58 lines
5.0 KiB
Markdown
58 lines
5.0 KiB
Markdown
# Using NavMesh Agent with Other Components
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You can use [**NavMesh**][1] Agent, NavMesh Obstacle, and Off [**Mesh**][2] Link components with other Unity components too. Here’s a list of dos and don’ts when mixing different components together.
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## NavMesh Agent and Physics
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- You don’t need to add physics [**colliders**][3] to NavMesh Agents for them to avoid each other
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- That is, the navigation system simulates agents and their reaction to obstacles and the static world. Here the static world is the baked NavMesh.
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- If you want a NavMesh Agent to push around physics objects or use physics triggers:
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- Add a Collider component (if not present)
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- Add [**Rigidbody**][4] component
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- Turn on kinematic (Is Kinematic) - this is important!
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- Kinematic means that the rigid body is controlled by something else than the physics simulation
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- If both NavMesh Agent and Rigidbody (non-kinematic) are active at the same time, you have race condition
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- Both components may try to move the agent at the same which leads to undefined behavior
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- You can use a NavMesh Agent to move e.g. a player character, without physics
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- Set players agent’s avoidance priority to a small number (high priority), to allow the player to brush through crowds
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- Move the player agent using [NavMeshAgent.velocity](https://docs.unity3d.com/ScriptReference/AI.NavMeshAgent-velocity.html), so that other agents can predict the player movement to avoid the player.
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## NavMesh Agent and Animator
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- NavMesh Agent and Animator with [**Root Motion**][5] can cause race condition
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- Both components try to move the transform each frame
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- Two possible solutions
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- Information should always flow in one direction
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- Either agent moves the character and animations follows
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- Or animation moves the character based on simulated result
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- Otherwise you’ll end up having a hard to debug feedback loop
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- _Animation follows agent_
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- Use the [NavMeshAgent.velocity](https://docs.unity3d.com/ScriptReference/AI.NavMeshAgent-velocity.html) as input to the Animator to roughly match the agent’s movement to the animations
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- Robust and simple to implement, will result in foot sliding where animations cannot match the velocity
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- _Agent follows animation_
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- Disable [NavMeshAgent.updatePosition](https://docs.unity3d.com/ScriptReference/AI.NavMeshAgent-updatePosition.html) and [NavMeshAgent.updateRotation](https://docs.unity3d.com/ScriptReference/AI.NavMeshAgent-updateRotation.html) to detach the simulation from the game objects locations
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- Use the difference between the simulated agent’s position ([NavMeshAgent.nextPosition](https://docs.unity3d.com/ScriptReference/AI.NavMeshAgent-nextPosition.html)) and animation root ([Animator.rootPosition](https://docs.unity3d.com/ScriptReference/Animator-rootPosition.html)) to calculate controls for the animations
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- See [Coupling Animation and Navigation](CouplingAnimationAndNavigation.md) for more details
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## NavMesh Agent and NavMesh Obstacle
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- Do not mix well!
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- Enabling both will make the agent trying to avoid itself
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- If carving is enabled in addition, the agent tries to constantly remap to the edge of the carved hole, even more erroneous behavior ensues
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- Make sure only one of them are active at any given time
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- Deceased state, you may turn off the agent and turn on the obstacle to force other agents to avoid it
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- Alternatively you can use priorities to make certain agents to be avoided more
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## NavMesh Obstacle and Physics
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- If you want physics controlled object to affect NavMesh Agent’s behavior
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- Add NavMesh Obstacle component to the object which agent should be aware of, this allows the avoidance system to reason about the obstacle
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- If a game object has a Rigidbody and a NavMesh Obstacle attached, the obstacle’s velocity is obtained from the Rigidbody automatically
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- This allows NavMesh Agents to predict and avoid the moving obstacle
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[1]: ./Glossary.md "A mesh that Unity generates to approximate the walkable areas and obstacles in your environment for path finding and AI-controlled navigation."
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[2]: https://docs.unity3d.com/Manual/mesh-introduction.html "The main graphics primitive of Unity. Meshes make up a large part of your 3D worlds. Unity supports triangulated or Quadrangulated polygon meshes. Nurbs, Nurms, Subdiv surfaces must be converted to polygons."
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[3]: https://docs.unity3d.com/Manual/CollidersOverview.html "An invisible shape that is used to handle physical collisions for an object. A collider doesn’t need to be exactly the same shape as the object’s mesh - a rough approximation is often more efficient and indistinguishable in gameplay."
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[4]: https://docs.unity3d.com/Manual/class-Rigidbody.html "A component that allows a GameObject to be affected by simulated gravity and other forces."
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[5]: https://docs.unity3d.com/Manual/RootMotion.html "Motion of character’s root node, whether it’s controlled by the animation itself or externally."
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