Add Boss Room educational content (#827)

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* Update docs/learn/bossroom/networkobject-parenting.md

Co-authored-by: Fernando Cortez <[email protected]>

* Update docs/learn/bossroom/networkobject-parenting.md

Co-authored-by: Fernando Cortez <[email protected]>

* Update docs/learn/bossroom/networkobject-parenting.md

Co-authored-by: Fernando Cortez <[email protected]>

* Update docs/learn/bossroom/networkrigidbody.md

Co-authored-by: Fernando Cortez <[email protected]>

* Update docs/learn/bossroom/networkrigidbody.md

Co-authored-by: Fernando Cortez <[email protected]>

Co-authored-by: Fernando Cortez <[email protected]>

Author: Larah Armstrong

docs/learn/bossroom/networkobject-parenting.md

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+---
+id: networkobject-parenting
+title: NetworkObject Parenting inside Boss Room
+description: Learn about Boss Room's approach to NetworkObject parenting.
+---
+:::note
+Required reading: [NetworkObject Parenting](../../advanced-topics/networkobject-parenting.md)
+:::
+
+Before detailing Boss Room’s approach toon `NetworkObject` parenting, it’s important to highlight a limitation of Netcode: A dynamically-spawned `NetworkObject` **cannot** contain another `NetworkObject` in its hierarchy. If you spawn such a `NetworkObject`, you cannot spawn children `NetworkObjects`. You can only add children `NetworkObject` components to a `NetworkObject` that is part of a scene.
+
+Boss Room leverages `NetworkObject` parenting through the server-driven `PickUp` action (see [`PickUpAction.cs`](https://github.com/Unity-Technologies/com.unity.multiplayer.samples.coop/blob/main/Assets/Scripts/Gameplay/Action/ConcreteActions/PickUpAction.cs)), where a character has the ability to pick up a specially-tagged, in-scene placed `NetworkObject` (see [`PickUpPot` prefab](https://github.com/Unity-Technologies/com.unity.multiplayer.samples.coop/blob/main/Assets/Prefabs/Game/PickUpPot.prefab)].
+
+At its root, `PickUpPot` contains a `NetworkObject`, a `NetworkTransform`, and a `PositionConstraint` component. `AutoObjectParentSync` is enabled on its `NetworkTransform` (as is by default) so that:
+
+1. The `NetworkObject` can verify server-side if parenting a Heavy object to another `NetworkObject` is allowed.
+2. The `NetworkObject` can notify us when the parent has successfully been modified server-side.
+
+To accommodate the limitation highlighted at the beginning of this document, Boss Room leverages the `PositionConstraint` component to simulate an object following a character’s position.
+
+A special hand bone has been added to our Character’s avatar. Upon a character’s successful parenting attempt, this special bone is set as the `PickUpPot`’s `PositonConstraint` target. So while the `PickUpPot` is technically parented to a player, the `PositionConstraint` component allows the `PickUpPot` to follow a bone’s position, presenting the **illusion** that the `PickUpPot` is parented to the player’s hand bone itself.
+
+Once the `PickUpPot` is parented, local space simulation is enabled on its [`NetworkTransform` component](../../components/networktransform.md).

docs/learn/bossroom/networkrigidbody.md

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+---
+id: networkrigidbody
+title: NetworkRigidbody inside Boss Room
+description: Learn how Boss Room leverages NetworkRigidbody.
+---
+:::note
+Required reading: [Physics](../..//advanced-topics/physics.md)
+:::
+
+Boss Room leverages `NetworkRigidbody` to simulate physics-based projectiles. See the Vandal Imp’s tossed projectile, the [`ImpTossedItem` prefab](https://github.com/Unity-Technologies/com.unity.multiplayer.samples.coop/blob/main/Assets/Prefabs/Game/ImpTossedItem.prefab). At its root, this prefab contains a `NetworkObject`, a `NetworkTransform`, a `Rigidbody`, and a `NetworkRigidbody` component. Refer to [`TossAction.cs`](https://github.com/Unity-Technologies/com.unity.multiplayer.samples.coop/blob/main/Assets/Scripts/Gameplay/Action/ConcreteActions/TossAction.cs) for more implementation details.
+
+An important note: Any modifications to a `Rigidbody` that involve Physics (that is, modifying velocity, applying forces, applying torque, and the like) must be done **after** the `NetworkObject` is spawned since `NetworkRigidbody` forces the Rigidbody’s `isKinematic` flag to be true on `Awake()`. Once spawned, this flag is modified depending on the ownership status of the `NetworkObject`.

docs/learn/bossroom/spawn-networkobjects.md

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+---
+id: spawn-networkobjects
+title: Dynamically spawning NetworkObjects in Boss Room to Resolve Zombie NetworkObjects
+description: Learn how to dynamically spawn NetworkObjects in Boss Room to resolve zombie NetworkObjects.
+---
+:::note
+Required reading: [Object Spawning](../../basics/object-spawning.md).
+:::
+
+This document serves as a walkthrough of Boss Room’s approach to solving the following issue: Late-joining clients entering networked sessions encountering zombie `NetworkObjects`. Zombie `NetworkObjects` represent `NetworkObjects` that are instantiated for a client due to scene loads but are not despawned or destroyed by Netcode.
+
+This is a particular Netcode limitation of `NetworkObject` spawning: `NetworkObjects` that belong to a scene object should not be destroyed until its scene has been unloaded through Netcode’s scene management.
+
+The scenario in question:
+
+* A host loads a scene and destroys a `NetworkObject` that belonged to that scene.
+* A client joins the host’s session and loads the additive scene. This operation loads **all** the `GameObjects` included in the additive scene. The `NetworkObject` that was destroyed on the server will not be destroyed on the client’s machine.
+
+This scenario manifested inside Boss Room, whereby late-joining clients joining a game session encountered zombie `NetworkObject`s that were not destroyed over the network.
+
+Additive scenes now contain prefab instances of a custom spawner, [`NetworkObjectSpawner`](https://github.com/Unity-Technologies/com.unity.multiplayer.samples.coop/blob/main/Packages/com.unity.multiplayer.samples.coop/Utilities/Net/NetworkObjectSpawner.cs) to accommodate this visual inconsistency.
+
+Compositionally, these additive scenes now only contain the following:
+
+* Prefab instances of level geometry.
+* Prefab instances of `NetworkObject`s that will **not** be despawned nor destroyed for the scene’s lifetime. Examples include [BreakablePot](https://github.com/Unity-Technologies/com.unity.multiplayer.samples.coop/blob/main/Assets/Prefabs/Game/BreakablePot.prefab) and [BreakableCrystal](https://github.com/Unity-Technologies/com.unity.multiplayer.samples.coop/blob/main/Assets/Prefabs/Game/BreakableCrystal.prefab).
+* Prefab instances of `NetworkObjectSpawner`, which spawn `NetworkObject`s that **may** be destroyed or despawned during the scene’s lifetime. Examples include [Imp](https://github.com/Unity-Technologies/com.unity.multiplayer.samples.coop/blob/main/Assets/GameData/Character/Imp/Imp.asset), [VandalImp](https://github.com/Unity-Technologies/com.unity.multiplayer.samples.coop/blob/main/Assets/GameData/Character/VandalImp/VandalImp.asset), and [ImpBoss](https://github.com/Unity-Technologies/com.unity.multiplayer.samples.coop/blob/main/Assets/GameData/Character/ImpBoss/ImpBoss.asset).

sidebars.js

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