PlayerMovement .cs

using FlaxEngine;

namespace Game
{
    /// <summary>
    /// PlayerMovement Script.
    /// </summary>
    public class PlayerMovement : Script
    {
        [Serialize, ShowInEditor] private float _maxWalkSpeed;
        [Serialize, ShowInEditor] private float _accelerationTime;
        [Serialize, ShowInEditor] private float _decelerationTime;
        [Serialize, ShowInEditor] private float _upGravity = 0.8f;
        [Serialize, ShowInEditor] private float _downGravity = 1.0f;
        [Serialize, ShowInEditor] private float _jumpVelocity = 100;
        [Serialize, ShowInEditor] private float _minVelocity = 2f;
        [Serialize, ShowInEditor] private float _airControl = 0.5f;
        
        [Space(20)]
        [Serialize, ShowInEditor] private CharacterController _characterController;
        [Serialize, ShowInEditor] private Actor _playerCamera;
        [Serialize, ShowInEditor] private Actor _graphic;
        [Serialize, ShowInEditor] private AnimatedModel _animator;
        

        private AnimGraphParameter _walkSpeedParam;
        private AnimGraphParameter _jumpParam;
        private AnimGraphParameter _groundedParam;
        private float _verticalVelocity;
        private Vector3 _velocity;
        private Vector2 _input;

        /// <inheritdoc/>
        public override void OnAwake()
        {
            _walkSpeedParam = _animator.GetParameter("WalkSpeed");
            _jumpParam = _animator.GetParameter("Jump");
            _groundedParam = _animator.GetParameter("Grounded");
        }

        public override void OnUpdate()
        {
            _input = new Vector2(Input.GetAxis("Horizontal"), Input.GetAxis("Vertical"));
        }
        
        /// <inheritdoc/>
        public override void OnFixedUpdate()
        {
            Movement();
            Rotation();
        }

        private void Movement()
        {
            var deltaTime = 1 / Time.PhysicsFPS;
            
            // Velocity
            var forward = _playerCamera.Transform.Forward;
            var right = _playerCamera.Transform.Right;

            forward *= _input.Y;
            right *= _input.X;

            float control = 1;
            if (!_characterController.IsGrounded)
            {
                control = _airControl;
            }
            
            // Accelerate
            _velocity += (forward + right) * _maxWalkSpeed / _accelerationTime * deltaTime * control;
            
            // Decelerate
            if (_input.LengthSquared < 0.1f && _velocity.LengthSquared > _minVelocity * _minVelocity)
            {
                var deceleration = _velocity.Normalized * _maxWalkSpeed / _decelerationTime * deltaTime;
                _velocity -= deceleration;
            }

            _velocity = Vector3.ClampLength(_velocity, _maxWalkSpeed);
            
            if (_velocity.LengthSquared < _minVelocity * _minVelocity && 
                _input.LengthSquared < 0.1f)
            {
                _velocity = Vector3.Zero;
            }

            // Animation
            var walkAnimationSpeed = _velocity.Length * 0.1f;
            _walkSpeedParam.Value = walkAnimationSpeed;
            _groundedParam.Value = _characterController.IsGrounded;
            
            // Vertical velocity
            if (_characterController.IsGrounded && _verticalVelocity < 0)
            {
                _verticalVelocity = 0;
                _jumpParam.Value = false;
            }

            if (_verticalVelocity > 0)
            {
                _verticalVelocity -= _upGravity * deltaTime * 100;
            }
            else
            {
                _verticalVelocity -= _downGravity * deltaTime * 100;
            }

            if (_characterController.IsGrounded && Input.GetKeyDown(KeyboardKeys.Spacebar))
            {
                _verticalVelocity = _jumpVelocity;
                _jumpParam.Value = true;
            }

            // Move
            _characterController.Move(_velocity * deltaTime * 60 + _verticalVelocity * Vector3.Up);
        }

        private void Rotation()
        {
            if (_velocity.LengthSquared > 0.1f)
            {
                var angle = Mathf.Atan2(_velocity.X, _velocity.Z) * Mathf.RadiansToDegrees;
                var rotation = Matrix.RotationQuaternion(Quaternion.Euler(new Vector3(0, angle, 0)));
                _graphic.Rotation = rotation;
            }
        }
    }
}