CatStation/Content.Client/Flash/FlashOverlay.cs

using Content.Shared.CCVar;
using Content.Shared.Flash;
using Content.Shared.Flash.Components;
using Content.Shared.StatusEffectNew;
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.Flash;

public sealed partial class FlashOverlay : Overlay
{
    private static readonly ProtoId<ShaderPrototype> FlashedEffectShader = "FlashedEffect";

    [Dependency] private IPrototypeManager _prototypeManager = default!;
    [Dependency] private IEntityManager _entityManager = default!;
    [Dependency] private IPlayerManager _playerManager = default!;
    [Dependency] private IGameTiming _timing = default!;
    [Dependency] private IConfigurationManager _configManager = default!;

    private readonly StatusEffectsSystem _statusSys;

    public override OverlaySpace Space => OverlaySpace.WorldSpace;
    private readonly ShaderInstance _shader;
    private bool _reducedMotion;
    public float PercentComplete;
    public Texture? ScreenshotTexture;

    public FlashOverlay()
    {
        IoCManager.InjectDependencies(this);
        _shader = _prototypeManager.Index(FlashedEffectShader).InstanceUnique();
        _statusSys = _entityManager.System<StatusEffectsSystem>();

        _configManager.OnValueChanged(CCVars.DisableFlashEffect, (b) => { _reducedMotion = b; }, invokeImmediately: true);
    }

    protected override void FrameUpdate(FrameEventArgs args)
    {
        var playerEntity = _playerManager.LocalEntity;

        if (playerEntity == null)
            return;

        if (!_statusSys.HasEffectComp<FlashedStatusEffectComponent>(playerEntity))
            return;

        if (!_statusSys.TryGetTime(playerEntity.Value, SharedFlashSystem.FlashedKey, out var time))
            return;

        var curTime = _timing.CurTime;
        if (time.StartEffectTime == null || time.EndEffectTime == null)
            return;

        var lastsFor = (float)(time.EndEffectTime.Value - time.StartEffectTime.Value).TotalSeconds;
        var timeDone = (float)(curTime - time.StartEffectTime.Value).TotalSeconds;

        PercentComplete = timeDone / lastsFor;
    }

    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;

        return PercentComplete < 1.0f;
    }

    protected override void Draw(in OverlayDrawArgs args)
    {
        if (RequestScreenTexture && ScreenTexture != null)
        {
            ScreenshotTexture = ScreenTexture;
            RequestScreenTexture = false; // we only need the first frame, so we can stop the request now for performance reasons
        }
        if (ScreenshotTexture == null)
            return;

        var worldHandle = args.WorldHandle;
        if (_reducedMotion)
        {
            // TODO: This is a very simple placeholder.
            // Replace it with a proper shader once we come up with something good.
            // Turns out making an effect that is supposed to be a bright, sudden, and disorienting flash
            // not do any of that while also being equivalent in terms of game balance is hard.
            var alpha = 1 - MathF.Pow(PercentComplete, 8f); // similar falloff curve to the flash shader
            worldHandle.DrawRect(args.WorldBounds, new Color(0f, 0f, 0f, alpha));
        }
        else
        {
            _shader.SetParameter("percentComplete", PercentComplete);
            worldHandle.UseShader(_shader);
            worldHandle.DrawTextureRectRegion(ScreenshotTexture, args.WorldBounds);
        }
    }

    protected override void DisposeBehavior()
    {
        base.DisposeBehavior();
        ScreenshotTexture = null;
    }
}