Delta-v/Content.Client/Drunk/DrunkOverlay.cs

using Content.Shared.CCVar;
using Content.Shared.Drunk;
using Robust.Client.Graphics;
using Robust.Client.Player;
using Robust.Shared.Configuration;
using Robust.Shared.Enums;
using Robust.Shared.Prototypes;
using Robust.Shared.Timing;

namespace Content.Client.Drunk;

public sealed class DrunkOverlay : Overlay
{
    private static readonly ProtoId<ShaderPrototype> DrunkShader = "Drunk";

    [Dependency] private readonly IEntityManager _entityManager = default!;
    [Dependency] private readonly IPrototypeManager _prototypeManager = default!;
    [Dependency] private readonly IPlayerManager _playerManager = default!;
    [Dependency] private readonly IGameTiming _timing = default!;
    [Dependency] private readonly IConfigurationManager _configManager = default!;
    private readonly Shared.StatusEffectNew.StatusEffectsSystem _statusEffectsSystem;

    public override OverlaySpace Space => OverlaySpace.WorldSpace;
    public override bool RequestScreenTexture => true;
    private readonly ShaderInstance _drunkShader;

    public float CurrentBoozePower = 0.0f;
    // Starting phase for the rotation effect.
    // Needed so it doesn't always look the same for 0 motion.
    public float Phase = 0f;

    private const float VisualThreshold = 10.0f;
    private const float PowerDivisor = 250.0f;
    /// <remarks>
    /// This is a magic number based on my person preference of how quickly the bloodloss effect should kick in.
    /// It is entirely arbitrary, and you should change it if it sucks.
    /// Honestly should be refactored to be based on amount of blood lost but that's out of scope for what I'm doing atm.
    /// Also caps all booze visual effects to a max intensity of 100 seconds or 100 booze power.
    /// </remarks>
    private const float MaxBoozePower = 100f;

    private const float BoozePowerScale = 8f;

    private float _visualScale = 0f;
    private float _timeScale = 1f;
    private float _distortionScale = 1f;

    public DrunkOverlay()
    {
        IoCManager.InjectDependencies(this);
        _statusEffectsSystem = _entityManager.System<Shared.StatusEffectNew.StatusEffectsSystem>();
        _drunkShader = _prototypeManager.Index(DrunkShader).InstanceUnique();
        _configManager.OnValueChanged(CCVars.ReducedMotion, OnReducedMotionChanged, invokeImmediately: true);
    }

    private void OnReducedMotionChanged(bool reducedMotion)
    {
        _timeScale = reducedMotion ? 0.0f : 1.0f;
        _distortionScale = reducedMotion ? 4.0f : 1.0f; // Make the offset stronger to compensate the lack of motion.
    }

    protected override void FrameUpdate(FrameEventArgs args)
    {

        var playerEntity = _playerManager.LocalEntity;

        if (playerEntity == null)
            return;

        if (!_statusEffectsSystem.TryGetMaxTime<DrunkStatusEffectComponent>(playerEntity.Value, out var status))
            return;

        var time = status.Item2;

        var power = time == null ? MaxBoozePower : (float)Math.Min((time - _timing.CurTime).Value.TotalSeconds, MaxBoozePower);

        CurrentBoozePower += BoozePowerScale * (power - CurrentBoozePower) * args.DeltaSeconds / (power + 1);
    }

    protected override bool BeforeDraw(in OverlayDrawArgs args)
    {
        if (!_entityManager.TryGetComponent(_playerManager.LocalEntity, out EyeComponent? eyeComp))
            return false;

        if (args.Viewport.Eye != eyeComp.Eye)
            return false;

        _visualScale = BoozePowerToVisual(CurrentBoozePower);
        return _visualScale > 0;
    }

    protected override void Draw(in OverlayDrawArgs args)
    {
        if (ScreenTexture == null)
            return;

        var handle = args.WorldHandle;

        _drunkShader.SetParameter("SCREEN_TEXTURE", ScreenTexture);
        _drunkShader.SetParameter("boozePower", _visualScale);
        _drunkShader.SetParameter("timeScale", _timeScale);
        _drunkShader.SetParameter("distortionScale", _distortionScale);
        _drunkShader.SetParameter("phase", Phase);
        handle.UseShader(_drunkShader);
        handle.DrawRect(args.WorldBounds, Color.White);
        handle.UseShader(null);
    }

    /// <summary>
    ///     Converts the # of seconds the drunk effect lasts for (booze power) to a percentage
    ///     used by the actual shader.
    /// </summary>
    /// <param name="boozePower"></param>
    private float BoozePowerToVisual(float boozePower)
    {
        // Clamp booze power when it's low, to prevent really jittery effects
        if (boozePower < 50f)
        {
            return 0;
        }
        else
        {
            return Math.Clamp((boozePower - VisualThreshold) / PowerDivisor, 0.0f, 1.0f);
        }
    }
}