Finding enemies within a angle and distance

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#1

Hello! Currently I am working on an boss fight and im wondering how would you find enemies within a angle/triangle something like this
image
Ex: Orange is boss, Blue is angle, Pink is enemies, x’s are for not included in the count (not in angle)
I want it to find every enemy within the angle and distance but not the enemies not inside the angle, something like vision

1 Like
#2

Could dot products be a possible solution here? You could incorporate a distance check as well to determine if players are close enough in some given angle.

local function isPlayerInLineOfSight(player)
local lookDirection = rootPart.CFrame.LookVector
local directionToPlayer = (player.PrimaryPart.Position - rootPart.Position).Unit

local angle = lookDirection:Dot(directionToPlayer)

if angle < 1 then
--//Player is in line of sight
end
end

Could also adjust the maximum angle it can be, I believe anything less than 1 is in front of the NPC, and anything negative is behind it. You should be able to tighten this, and also incorporate a distance check to see if players in line of sight are also close enough.

3 Likes
#3

Another thing to consider is what you want the 3D shape of the “angle” to be. Do you want “full 3D” angle, i.e. a cone shape, or do you want more of a 2D, top-down type angle, i.e. ignoring the height component for a “two planes” type of shape?

For the cone-type shape, this should work:

function vectorAngle(v1: Vector3, v2: Vector3): number
    --Explanation here: https://devforum.roblox.com/t/b/208450/4
    return math.acos(v1.Unit:Dot(v2.Unit))
end

function isPointInCone(point: Vector3, coneBase: Vector3, coneDir: Vector3, coneAngle: number): boolean
    local baseToPoint = point - coneBase
    local angle = vectorAngle(baseToPoint, coneDir)
    return angle < coneAngle
end

function isPointInRange(point: Vector3, pointFrom: Vector3, maxRange: number, minRange: number?): boolean
    local d = (point - pointFrom).Magnitude
    return d  == math.clamp(d, minRange or 0, maxRange)
end

  function isPointInView(point: Vector3, view: Attachment, viewAngle: number, viewRange: number): boolean
      return isPointInCone(point, view.WorldPosition, view.WorldCFrame.LookVector, viewAngle) and
           isPointInRange(point, view.WorldPosition, viewRange) 
  end

For a two-planes-type shape you could just remove the Y component:

function isPointInBiPlaneFrustrum(
    point: Vector3, plane1Point: Vector3, plane1Normal: Vector3, 
    plane2Point: Vector3, plane2Normal: Vector3): boolean --I swear this function name makes sense SOMEHOW https://en.wikipedia.org/wiki/Frustum
    
    local pointToPlane1Point = plane1Point - point
    local pointToPlane2Point = plane2Point - point
    local rightSideOfPlane1 = pointToPlane1Point:Dot(plane1Normal) > 0
    local rightSideOfPlane2 = pointToPlane2Point:Dot(plane2Normal) > 0
    return rightSideOfPlane1 and rightSideOfPlane2
end

function isPointInView(point: Vector3, view: Attachment, viewAngle: number, viewRange: number)
	local planeNormal1 = (view.WorldCFrame * CFrame.Angles(0, -viewAngle/2, 0)).LookVector
	local planeNormal2 = (view.WorldCFrame * CFrame.Angles(0,  viewAngle/2, 0)).LookVector
	
	A.CFrame = CFrame.new(view.WorldPosition, view.WorldPosition + planeNormal1) * CFrame.new(5, 0, 0)
	B.CFrame = CFrame.new(view.WorldPosition, view.WorldPosition + planeNormal2) * CFrame.new(-5, 0, 0)
	
	return isPointInBiPlaneFrustrum(point, view.WorldPosition, planeNormal1, view.WorldPosition, planeNormal2) 
		and isPointInRange(point, view.WorldPosition, viewRange) 
end

Here’s an illustration of what the view shape looks like, defined by a “Boss” part:

image
image701×600 34 KB

6 Likes
#4

Hey its been a while since you sent this, im a bit confused on what to insert into the functions, for the cone shape without the y component, these are functions so where would i get the a,b in isPointInView, and how would I really use these in a function to check?

#5

Whoops, looks like those were just some debugging things I forgot to remove. You should be able to just remove those two lines beginning with A.CFrame and B.CFrame.

You can use the functions to check if a specific point is inside the shape that each function represents. So if you have a list of all enemies, you can get a list of all enemies in view by looping through all enemies, checking if each one is in view, and inserting them into another table if they are.

#6

Could you show me a way I could maybe use this idk how to use the functions well