Pathfinding

Pathfinding is the process of moving a character or object (agent) along a logical path around obstacles to reach a destination, optionally avoiding hazardous materials or defined regions.

Navigation visualization#

To assist with pathfinding layout and debugging, Studio can render a navigation mesh and modifier labels. To enable them, toggle on Navigation mesh and Pathfinding modifiers from the Visualization Options widget in the upper‑right corner of the 3D viewport.

Navigation Mesh

With Navigation mesh enabled, colored areas show where a character might walk or swim. Small arrows indicate areas that a character will attempt to reach by jumping.

Pathfinding Modifiers

With Pathfinding modifiers enabled, text labels indicate specific materials and regions that are taken into consideration when using pathfinding modifiers.

Implementation#

Although pathfinding can be implemented in various ways through PathfindingService and its associated methods such as CreatePath(), this section uses the following pathfinding script for the player's character.

To test while reading:

1. IMPORTANT In the Explorer, select the StarterPlayer container. Then, in the Properties window, set both DevComputerMovementMode and DevTouchMovementMode to Scriptable.

2. Copy the following code into a LocalScript within StarterCharacterScripts, or get this package and drop it into StarterCharacterScripts.

   ```lua title="PlayerPathFollow (LocalScript in StarterCharacterScripts)" local PathfindingService = game:GetService("PathfindingService") local Players = game:GetService("Players") local RunService = game:GetService("RunService")

   local DESTINATION = Vector3.new(20, 0.5, 20) local GROUND_WAIT = 0.01 local VELOCITY_MULTIPLIER = 0.0625

   local path = PathfindingService:CreatePath({ AgentCanClimb = true, Costs = { Water = 20 } })

   local character = script.Parent local humanoid = character:WaitForChild("Humanoid") local waypoints local nextWaypointIndex local blockedConnection local currentWaypointReachedConnection local currentWaypointPlaneNormal = Vector3.zero local currentWaypointPlaneDistance = 0 local pathfinderWorking = false

   local function disconnectCurrentWaypointReachedConnection() if not currentWaypointReachedConnection then return end currentWaypointReachedConnection:Disconnect() currentWaypointReachedConnection = nil end

   local function isCurrentWaypointReached() if humanoid.FloorMaterial == Enum.Material.Air then return false end

   local reached = false if currentWaypointPlaneNormal ~= Vector3.zero then -- Compute the distance from humanoid to destination plane local dist = currentWaypointPlaneNormal:Dot(humanoid.RootPart.Position) - currentWaypointPlaneDistance -- Compute the component of the humanoid velocity that is towards the plane local velocity = -currentWaypointPlaneNormal:Dot(humanoid.RootPart.Velocity) -- Compute the threshold from the destination plane based on humanoid velocity local threshold = math.max(1.0, VELOCITY_MULTIPLIER * velocity) -- Consider waypoint reached if less then threshold in front of the plane reached = dist < threshold else reached = true end

   if reached then currentWaypointPlaneNormal = Vector3.zero currentWaypointPlaneDistance = 0 moveToNextWaypoint() end end

   local function calculateNextWaypointApproach() nextWaypointIndex += 1 if nextWaypointIndex > #waypoints then return false end local currentWaypoint = waypoints[nextWaypointIndex - 1] local nextWaypoint = waypoints[nextWaypointIndex] -- Build destination plane from next waypoint towards current one currentWaypointPlaneNormal = currentWaypoint.Position - nextWaypoint.Position -- Set normal perpendicular to Y plane when not climbing up if nextWaypoint.Label ~= "Climb" then currentWaypointPlaneNormal = Vector3.new(currentWaypointPlaneNormal.X, 0, currentWaypointPlaneNormal.Z) end if currentWaypointPlaneNormal.Magnitude > 0.000001 then currentWaypointPlaneNormal = currentWaypointPlaneNormal.Unit currentWaypointPlaneDistance = currentWaypointPlaneNormal:Dot(nextWaypoint.Position) end

   return true end

   local function resetWaypointData() humanoid:Move(Vector3.zero) currentWaypointPlaneNormal = Vector3.zero currentWaypointPlaneDistance = 0 disconnectCurrentWaypointReachedConnection() pathfinderWorking = false end

   local function waitForGround() while humanoid.FloorMaterial == Enum.Material.Air do task.wait(GROUND_WAIT) end end

   function moveToNextWaypoint() if calculateNextWaypointApproach() then disconnectCurrentWaypointReachedConnection() currentWaypointReachedConnection = RunService.Heartbeat:Connect(isCurrentWaypointReached) local nextWaypointPosition = waypoints[nextWaypointIndex].Position local nextWaypointAction = waypoints[nextWaypointIndex].Action humanoid:Move(nextWaypointPosition - humanoid.RootPart.Position) if waypoints[nextWaypointIndex + 1] and waypoints[nextWaypointIndex + 1].Label == "UseBoat" then nextWaypointIndex += 1 -- Call your own customized function to make agent use the boat

