// MonoBehaviour is the base class from which every Unity script derives.
// Offers some life cycle functions that are easier for you to develop your game.

// Some of the most frequently used ones are as follows;
Awake()
Start()
Update()
FixedUpdate()
LateUpdate()
OnGUI()
OnEnable()
OnDisable()

// Every object in a Scene has a Transform.
// It's used to store and manipulate the position, rotation and scale of the object.

transform.position.x = 0;

// Vector3 is representation of 3D vectors and points
// It's used to represent 3D positions,considering x,y & z axis.

Vector3 v = new Vector3(0f, 0f, 0f);

// A Quaternion stores the rotation of the Transform in world space.
// Quaternions are based on complex numbers and don't suffer from gimbal lock.
// Unity internally uses Quaternions to represent all rotations.
// You almost never access or modify individual Quaternion components (x,y,z,w); 

// A rotation 30 degrees around the y-axis
Quaternion rotation = Quaternion.Euler(0, 30, 0);

// Euler angles are "degree angles" like 90, 180, 45, 30 degrees.
// Quaternions differ from Euler angles in that they represent a point on a Unit Sphere (the radius is 1 unit).

// Create a quaternion that represents 30 degrees about X, 10 degrees about Y
Quaternion rotation = Quaternion.Euler(30, 10, 0);

// Using a Vector
Vector3 EulerRotation = new Vector3(30, 10, 0);
Quaternion rotation = Quaternion.Euler(EulerRotation);

// Convert a transform's Quaternion angles to Euler angles
Quaternion quaternionAngles = transform.rotation;
Vector3 eulerAngles = quaternionAngles.eulerAngles;

// Moves the transform in the direction and distance of translation.
public void Translate(Vector3 translation);
public void Translate(Vector3 translation, Space relativeTo = Space.Self);

transform.Translate(Vector3.right * movementSpeed);

// Calculate a position between the points specified by current and target
// Moving no farther than the distance specified by maxDistanceDelta
public static Vector3 MoveTowards(Vector3 current, Vector3 target, float maxDistanceDelta);

Vector3 targetPosition;
transform.position = Vector3.MoveTowards(transform.position, targetPosition, Time.deltaTime);

// Linearly interpolates between two points. Results in a smooth transition.
public static Vector3 Lerp(Vector3 startValue, Vector3 endValue, float interpolationRatio);

Vector3 targetPosition;
float t = 0;
t += Time.deltaTime * speed;
transform.position = Vector3.Lerp(transform.position, targetPosition, t);

// Gradually changes a vector towards a desired goal over time.
// The vector is smoothed by some spring-damper like function, which will never overshoot.
// The most common use is for smoothing a follow camera.
public static Vector3 SmoothDamp(Vector3 current, Vector3 target, ref Vector3 currentVelocity, float smoothTime, float maxSpeed = Mathf.Infinity, float deltaTime = Time.deltaTime);

float smoothTime = 1f;
Vector3 velocity;
Vector3 targetPosition = target.TransformPoint(new Vector3(0, 5, -10));
// Smoothly move the camera towards that target position
transform.position = Vector3.SmoothDamp(transform.position, targetPosition, ref velocity, smoothTime);

// A Quaternion stores the rotation of the Transform in world space.
// Quaternions are based on complex numbers and don't suffer from gimbal lock.
// Unity internally uses Quaternions to represent all rotations.

transform.rotation = new Quaternion(rotx, roty, rotz, rotw);

// Transform.eulerAngles represents rotation in world space. 
// It is important to understand that although you are providing X, Y, and Z rotation values to describe your rotation
// those values are not stored in the rotation. Instead, the X, Y & Z values are converted to the Quaternion's internal format.

transform.eulerAngles = Vector3(rotx, roty, rotz);

// Applies rotation around all the given axes.
public void Rotate(Vector3 eulers, Space relativeTo = Space.Self);
public void Rotate(float xAngle, float yAngle, float zAngle, Space relativeTo = Space.Self);

transform.Rotate(rotx, roty, rotz);

// Rotates the transform about axis passing through point in world coordinates by angle degrees.
public void RotateAround(Vector3 point, Vector3 axis, float angle);

// Spin the object around the target at 20 degrees/second.
Transform target;
transform.RotateAround(target.position, Vector3.up, 20 * Time.deltaTime);

// Points the positive 'Z' (forward) side of an object at a position in world space.
public void LookAt(Transform target);
public void LookAt(Transform target, Vector3 worldUp = Vector3.up);

// Rotate the object's forward vector to point at the target Transform.
Transform target;
transform.LookAt(target);

// Same as above, but setting the worldUp parameter to Vector3.left in this example turns the object on its side.
transform.LookAt(target, Vector3.left);

