111 lines
4.7 KiB
ReStructuredText
111 lines
4.7 KiB
ReStructuredText
.. _doc_real_time_navigation_3d:
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Real Time Navigation (3D)
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=========================
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Introduction
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------------
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Pathfinding in a 3D environment is crucial for many games, it's commonly
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how non directly controlled characters or entities find their way around
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an environment. Godot provides several nodes for this purpose:
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- :ref:`Navigation<class_Navigation>` (deprecated)
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- :ref:`NavigationMeshInstance<class_NavigationMeshInstance>`
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- :ref:`NavigationAgent<class_NavigationAgent>`
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- :ref:`NavigationObstacle<class_NavigationObstacle>`
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The map and navigation regions
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------------------------------
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The "map" is the entire world for navigation, it's similar to "space" for
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the physics engine. It's comprised of navigation regions, these regions
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define parts of the world that can be navigated around by navigation
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agents.
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To create a navigation region add the :ref:`NavigationMeshInstance<class_NavigationMeshInstance>`
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node to a 3D scene. Next in the inspector for that mesh create or add a
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:ref:`NavigationMesh<class_NavigationMesh>`. The navmesh contains options
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for how it will be generated when it's baked. The geometry options control
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which nodes, and types of nodes, are used to bake the mesh. A full
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description of each setting and how it works can be found in the :ref:`NavigationMesh class reference<class_NavigationMesh>`.
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Once the settings have been properly configured press the "Bake NavMesh"
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button at the top of the inspector to generate it.
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.. image:: img/bake_navmesh.png
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.. note::
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It can also be generated at runtime using the `bake_navigation_region()`
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method of the navigation region node.
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Once the mesh has finished generating you should see the transparent
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navigation mesh above the areas in the scene that can be navigated to.
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.. image:: img/baked_navmesh.png
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Keep in mind that the navmesh shows where the center of an entity can
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go. For example, if you set the agent radius to 0.5 then the
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navigation mesh will have a distance of 0.5 from any ledges or walls
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to prevent clipping into the wall or hanging off of the edge.
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Navigation agents can moved from one region to another if they are next
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to each other. Additionally a baked navmesh can be moved at runtime and
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agents will still be able to navigate onto it from another region.
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For example, navigating onto a moving platform that has stopped will work.
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NavigationAgent
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---------------
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Navigation agent nodes are what actually does the pathfinding in a scene,
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one can be attached to the root node of an entity that needs to navigate.
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To have it pathfind use its `set_target_location` method. Once the target
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has been set a path will be generated to the node using navigation regions,
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with several points on the way to the final destination.
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RVO processing
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--------------
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RVO stands for reciprocal velocity obstacle. RVO processing is a way to
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pathfind while taking into account other agents and physics bodies that
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are also moving.
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To use it set a target like normal. Then an agent needs to fetch its next
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nav path location, and compute its velocity to that location. Instead
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of using that value to move use it to set the velocity on the agent
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with `set_velocity`. Then a new velocity that takes into account other
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agents and obstacles is generated and emitted with the signal `velocity_computed`.
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However agents can only take into account a set number of other nearby
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agents, this is the :ref:`max neighbors<class_NavigationAgent_property_max_neighbors>`
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property of an agent and can be adjusted. This is **not** a limit for
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how many agents can use a navigation region at the same time.
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NavigationObstacle
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------------------
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This node is used to mark physics bodies that move around a navigation area
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that agents need to avoid (this will only work if you use RVO processing).
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For example, this node would be useful for pieces of debris in a destructible
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environment. Add it as the child of a physics body and navigation agent
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nodes will avoid it while pathfinding.
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Generating a path (old method)
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------------------------------
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This is the old method for generating a navigation path, it will be
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removed in Godot 4. First, add a navigation node to the scene, then
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add a navigation mesh instance as it's child and set up a navigation
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mesh.
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To get a path between two areas on a map you use the navigation node
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method ``get_simple_path()``. The first argument is a Vector3 of the
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starting location, the next is a Vector3 of the end location. And the
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last argument is a boolean for whether or not agent properties of a
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navmesh are considered when generating a path.
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The method will return a :ref:`PoolVector3Array <class_PoolVector3Array>` consisting of
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points that make a path. If there is no way to navigate to the end
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location the method will return a blank :ref:`PoolVector3Array <class_PoolVector3Array>`.
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