Basic drug shader (#9033)

Content.Client/Drugs/RainbowOverlay.cs

@@ -0,0 +1,70 @@
+using Content.Shared.Drugs;
+using Content.Shared.StatusEffect;
+using Robust.Client.Graphics;
+using Robust.Client.Player;
+using Robust.Shared.Enums;
+using Robust.Shared.Prototypes;
+using Robust.Shared.Timing;
+
+namespace Content.Client.Drugs;
+
+public sealed class RainbowOverlay : Overlay
+{
+    [Dependency] private readonly IEntityManager _entityManager = default!;
+    [Dependency] private readonly IPrototypeManager _prototypeManager = default!;
+    [Dependency] private readonly IPlayerManager _playerManager = default!;
+    [Dependency] private readonly IEntitySystemManager _sysMan = default!;
+
+    public override OverlaySpace Space => OverlaySpace.WorldSpace;
+    public override bool RequestScreenTexture => true;
+    private readonly ShaderInstance _rainbowShader;
+
+    public float Intoxication = 0.0f;
+
+    private const float VisualThreshold = 10.0f;
+    private const float PowerDivisor = 250.0f;
+
+    private float EffectScale => Math.Clamp((Intoxication - VisualThreshold) / PowerDivisor, 0.0f, 1.0f);
+
+    public RainbowOverlay()
+    {
+        IoCManager.InjectDependencies(this);
+        _rainbowShader = _prototypeManager.Index<ShaderPrototype>("Rainbow").InstanceUnique();
+    }
+
+    protected override void FrameUpdate(FrameEventArgs args)
+    {
+        var playerEntity = _playerManager.LocalPlayer?.ControlledEntity;
+
+        if (playerEntity == null)
+            return;
+
+        if (!_entityManager.HasComponent<SeeingRainbowsComponent>(playerEntity)
+            || !_entityManager.TryGetComponent<StatusEffectsComponent>(playerEntity, out var status))
+            return;
+
+        var statusSys = _sysMan.GetEntitySystem<StatusEffectsSystem>();
+        if (!statusSys.TryGetTime(playerEntity.Value, DrugOverlaySystem.RainbowKey, out var time, status))
+            return;
+
+        var timeLeft = (float) (time.Value.Item2 - time.Value.Item1).TotalSeconds;
+        Intoxication += (timeLeft - Intoxication) * args.DeltaSeconds / 16f;
+    }
+
+    protected override bool BeforeDraw(in OverlayDrawArgs args)
+    {
+        return EffectScale > 0;
+    }
+
+    protected override void Draw(in OverlayDrawArgs args)
+    {
+        if (ScreenTexture == null)
+            return;
+
+        var handle = args.WorldHandle;
+        _rainbowShader.SetParameter("SCREEN_TEXTURE", ScreenTexture);
+        _rainbowShader.SetParameter("effectScale", EffectScale);
+        handle.UseShader(_rainbowShader);
+        handle.DrawRect(args.WorldBounds, Color.White);
+    }
+}