Developing a first person controller for Unity3D with UniRx: Part 1

UniRxCharacterV1.cs

using UnityEngine;
using UniRx;
using UniRx.Triggers;

// NOTE: Unity won't actually let you put two MonoBehaviours in one file.
// They're both listed here just for convenience.

namespace Assets.Scripts.v1 {

	public class InputsV1 : MonoBehaviour {
		// Singleton.
		public static InputsV1 Instance { get; private set; }

		public IObservable<Vector2> Movement { get; private set; }
		public IObservable<Vector2> Mouselook { get; private set; }

		private void Awake() {
			Instance = this;

			// Hide the mouse cursor and lock it in the game window.
			Cursor.lockState = CursorLockMode.Locked;
			Cursor.visible = false;

			// Movement inputs tick on FixedUpdate
			Movement = this.FixedUpdateAsObservable()
				.Select(_ => {
					var x = Input.GetAxis("Horizontal");
					var y = Input.GetAxis("Vertical");
					return new Vector2(x, y).normalized;
				});

			// Mouse look ticks on Update
			Mouselook = this.UpdateAsObservable()
				.Select(_ => {
					var x = Input.GetAxis("Mouse X");
					var y = Input.GetAxis("Mouse Y");
					return new Vector2(x, y);
				});
		}
	}


	[RequireComponent(typeof(CharacterController))]
	public class PlayerControllerV1 : MonoBehaviour {

		public float walkSpeed = 5f;
		[Range(-90, 0)]
		public float minViewAngle = -60f; // How much can the user look down (in degrees)
		[Range(0, 90)]
		public float maxViewAngle = 60f; // How much can the user look up (in degrees)

		private CharacterController character;
		private Camera view;

		private void Awake() {
			character = GetComponent<CharacterController>();
			view = GetComponentInChildren<Camera>();
		}

		private void Start() {
			var inputs = InputsV1.Instance;

			// Handle movement input (WASD-style).
			inputs.Movement
				.Where(v => v != Vector2.zero) // We can ignore this if movement is zero.
				.Subscribe(inputMovement => {
					// Calculate velocity (direction * speed).
					var inputVelocity = inputMovement * walkSpeed;

					// Translate 2D velocity into 3D player coordinates.
					var playerVelocity =
						inputVelocity.x * transform.right + // x (+/-) corresponds to strafe right/left
						inputVelocity.y * transform.forward; // y (+/-) corresponds to forward/back

					// Apply movement.
					var distance = playerVelocity * Time.fixedDeltaTime;
					character.Move(distance);
				}).AddTo(this);

			// Handle mouse input (free mouse look).
			inputs.Mouselook
				.Where(v => v != Vector2.zero) // We can ignore this if mouse look is zero.
				.Subscribe(inputLook => {
					// Translate 2D mouse input into euler angle rotations.

					// inputLook.x rotates the character around the vertical axis (with + being right)
					var horzLook = inputLook.x * Time.deltaTime * Vector3.up;
					transform.localRotation *= Quaternion.Euler(horzLook);

					// inputLook.y rotates the camera around the horizontal axis (with + being up)
					var vertLook = inputLook.y * Time.deltaTime * Vector3.left;
					var newQ = view.transform.localRotation * Quaternion.Euler(vertLook);

					// We have to flip the signs and positions of min/max view angle here because the math
					// uses the contradictory interpretation of our angles (+/- is down/up).
					view.transform.localRotation = ClampRotationAroundXAxis(newQ, -maxViewAngle, -minViewAngle);
				}).AddTo(this);
		}

		// Ripped straight out of the Standard Assets MouseLook script. (This should really be a standard function...)
		private static Quaternion ClampRotationAroundXAxis(Quaternion q, float minAngle, float maxAngle) {
			q.x /= q.w;
			q.y /= q.w;
			q.z /= q.w;
			q.w = 1.0f;

			float angleX = 2.0f * Mathf.Rad2Deg * Mathf.Atan(q.x);

			angleX = Mathf.Clamp(angleX, minAngle, maxAngle);

			q.x = Mathf.Tan(0.5f * Mathf.Deg2Rad * angleX);

			return q;
		}
	}
}