Using NavMesh Agent with Other Components

You can use NavMesh Agent, NavMesh Obstacle, and Off Mesh Link components with other Unity components too. Here’s a list of dos and don’ts when mixing different components together.

NavMesh Agent and Physics

• You don’t need to add physics colliders to NavMesh Agents for them to avoid each other
  • That is, the navigation system simulates agents and their reaction to obstacles and the static world. Here the static world is the baked NavMesh.
• If you want a NavMesh Agent to push around physics objects or use physics triggers:
  • Add a Collider component (if not present)
  • Add Rigidbody component
    • Turn on kinematic (Is Kinematic) - this is important!
    • Kinematic means that the rigid body is controlled by something else than the physics simulation
• If both NavMesh Agent and Rigidbody (non-kinematic) are active at the same time, you have race condition
  • Both components may try to move the agent at the same time which leads to undefined behavior
• You can use a NavMesh Agent to move e.g. a player character, without physics
  • Set players agent’s avoidance priority to a small number (high priority), to allow the player to brush through crowds
  • Move the player agent using NavMeshAgent.velocity, so that other agents can predict the player movement to avoid the player.

NavMesh Agent and Animator

• NavMesh Agent and Animator with Root Motion can cause race condition
  • Both components try to move the transform each frame
  • Two possible solutions
• Information should always flow in one direction
  • Either agent moves the character and animations follows
  • Or animation moves the character based on simulated result
  • Otherwise you’ll end up having a hard to debug feedback loop
• Animation follows agent
  • Use the NavMeshAgent.velocity as input to the Animator to roughly match the agent’s movement to the animations
  • Robust and simple to implement, will result in foot sliding where animations cannot match the velocity
• Agent follows animation
  • Disable NavMeshAgent.updatePosition and NavMeshAgent.updateRotation to detach the simulation from the game objects locations
  • Use the difference between the simulated agent’s position (NavMeshAgent.nextPosition) and animation root (Animator.rootPosition) to calculate controls for the animations
  • See Coupling Animation and Navigation for more details

NavMesh Agent and NavMesh Obstacle

• Do not mix well!
  • Enabling both will make the agent trying to avoid itself
  • If carving is enabled in addition, the agent tries to constantly remap to the edge of the carved hole, even more erroneous behavior ensues
• Make sure only one of them are active at any given time
  • Deceased state, you may turn off the agent and turn on the obstacle to force other agents to avoid it
  • Alternatively you can use priorities to make certain agents to be avoided more

NavMesh Obstacle and Physics

• If you want physics controlled object to affect NavMesh Agent’s behavior
  • Add NavMesh Obstacle component to the object which agent should be aware of, this allows the avoidance system to reason about the obstacle
• If a game object has a Rigidbody and a NavMesh Obstacle attached, the obstacle’s velocity is obtained from the Rigidbody automatically
  • This allows NavMesh Agents to predict and avoid the moving obstacle