// Creates a rotation with the specified forward and upwards directions.
public static Quaternion LookRotation(Vector3 forward, Vector3 upwards = Vector3.up);

// The following code rotates the object towards a target object.
Vector3 direction = target.position - transform.position;
Quaternion rotation = Quaternion.LookRotation(direction);
transform.rotation = rotation;

// Creates a rotation (a Quaternion) which rotates from fromDirection to toDirection.
public static Quaternion FromToRotation(Vector3 fromDirection, Vector3 toDirection);

// Sets the rotation so that the transform's y-axis goes along the z-axis.
transform.rotation = Quaternion.FromToRotation(Vector3.up, transform.forward);

// Converts a rotation to angle-axis representation (angles in degrees).
// In other words, extracts the angle as well as the axis that this quaternion represents.
public void ToAngleAxis(out float angle, out Vector3 axis);

// Extracts the angle - axis rotation from the transform rotation
float angle = 0.0f;
Vector3 axis = Vector3.zero;
transform.rotation.ToAngleAxis(out angle, out axis);

void FixedUpdate() {
    // Bit shift the index of the layer (8) to get a bit mask
    int layerMask = 1 << 8;

    // This would cast rays only against colliders in layer 8.
    // But instead we want to collide against everything except layer 8. The ~ operator does this, it inverts a bitmask.
    layerMask = ~layerMask;

    RaycastHit hit;
    // Does the ray intersect any objects excluding the player layer
    if (Physics.Raycast(transform.position, transform.TransformDirection(Vector3.forward), out hit, Mathf.Infinity, layerMask)) {
        Debug.DrawRay(transform.position, transform.TransformDirection(Vector3.forward) * hit.distance, Color.yellow);
        Debug.Log("Did Hit");
    }
}

// Makes the collision detection system ignore all collisions between collider1 and collider2.
public static void IgnoreCollision(Collider collider1, Collider collider2, bool ignore = true);

// Here we're disabling the collision detection between the colliders of ally and bullet objects.
Transform bullet;
Transform ally;
Physics.IgnoreCollision(bullet.GetComponent<Collider>(), ally.GetComponent<Collider>());

// Returns true during the frame the user starts pressing down the key
if (Input.GetKeyDown(KeyCode.Space)) {
    Debug.Log("Space key was pressed");
}

// Jump is also set to space in Input Manager
if (Input.GetButtonDown("Jump")) {
    Debug.Log("Do something");
}

if (Input.GetAxis("Mouse X") < 0) {
    Debug.Log("Mouse moved left");
}

if (Input.GetAxis("Mouse Y") > 0) {
    Debug.Log("Mouse moved up");
}

if (Input.GetMouseButtonDown(0)) {
    Debug.Log("Pressed primary button.");
}

if (Input.GetMouseButtonDown(1)) {
    Debug.Log("Pressed secondary button.");
}

if (Input.GetMouseButtonDown(2)) {
    Debug.Log("Pressed middle click.");
}

if (Input.touchCount > 0) {
    touch = Input.GetTouch(0);

    if (touch.phase == TouchPhase.Began) {
        Debug.Log("Touch began");
    }

    if (touch.phase == TouchPhase.Moved) {
        Debug.Log("Touch moves");
    }

    if (touch.phase == TouchPhase.Ended) {
        Debug.Log("Touch ended");
    }
}

public class PlayAudio : MonoBehaviour {
    public AudioSource audioSource;

    void Start() {
        // Calling Play on an Audio Source that is already playing will make it start from the beginning
        audioSource.Play();
    }
}

// Define singleton class
public class SingletonClass: MonoBehaviour {
    private static SomeClass instance;

    public static SomeClass Instance { get { return instance; } }

    private void Awake() {
        if (instance != null && instance != this) {
            Destroy(this.gameObject);
        } else {
            instance = this;
        }
    }
}

// Use it in another class
public class AnotherClass: MonoBehaviour {
    public Singleton instance;

    private void Awake() {
       instance = Singleton.Instance;
    }
}

RaycastHit hit;

// Unlike this example, most of the time you should pass a layerMask as the last option to hit only to the ground
if (Physics.Raycast(transform.position, -Vector3.up, out hit, 0.5f)) {
   Debug.log("Hit something below!");
}

Animator animator;

Transform transform = animator.GetBoneTransform(HumanBodyBones.Head);

var camPosition = Camera.main.transform.position;

transform.rotation = Quaternion.LookRotation(transform.position - camPosition);

var nextSceneToLoad = SceneManager.GetActiveScene().buildIndex + 1;
var totalSceneCount = SceneManager.sceneCountInBuildSettings;

if (nextSceneToLoad < totalSceneCount) {
  SceneManager.LoadScene(nextSceneToLoad);
}