API/Advanced/Custom-Mount-Controller.md

-WIP
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+A mount controller is a per-entity Modeled Entity movement controller that is required when mounting an entity to a
+model. By default, Model Engine provides 4 common controllers, but you can add your own to create custom controlling
+behavior. Read [this page](/Technical/Mount-Controllers) for more information on the default controllers.
+
+## Creating a controller class
+
+All controller class must implement `MountController` class, but you can also extend the `AbstractMountController`
+instead, which provides implementations on some basic and generic functionalities. In this example, we will
+use `AbstractMountController`.
+
+```java
+public class CustomMountController extends AbstractMountController {
+
+	// Type class used to specify the controller when mounting entity
+	// NEVER SUPPLY A STATIC INSTANCE
+	public static final MountControllerType CUSTOM = new MountControllerType(CustomMountController::new);
+
+	public CustomMountController(Entity entity, Mount mount) {
+		super(entity, mount);
+	}
+
+	@Override
+	public void updateDriverMovement(MoveController controller, ActiveModel model) {
+		// Update function for driver
+	}
+
+	@Override
+	public void updatePassengerMovement(MoveController controller, ActiveModel model) {
+		// Update function for passengers
+	}
+
+}
+```
+
+### Using MoveController
+
+The supplied `MoveController` object is a wrapper for the NMS `MoveControl` class. It contains numerous functions useful
+for controlling the entity, many of which calls back directly to the base NMS method.
+
+### Getting Inputs
+
+Inputs are updated every movement tick, and can be obtained through `getInput()` method. The returned object contains
+WASD, Jump and Sneak inputs.
+
+### Caveats
+
+In order for this system to work on most entities and have the movements be calculated correctly, while also altering
+Minecraft's default movement handling code as little as possible, the system will not work under these conditions:
+
+* The base entity is not a `Mob` (so armor stands will not work)
+* The base entity has no AI
+* The base entity never ticks
+
+## Using the controller
+
+Similar to mounting with default controllers, you mount with your own `MountControllerType`.
+
+```java
+ActiveModel model=...
+model.getMountManager().ifPresent(mountManager -> {
+	mountManager.mountDriver(entity, CustomMountController.CUSTOM);
+});
+```
+
+## Registering the controller
+
+While technically optional, it is generally advised to register your custom controller into
+the `MountControllerTypeRegistry` as this will allow you to use the controller with MythicMobs as well.
+
+```java
+// On plugin start-up
+ModelEngineAPI.getMountControllerTypeRegistry().register("custom_controller", CustomMountController.CUSTOM);
+```
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