   elseif nextWaypointAction == Enum.PathWaypointAction.Jump then humanoid:ChangeState(Enum.HumanoidStateType.Jumping) while humanoid.FloorMaterial ~= Enum.Material.Air do task.wait(GROUND_WAIT) end humanoid:Move(nextWaypointPosition - humanoid.RootPart.Position) end else resetWaypointData() end end

   local function findStartingPoint(waypoints) nextWaypointIndex = 1 while nextWaypointIndex + 1 <= #waypoints do local dist = waypoints[nextWaypointIndex + 1].Position - humanoid.RootPart.Position dist = Vector3.new(dist.X, 0, dist.Z) if dist.magnitude >= 2 then return end nextWaypointIndex += 1 end end

   local function followPath() -- Compute the path pathfinderWorking = true waitForGround()

   local success, errorMessage = pcall(function() path:ComputeAsync(character.PrimaryPart.Position, DESTINATION) end) if not success or path.Status ~= Enum.PathStatus.Success then warn("Path not computed!", errorMessage) return end

   -- Get the path waypoints waypoints = path:GetWaypoints()

   -- Detect if path becomes blocked blockedConnection = path.Blocked:Connect(function(blockedWaypointIndex) -- Check if the obstacle is further down the path if blockedWaypointIndex >= nextWaypointIndex then -- Stop detecting path blockage until path is re-computed blockedConnection:Disconnect() resetWaypointData() -- Call function to re-compute new path followPath() end end)

   findStartingPoint(waypoints) moveToNextWaypoint() end

   followPath() ```

3. Edit the DESTINATION variable (LINE 5) to a Vector3 destination within the 3D world that the player character can reach.

4. Proceed through the following sections to learn about path computation and character movement.

Path creation#

Pathfinding is initiated through PathfindingService and its CreatePath() method (LINES 9–14). This method accepts an optional table of parameters which fine tune how the character (agent) moves along the path.

Path computation#

After you've created a valid path with CreatePath(), it must be computed by calling Path:ComputeAsync() with a Vector3 for both the starting point and destination (LINES 133–139).

Once the Path is computed, it will contain a series of waypoints that trace the path from start to end. These points can be gathered with the Path:GetWaypoints() method (LINE 142). The returned array is arranged in order of waypoints from path start to path end.

Path movement#

Each PathWaypoint consists of both a Position (Vector3) and Action (PathWaypointAction). To move a character containing a Humanoid, like a typical Roblox character, the best way is to call Humanoid:Move() from waypoint to waypoint and use the script's isCurrentWaypointReached() callback (LINES 32–56) to detect when the character reaches each waypoint.

Blocked paths#

Many Roblox worlds are dynamic; parts might move or fall and floors may collapse. This can block a computed path and prevent the character from reaching its destination. To handle this, you can connect the Path.Blocked event and re-compute the path around whatever blocked it (LINES 145–154).

Pathfinding modifiers#

By default, Path:ComputeAsync() returns the shortest path between the starting point and destination, with the exception that it attempts to avoid jumps. This looks unnatural in some situations; for instance, a path may go through swamp water rather than around it simply because the path through the water is geometrically shorter.

To optimize pathfinding even further, you can implement pathfinding modifiers to compute smarter paths across various materials, around defined regions, or to ignore obstacles.

Material costs#

When working with Terrain and BasePart materials, you can include a Costs table within CreatePath() to make certain materials more traversable than others. All materials have a default cost of 1 and any material can be defined as non‑traversable by setting its value to math.huge.

Keys in the Costs table should be string names representing Material names, for example Water for Material.Water or CrackedLava for Material.CrackedLava.

local PathfindingService = game:GetService("PathfindingService")
local Players = game:GetService("Players")
local RunService = game:GetService("RunService")

local DESTINATION = Vector3.new(20, 0.5, 20)
local GROUND_WAIT = 0.01
local VELOCITY_MULTIPLIER = 0.0625

local path = PathfindingService:CreatePath({
	AgentCanClimb = true,
	Costs = {
		Water = 20, CrackedLava = 100, Slate = 20
	}
})

Configure regions#

In some cases, material preference is not enough. For example, you might want characters to avoid a defined region, regardless of the materials underfoot. This can be achieved by adding a PathfindingModifier object to a part.

1. Create an Anchored part around the region and set its CanCollide property to false.

   

2. Insert a PathfindingModifier instance onto the part, locate its Label property, and assign a meaningful name like DangerZone.

   

3. Include a matching DangerZone key and associated numeric value within the Costs table of CreatePath(). A modifier can be defined as non‑traversable by setting its value to math.huge.

   ```lua title="PlayerPathFollow (LocalScript)" local PathfindingService = game:GetService("PathfindingService") local Players = game:GetService("Players") local RunService = game:GetService("RunService")

