Alternative to Unity's NavMesh system where the agents avoid the other non-moving agents in their pathing. It uses the official navigation system, but you have to use its components instead. Compatible with NavMeshComponents.

Disclaimer: This tool has not been thoroughly tested.

How do the agents avoid others? Unity's NavMeshAgent only goes around NavMeshObstacles and ignores the other agents in their path. By disabling NavMeshAgent and enabling NavMeshObstacle when an agent is not moving noticeably, the agents now avoid other non-moving agents in their pathing.

Unity's NavMeshAgent	CustomNavMeshAgent

1. Set the destination to the blue target.

What if a moving agent collides against a stopped agent that's currently in obstacle mode? By default, it wouldn't be able to push it. However, by:

• duplicating the baked surface, obstacle, and agents;
• making the duplicated agents switch between NavMeshAgent and NavMeshObstacle instead of the original ones;
• having each original agent copy the duplicated one's velocity, and the duplicated one copy the original's position at every frame.

2. The duplicated NavMesh components. The hidden components are on the right side.

You can have agents push the other agents. This is how the CustomNavMesh system works under the hood. For it to work, you must use its custom components, which are identical to the original ones, making the transition seamless.

NavMeshAgent vs NavMeshObstacle "Agents"	CustomNavMeshAgents

3. Overlapping agents by throwing one against the others. The agents are red and the obstacles blue. This is just a showcase. If you're trying to do something similar, you should use colliders and physics instead since this system is only supposed to resolve agent overlap.

Why not just switch the agents back to NavMeshAgent instead? That wouldn't work because switching from NavMeshObstacle to NavMeshAgent isn't instant — it would take at least two frames.

What are the disadvantages? Every NavMesh component is duplicated, which makes it less performant. However, It shouldn't be noticeable unless you have a lot of agents.

CustomNavMesh – you can choose the hidden game objects relative position and whether or not they are rendered by accessing the class or through its singleton present in the scene.

4. Changing CustomNavMesh fields.

• CustomNavMeshSurface – add to each surface that is going to be baked. These surfaces need to be rendered meshes. Both Physics Colliders and Terrains are ignored by it;
• CustomNavMeshObstacle – replacement for NavMeshObstacle;
• CustomNavMeshAgent – replacement for NavMeshAgent. It has some added properties:
  • Time to Block – time in seconds needed for the agent to start blocking (to make others go around it), assuming it hasn't surpassed the Unblock Speed Threshold during the interval;
  • Unblock Speed Threshold – the speed at which the agent stops blocking and moves instead;
  • Block Refresh Interval – time in seconds needed for the agent to check if it should stop blocking;
  • Min Distance Boost to Stop Block - When block is refreshed, this is the minimum distance the newly calculated reachable position must be closer from the target — compared to its current distance from the target — for it to stop blocking;
  • The rest have to do with the blocking obstacle carving and are identical to the NavMeshObstacle carving settings.

Clone or download this repository and open the project in Unity. Alternatively, you can copy the contents of Assets/CustomNavMesh to an existing project.

The scenes used for the GIFs are available in the Assets/Examples folder. Just hit the Space Bar in play mode to test it.

Note: This project was created using Unity 2019.4 LTS version. Tested in PC Standalone, Android, and WebGL.

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.

Things that I might implement later:

• Every time an agent in block mode does a refresh (tries to see if it should unblock), SamplePosition and CalculatePath are called. Both of these functions are synchronous and run on the main thread. I could implement the new experimental NavMeshQuery operations (not yet fully complete) which can be can be executed inside jobs.
• Import more methods and properties from the NavMesh and NavMeshAgent to the CustomNavMesh and the CustomNavMeshAgent, respectively.
• Create custom versions for the NavMeshComponents' components.

If you need help implementing this to your project or have any questions, just message me and I'll try to help. I'm also interested in any tips or suggestions you may have, cheers!