voxel/Player.cs

using OpenTK.Mathematics;
using OpenTK.Windowing.Common;
using OpenTK.Windowing.GraphicsLibraryFramework;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading.Tasks;

namespace Voxel
{
    public class Player : Entity
    {
        public double lastClick = 0;
        public readonly float mouseCooldown = 0.2f;

        private int _blockIndex = 0;
        private double _tickTime = 0;

        private Blocks _selectedBlock = Blocks.OakPlanks;
        private Vector3 previousPosition;

        public Player(Vector3 startPos, World world) : base(startPos, 0.5f, 1.8f, world)
        {
            Input.OnMouseWheel += SwitchBlock;
        }

        public void PlaceBlock()
        {
            var (success, hit, x, y, z, normal) = _world.Raycast(Camera.Position, Camera.Front.Normalized(), 8);
            if (!success) return;

            x += normal.X;
            y += normal.Y;
            z += normal.Z;

            _world.SetBlock(x, y, z, _selectedBlock);
        }

        public void BreakBlock()
        {
            var (success, hit, x, y, z, normal) = _world.Raycast(Camera.Position, Camera.Front.Normalized(), 8);
            if (!success) return;

            _world.SetBlock(x, y, z, Blocks.Air);
        }

        public new void Tick()
        {
            previousPosition = Position;

            float forwards = 0;
            float sidewards = 0;

            if (Input.GetKey(Keys.W))
                forwards = -1;
            if (Input.GetKey(Keys.S))
                forwards = 1;
            if (Input.GetKey(Keys.A))
                sidewards = -1;
            if (Input.GetKey(Keys.D))
                sidewards = 1;

            if (Input.GetKey(Keys.Space) && OnGround)
            {
                Console.WriteLine("Jump");
                Velocity = new Vector3(Velocity.X, 0.42f, Velocity.Z);
                OnGround = false;
            }

            if (Input.GetMouseButton(MouseButton.Right) && lastClick == 0)
            {
                lastClick = mouseCooldown;

                PlaceBlock();
            }

            if (Input.GetMouseButton(MouseButton.Left) && lastClick == 0)
            {
                lastClick = mouseCooldown;

                BreakBlock();
            }

            ApplyWalkSpeed(sidewards, forwards);
            base.Tick();
        }

        public void Update(float deltaTime, float alpha)
        {
            Camera.Position = Vector3.Lerp(previousPosition, Position, alpha) + Vector3.UnitY * 0.62f;
            Rotation = Camera.Yaw;

            if (lastClick > 0)
            {
                lastClick -= deltaTime;
                if (lastClick < 0) lastClick = 0;
            }

            if (!Input.GetMouseButton(MouseButton.Right) && !Input.GetMouseButton(MouseButton.Left))
            {
                lastClick = 0;
            }
        }

        public void ApplyWalkSpeed(float x, float z)
        {
            Vector3 inputDir = new Vector3(x, 0, z);
            if (inputDir.LengthSquared > 0)
                inputDir = Vector3.Normalize(inputDir);

            float yawRad = MathHelper.DegreesToRadians(Rotation);
            float cos = MathF.Cos(yawRad);
            float sin = MathF.Sin(yawRad);

            Vector3 worldDir = new Vector3(
                inputDir.X * cos - inputDir.Z * sin,
                0,
                inputDir.X * sin + inputDir.Z * cos
            );

            float M_t = 1.4f;
            float groundMultiplier = 0.6f;

            if (!OnGround)
            {
                Vector3 airAccel = worldDir * 0.02f * M_t;
                Velocity = new Vector3(Velocity.X + airAccel.X, Velocity.Y, Velocity.Z + airAccel.Z);
            }
            else
            {
                Vector3 groundAccel = worldDir * 0.1f * M_t;
                Velocity = new Vector3(Velocity.X * groundMultiplier + groundAccel.X,
                              Velocity.Y,
                              Velocity.Z * groundMultiplier + groundAccel.Z);
            }
        }

        public void SwitchBlock(MouseWheelEventArgs e)
        {
            var keys = BlockDefinitions.Blocks.Keys.ToList();

            bool inverted = false;
            
            if (e.OffsetY < 0)
                inverted = true;

            if (inverted)
                if (_blockIndex == 0)
                    _blockIndex = keys.Count -1;
                else
                    _blockIndex -= 1;
            else
                _blockIndex += 1;

            _blockIndex = _blockIndex % keys.Count;
            _selectedBlock = keys[_blockIndex];
            Console.WriteLine(_selectedBlock);
        }
    }
}