   local DESTINATION = Vector3.new(20, 0.5, 20) local GROUND_WAIT = 0.01 local VELOCITY_MULTIPLIER = 0.0625

   local path = PathfindingService:CreatePath({ AgentCanClimb = true, Costs = { DangerZone = math.huge, Water = 20, CrackedLava = 20, Slate = 20 } }) ```

Ignore obstacles#

In some cases, it's useful to pathfind through solid obstacles as if they didn't exist. This lets you compute a path through specific physical blockers, versus the computation failing outright.

1. Create an Anchored part around the object and set its CanCollide property to false.

   

2. Insert a PathfindingModifier instance onto the part and enable its PassThrough property.

   

   Now, when a path is computed from the zombie NPC to the player character, the path extends beyond the door and you can prompt the zombie to traverse it. Even if the zombie is unable to open the door, it reacts as if it "hears" the character behind the door.

   

Pathfinding links#

Sometimes it's necessary to find a path across a space that cannot be normally traversed, such as across a chasm, and perform a custom action to reach the next waypoint. This can be achieved through the PathfindingLink object.

Using the example from above, you can make the agent use a boat.

To create a PathfindingLink using this example:

1. OPTIONAL Toggle on Pathfinding links from the Visualization Options widget in the upper‑right corner of the 3D viewport. This helps with visualization and debugging when implementing pathfinding links.

2. Create two Attachments, one on the boat's seat and one near the boat's landing point.

   

3. Create a PathfindingLink object in the workspace, then assign its Attachment0 and Attachment1 properties to the starting and ending attachments respectively.

   

4. Assign a meaningful name like UseBoat to its Label property. This name is used as a flag in the pathfinding script to trigger a custom action when the agent reaches the starting link point.

   

5. Include a Costs table within CreatePath() containing both a Water key and a custom key matching the Label property name. Assign the custom key a value lower than that of Water.

   ```lua title="PlayerPathFollow (LocalScript)" local PathfindingService = game:GetService("PathfindingService") local Players = game:GetService("Players") local RunService = game:GetService("RunService")

   local DESTINATION = Vector3.new(20, 0.5, 20) local GROUND_WAIT = 0.01 local VELOCITY_MULTIPLIER = 0.0625

   local path = PathfindingService:CreatePath({ AgentCanClimb = true, Costs = { UseBoat = 2, Water = 20 } }) ```

6. In the moveToNextWaypoint() function (LINES 93–114), a custom check for the Label modifier name can be used to take a different action than Humanoid:Move(); in this case, you might call a function to seat the agent in the boat, move the boat across the water, unseat the agent at the boat's landing point, and then continue the agent's path to its final destination.

Streaming compatibility#

In-game instance streaming is a powerful feature that dynamically loads and unloads 3D content as a player's character moves around the world. As they explore the 3D space, new subsets of the space stream to their device and some of the existing subsets might stream out.

Consider the following best practices for using PathfindingService in streaming-enabled games:

• Streaming can block or unblock a given path as a character moves along it. For example, while a character runs through a forest, a tree might stream in somewhere ahead of them and obstruct the path. To make pathfinding work seamlessly with streaming, it's highly recommended that you use the handling blocked paths technique and re-compute the path when necessary.

• A common approach in pathfinding is to use the coordinates of existing objects for computation, such as setting a path destination to the position of an existing TreasureChest model in the world. This approach is fully compatible with server-side Scripts since the server has full view of the world at all times, but LocalScripts and ModuleScripts that run on the client may fail if they attempt to compute a path to an object that's not streamed in.

  To address this issue, consider setting the destination to the position of a BasePart within a persistent model. Persistent models load soon after the player joins and they never stream out, so a client-side script can connect to the PersistentLoaded event and safely access the model for creating waypoints after the event fires.

Limitations and failure factors#

The pathfinding engine includes specific limitations to ensure efficient processing and optimal performance. Additionally, pathfinding computations can fail for various reasons as outlined below.