Improve sprite fading behaviour (#35863)

* Click through faded sprites

* Count the mouse position for which sprites to fade

Content.Client/Sprite/SpriteFadeSystem.cs

@@ -1,8 +1,14 @@
+using System.Numerics;
 using Content.Client.Gameplay;
 using Content.Shared.Sprite;
 using Robust.Client.GameObjects;
+using Robust.Client.Input;
 using Robust.Client.Player;
 using Robust.Client.State;
+using Robust.Client.UserInterface.CustomControls;
+using Robust.Client.UserInterface;
+using Robust.Shared.Map;
+using Robust.Shared.Physics.Systems;
 using Robust.Shared.Physics;
 
 namespace Content.Client.Sprite;
@@ -17,6 +23,9 @@ public sealed class SpriteFadeSystem : EntitySystem
     [Dependency] private readonly IPlayerManager _playerManager = default!;
     [Dependency] private readonly IStateManager _stateManager = default!;
     [Dependency] private readonly SharedTransformSystem _transform = default!;
+    [Dependency] private readonly IUserInterfaceManager _uiManager = default!;
+    [Dependency] private readonly IInputManager _inputManager = default!;
+    [Dependency] private readonly SharedPhysicsSystem _physics = default!;
 
     private readonly HashSet<FadingSpriteComponent> _comps = new();
 
@@ -24,6 +33,11 @@ public sealed class SpriteFadeSystem : EntitySystem
     private EntityQuery<SpriteFadeComponent> _fadeQuery;
     private EntityQuery<FadingSpriteComponent> _fadingQuery;
 
+    /// <summary>
+    ///     Radius of the mouse point for the intersection test
+    /// </summary>
+    private static Vector2 MouseRadius = new Vector2(10f * float.Epsilon, 10f * float.Epsilon);
+
     private const float TargetAlpha = 0.4f;
     private const float ChangeRate = 1f;
 
@@ -46,46 +60,82 @@ public sealed class SpriteFadeSystem : EntitySystem
         sprite.Color = sprite.Color.WithAlpha(component.OriginalAlpha);
     }
 
-    public override void FrameUpdate(float frameTime)
+    /// <summary>
+    ///     Adds sprites to the fade set, and brings their alpha downwards
+    /// </summary>
+    private void FadeIn(float change)
     {
-        base.FrameUpdate(frameTime);
-
         var player = _playerManager.LocalEntity;
-        var change = ChangeRate * frameTime;
+        // ExcludeBoundingBox is set if we don't want to fade this sprite within the collision bounding boxes for the given POI
+        var pointsOfInterest = new List<(MapCoordinates Point, bool ExcludeBoundingBox)>();
 
-        if (TryComp(player, out TransformComponent? playerXform) &&
-            _stateManager.CurrentState is GameplayState state &&
-            _spriteQuery.TryGetComponent(player, out var playerSprite))
+        if (_uiManager.CurrentlyHovered is IViewportControl vp
+            && _inputManager.MouseScreenPosition.IsValid)
         {
-            var mapPos = _transform.GetMapCoordinates(_playerManager.LocalEntity!.Value, xform: playerXform);
+            pointsOfInterest.Add((vp.PixelToMap(_inputManager.MouseScreenPosition.Position), true));
+        }
 
-            // Also want to handle large entities even if they may not be clickable.
-            foreach (var ent in state.GetClickableEntities(mapPos))
+        if (TryComp(player, out TransformComponent? playerXform))
+        {
+            pointsOfInterest.Add((_transform.GetMapCoordinates(_playerManager.LocalEntity!.Value, xform: playerXform), false));
+        }
+
+        if (_stateManager.CurrentState is GameplayState state && _spriteQuery.TryGetComponent(player, out var playerSprite))
+        {
+            foreach (var (mapPos, excludeBB) in pointsOfInterest)
             {
-                if (ent == player ||
-                    !_fadeQuery.HasComponent(ent) ||
-                    !_spriteQuery.TryGetComponent(ent, out var sprite) ||
-                    sprite.DrawDepth < playerSprite.DrawDepth)
+                // Also want to handle large entities even if they may not be clickable.
+                foreach (var ent in state.GetClickableEntities(mapPos, excludeFaded: false))
                 {
-                    continue;
-                }
+                    if (ent == player ||
+                        !_fadeQuery.HasComponent(ent) ||
+                        !_spriteQuery.TryGetComponent(ent, out var sprite) ||
+                        sprite.DrawDepth < playerSprite.DrawDepth)
+                    {
+                        continue;
+                    }
 
-                if (!_fadingQuery.TryComp(ent, out var fading))
-                {
-                    fading = AddComp<FadingSpriteComponent>(ent);
-                    fading.OriginalAlpha = sprite.Color.A;
-                }
+                    if (excludeBB)
+                    {
+                        var test = new Box2Rotated(mapPos.Position - MouseRadius, mapPos.Position + MouseRadius);
+                        var collided = false;
+                        foreach (var fixture in _physics.GetCollidingEntities(mapPos.MapId, test))
+                        {
+                            if (fixture.Owner == ent)
+                            {
+                                collided = true;
+                                break;
+                            }
+                        }
+                        if (collided)
+                        {
+                            break;
+                        }
+                    }
 
-                _comps.Add(fading);
-                var newColor = Math.Max(sprite.Color.A - change, TargetAlpha);
+                    if (!_fadingQuery.TryComp(ent, out var fading))
+                    {
+                        fading = AddComp<FadingSpriteComponent>(ent);
+                        fading.OriginalAlpha = sprite.Color.A;
+                    }
 
-                if (!sprite.Color.A.Equals(newColor))
-                {
-                    sprite.Color = sprite.Color.WithAlpha(newColor);
+                    _comps.Add(fading);
+                    var newColor = Math.Max(sprite.Color.A - change, TargetAlpha);
+
+                    if (!sprite.Color.A.Equals(newColor))
+                    {
+                        sprite.Color = sprite.Color.WithAlpha(newColor);
+                    }
                 }
             }
         }
+    }
 
+    /// <summary>
+    ///     Bring sprites back up to their original alpha if they aren't in the fade set, and removes their fade component when done
+    /// </summary>
+    private void FadeOut(float change)
+    {
         var query = AllEntityQuery<FadingSpriteComponent>();
         while (query.MoveNext(out var uid, out var comp))
         {
@@ -106,6 +156,16 @@ public sealed class SpriteFadeSystem : EntitySystem
                 RemCompDeferred<FadingSpriteComponent>(uid);
             }
         }
+    }
+
+    public override void FrameUpdate(float frameTime)
+    {
+        base.FrameUpdate(frameTime);
+
+        var change = ChangeRate * frameTime;
+
+        FadeIn(change);
+        FadeOut(change);
 
         _comps.Clear();
     }