TheMuseumProject/Assets/Scripts/Player/Movement/PlayerPhysics.cs

using Player.Interactions;
using UnityEngine;
using Player.Information;
namespace Player.Movement
{
    public class PlayerPhysics : MonoBehaviour
    {
        // measured in meters per second squared
        [SerializeField] private Vector3 gravity;

        [SerializeField] private float walkingForce;

        [SerializeField] private float maxWalkSpeed;

        [SerializeField] private float maxRunSpeed;

        // measured in N applied when space is pressed
        [SerializeField] private float jumpForce;

        [SerializeField] private float defaultAirControl;

        // the minimum change in speed which will result in damage being taken
        [SerializeField] private float speedDamageThreshold;

        // the ratio of speed change to damage taken
        [SerializeField] private float speedToDamage;


        // measured in seconds
        [SerializeField] private float coyoteTime;

        [SerializeField] private float jumpBuffer;

        // current air control ratio experienced by the player
        private float airControl;
        private float coyoteTimeCounter;


        // reference to GrappleHook script
        private GrappleHook grappleHook;

        // reference to JetPack script
        private JetPack jetPack;
        private float jumpBufferCounter;

        // current maximum input speed of the player
        private float maxSpeed;

        // referendce to PlayerStats script
        private PlayerStats playerStats;

        // metrics for ground detection
        //private float playerHeight;
        //private Vector3 boxDim;

        // speed of the player in the previous frame
        private float prevFrameSpeed;

        private Rigidbody rb;

        public void Reset()
        {
            prevFrameSpeed = 0f;
            rb.velocity = Vector3.zero;
            grappleHook.ReleaseGrapple();
            jetPack.ResetThrust();
        }

        // Start is called before the first frame update
        private void Start()
        {
            rb = gameObject.GetComponent<Rigidbody>();

            // ground detection constants
            //playerHeight = (transform.localScale.y / 2f);
            //Vector3 boxDim = transform.localScale;
            //boxDim = new Vector3(boxDim.x - 0.5f, boxDim.y + 0.5f, boxDim.z - 0.5f);

            maxSpeed = maxWalkSpeed;
            airControl = defaultAirControl;

            grappleHook = gameObject.GetComponent<GrappleHook>();
            jetPack = gameObject.GetComponent<JetPack>();
            playerStats = gameObject.GetComponent<PlayerStats>();
            prevFrameSpeed = 0f;
        }

        // Update is called once per frame
        private void Update()
        {
            var grounded = isGrounded();

            // coyote time manager
            if (grounded)
                coyoteTimeCounter = coyoteTime;
            else
                coyoteTimeCounter -= Time.deltaTime;

            // jump buffer manager
            if (Input.GetButtonDown("Jump") )
                jumpBufferCounter = jumpBuffer;
            else
                jumpBufferCounter -= Time.deltaTime;

            //Debug.Log("Coyote: " + coyoteTimeCounter + ". Buffer: " + jumpBufferCounter);

            // if jump key is pressed
            if (coyoteTimeCounter > 0f && jumpBufferCounter > 0f)
            {
                Debug.Log("jump");
                // apply an upward force to the player
                rb.AddForce(new Vector3(0f, jumpForce, 0f));

                coyoteTimeCounter = 0f;
                jumpBufferCounter = 0f;
            }

            // change current max speed depending on sprinting or not
            if (Input.GetKey(KeyCode.LeftShift) && grounded )
                maxSpeed = maxRunSpeed;
            else
                maxSpeed = maxWalkSpeed;
        }

        private void FixedUpdate()
        {
            // get the input values for player movement
            var movement = GetMoveInputs();
            // calculate the velocity change of the player based on input
            movement = movement.normalized * walkingForce;

            // scale movement force if not on ground
            if (!isGrounded()) movement *= airControl;

            var relativeMove = transform.right * movement.x + transform.forward * movement.z;
            var flatCurVelocity = Vector3.ProjectOnPlane(rb.velocity, transform.up);

            // calculate the velocity the player would have when adding input velocity to it
            var nextVelocity = flatCurVelocity + relativeMove * Time.deltaTime;

            // check if the player's next velocity has a magnitude above walking speed
            if (nextVelocity.magnitude > maxSpeed)
            {
                // if the player is currently moving below their maxSpeed and trying to accelerate up to it
                if (flatCurVelocity.magnitude < maxSpeed)
                    // scale the player's next velocity to be equal to their maxSpeed
                    nextVelocity = nextVelocity.normalized * maxSpeed;
                else
                    // else, scale the player's next velocity to equal their current speed
                    nextVelocity = nextVelocity.normalized * flatCurVelocity.magnitude;
            }

            // set the player's current velocity to their next velocity in the xz-plane
            rb.velocity = new Vector3(nextVelocity.x, rb.velocity.y, nextVelocity.z);

            // apply the force of a potential grapple hook to the player
            rb.AddForce(grappleHook.PullForce(transform.position));

            // apply the force of a potential jetpack to the player
            rb.AddForce(jetPack.ThrustForce());

            // apply the force of gravity to the player
            rb.AddForce(gravity, ForceMode.Acceleration);

            // calculate the change in player speed this frame
            var deltaSpeed = Mathf.Abs(rb.velocity.magnitude - prevFrameSpeed);

            // apply force damage to player depending on change in speed
            if (deltaSpeed > speedDamageThreshold)
                //Debug.Log(deltaSpeed - speedDamageThreshold);
                playerStats.ChangeHealth(-speedToDamage * (deltaSpeed - speedDamageThreshold));
            // update speed record for next frame
            prevFrameSpeed = rb.velocity.magnitude;

            //Debug.Log(isGrounded());
        }

        private void OnTriggerEnter(Collider other)
        {
            var tp = other.gameObject.GetComponent<TraversalProperties>();
            if (tp != null && tp.lethalToEnter) playerStats.Respawn();
        }

        public Vector3 GetMoveInputs()
        {
            var xzMove = Vector3.zero;
            if (Input.GetKey(KeyCode.W)) xzMove.z += 1f;
            if (Input.GetKey(KeyCode.S)) xzMove.z += -1f;
            if (Input.GetKey(KeyCode.D)) xzMove.x += 1f;
            if (Input.GetKey(KeyCode.A)) xzMove.x += -1f;
            return xzMove;
        }

        public bool isGrounded()
        {
            // Raycast using ray
            //return Physics.Raycast(transform.position, -Vector3.up, playerHeight + 0.1f);

            // Raycast using box
            //Vector3 boxCenter = transform.position - new Vector3(0f, playerHeight, 0f);
            //return Physics.CheckBox(boxCenter, boxDim);

            // Raycast using box hardcoded
            var boxCenter = transform.position - new Vector3(0f, 0.5f, 0f);
            return Physics.CheckBox(boxCenter, new Vector3(0.25f, 0.52f, 0.25f));
        }
    }
}