workspace” just iterate through the player list and get the players’ character models. Then do a simple distance check from the character to the point using .Magnitude. Almost certain that would be the best option here.

#11

Doing this is pretty simple.

There are two methods

  1. Radius
  2. GetPartsInPart or GetPartsBoundInRadius

If your explosions are in the shape of a sphere, I would use Radius/Magnitude as it is very lag efficient. To do this as optimally as possible, I would use CollectionService to tag all humanoid root parts in the game (npc and player)

local CollectionService = game:GetService("CollectionService")

local function getEntitiesInRadius(origin, radius)
	local entities = {}
	
	local rootParts = CollectionService:GetTagged("HumanoidRootParts")
	for i, part in pairs(rootParts) do
		if (part.Position - origin) <= radius then
			table.insert(entities, part.Parent) --Inserting the character into the 'entities' table
		end
	end
	
	return entities
end

local entities = getEntitiesInRadius(character.HumanoidRootPart.Position, 30) --Get entities within 30 studs

I would not use roblox’s Explosions as you are more limited to what you can do, and it is not as optimal as this method.

1 Like
#12

Yes, I understood how roblox explosions worked from the getgo, but I wanted to know if they had any performance drawbacks or drawbacks at all.

#13

Iterating through only the player list doesn’t account for NPC’s nor’ Hurtboxes. It’s imperative that I know which part was hit because I need to know if it was a Hurtbox or not. GetPartBoundsInRadius allows me to only get the parts in that region, so I only have to iterate through a few parts compared to the entire workspace.

#14

Yeah, I stopped using explosions when I realized I have to pass arguments from the Hit Event. I ended up going with GetPartBoundsInRadius because the area i’m detecting is fairly small.

#15

workspace:GetPartBoundsInRadius can get kinda slow if you use a large radius I would benchmark it with looping every player and doing a magnitude check because I believe that can be faster then workspace:GetPartBoundsInRadius specially if your using a large radius