brick-framework/GameCore/Movement/RotationSystem.cs

using GameCore.ECS;
using GameCore.ECS.Interfaces;
using GameCore.Input;
using GameCore.Player;

namespace GameCore.Movement;

public class RotationSystem : ISystem
{
    private const float MinPitch = -(float)System.Math.PI / 2f;
    private const float MaxPitch = (float)System.Math.PI / 2f;

    public void Update(World world, float deltaTime)
    {
        var entities = world.GetEntitiesWith<InputStateComponent>();
        foreach (var entity in entities)
        {
            var input = world.GetComponent<InputStateComponent>(entity);
            var rotation = world.GetComponent<RotationComponent>(entity);

            if (input == null || rotation == null)
            {
                world.Logger.Warn("RotationSystem: Missing InputStateComponent or RotationComponent.");
                continue;
            }

            if (world.GetComponent<PlayerComponent>(entity) != null)
            {
                rotation.Rotation.Y += input.LookDirection.Y;
                rotation.Rotation.X += input.LookDirection.X;
            }
            else
            {
                if (input.LookDirection.Length() > 0.001f)
                {
                    var lookDir = input.LookDirection;
                    rotation.Rotation.Y = (float)System.Math.Atan2(lookDir.X, lookDir.Z);

                    var horizontalDist = (float)System.Math.Sqrt(lookDir.X * lookDir.X + lookDir.Z * lookDir.Z);
                    rotation.Rotation.X = -(float)System.Math.Atan2(lookDir.Y, horizontalDist);
                }
            }


            rotation.Rotation.X = System.Math.Clamp(rotation.Rotation.X, MinPitch, MaxPitch);
        }
    }
}