Rotation arguments

The RotationArgument allows users to specify a pair of pitch and yaw coordinates. By default (using the ~ symbol), this refers to the player's current pitch and yaw of where they are looking at.

The RotationArgument class returns a Rotation object, which consists of the following methods:

Method name	What it does
`float getPitch()`	Returns a player's pitch (up and down rotation)
`float getYaw()`	Returns a player's yaw (left and right rotation)
`float getNormalizedPitch()`	Returns a player's pitch between -90 and 90 degrees
`float getNormalizedYaw()`	Returns a player's yaw between -180 and 180 degrees

Example: Rotate an armor stand head

Say we want to make an armor stand look in a certain direction. To do this, we'll use the following command:

/rotate <rotation> <target>

To do this, we'll use the rotation from the RotationArgument and select an entity using the EntitySelectorArgument, with EntitySelector.ONE_ENTITY. We then check if our entity is an armor stand and if so, we set its head pose to the given rotation.

LinkedHashMap<String, Argument> arguments = new LinkedHashMap<>();
arguments.put("rotation", new RotationArgument());
arguments.put("target", new EntitySelectorArgument(EntitySelector.ONE_ENTITY));

new CommandAPICommand("rotate")
    .withArguments(arguments)
    .executes((sender, args) -> {
        Rotation rotation = (Rotation) args[0];
        Entity target = (Entity) args[1];

        if(target instanceof ArmorStand) {
            ArmorStand a = (ArmorStand) target;
            a.setHeadPose(new EulerAngle(Math.toRadians(rotation.getPitch()), Math.toRadians(rotation.getYaw() - 90), 0));
        }
    })
    .register();

Note how the head pose requires an EulerAngle as opposed to a pitch and yaw. To account for this, we convert our rotation (which is in degrees) into an EulerAngle in radians.