Add tile entity occlusion (#14626)

Content.Client/Movement/Systems/FloorOcclusionSystem.cs

@@ -0,0 +1,55 @@
+using Content.Shared.Movement.Components;
+using Content.Shared.Movement.Systems;
+using Robust.Client.GameObjects;
+using Robust.Client.Graphics;
+using Robust.Shared.Prototypes;
+
+namespace Content.Client.Movement.Systems;
+
+public sealed class FloorOcclusionSystem : SharedFloorOcclusionSystem
+{
+    [Dependency] private readonly IPrototypeManager _proto = default!;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+        SubscribeLocalEvent<FloorOcclusionComponent, ComponentStartup>(OnOcclusionStartup);
+        SubscribeLocalEvent<FloorOcclusionComponent, AfterAutoHandleStateEvent>(OnOcclusionAuto);
+    }
+
+    private void OnOcclusionAuto(EntityUid uid, FloorOcclusionComponent component, ref AfterAutoHandleStateEvent args)
+    {
+        SetEnabled(uid, component, component.Enabled);
+    }
+
+    private void OnOcclusionStartup(EntityUid uid, FloorOcclusionComponent component, ComponentStartup args)
+    {
+        if (component.Enabled && TryComp<SpriteComponent>(uid, out var sprite))
+            SetShader(sprite, true);
+    }
+
+    protected override void SetEnabled(EntityUid uid, FloorOcclusionComponent component, bool enabled)
+    {
+        if (component.Enabled == enabled)
+            return;
+
+        base.SetEnabled(uid, component, enabled);
+
+        if (!TryComp<SpriteComponent>(uid, out var sprite))
+            return;
+
+        SetShader(sprite, enabled);
+    }
+
+    private void SetShader(SpriteComponent sprite, bool enabled)
+    {
+        if (enabled)
+        {
+            sprite.PostShader = _proto.Index<ShaderPrototype>("HorizontalCut").Instance();
+        }
+        else
+        {
+            sprite.PostShader = null;
+        }
+    }
+}

Content.Server/Movement/Systems/FloorOcclusionSystem.cs

@@ -0,0 +1,8 @@
+using Content.Shared.Movement.Systems;
+
+namespace Content.Server.Movement.Systems;
+
+public sealed class FloorOcclusionSystem : SharedFloorOcclusionSystem
+{
+
+}

Content.Shared/Movement/Components/FloorOccluderComponent.cs

@@ -0,0 +1,12 @@
+using Robust.Shared.GameStates;
+
+namespace Content.Shared.Movement.Components;
+
+/// <summary>
+/// Applies floor occlusion to any <see cref="FloorOcclusionComponent"/> that intersect us.
+/// </summary>
+[RegisterComponent, NetworkedComponent]
+public sealed partial class FloorOccluderComponent : Component
+{
+
+}

Content.Shared/Movement/Components/FloorOcclusionComponent.cs

@@ -0,0 +1,19 @@
+using Robust.Shared.GameStates;
+
+namespace Content.Shared.Movement.Components;
+
+/// <summary>
+/// Applies an occlusion shader to this entity if it's colliding with a <see cref="FloorOccluderComponent"/>
+/// </summary>
+[RegisterComponent, NetworkedComponent, AutoGenerateComponentState(true)]
+public sealed partial class FloorOcclusionComponent : Component
+{
+    /// <summary>
+    /// Is the shader currently enabled.
+    /// </summary>
+    [ViewVariables(VVAccess.ReadWrite), DataField("enabled"), AutoNetworkedField]
+    public bool Enabled;
+
+    [DataField("colliding")]
+    public List<EntityUid> Colliding = new();
+}

Content.Shared/Movement/Systems/SharedFloorOcclusionSystem.cs

@@ -0,0 +1,53 @@
+using Content.Shared.Movement.Components;
+using Robust.Shared.Physics.Events;
+
+namespace Content.Shared.Movement.Systems;
+
+/// <summary>
+/// Applies an occlusion shader for any relevant entities.
+/// </summary>
+public abstract class SharedFloorOcclusionSystem : EntitySystem
+{
+    public override void Initialize()
+    {
+        base.Initialize();
+        SubscribeLocalEvent<FloorOccluderComponent, StartCollideEvent>(OnStartCollide);
+        SubscribeLocalEvent<FloorOccluderComponent, EndCollideEvent>(OnEndCollide);
+    }
+
+    private void OnStartCollide(EntityUid uid, FloorOccluderComponent component, ref StartCollideEvent args)
+    {
+        var other = args.OtherEntity;
+
+        if (!TryComp<FloorOcclusionComponent>(other, out var occlusion) ||
+            occlusion.Colliding.Contains(uid))
+        {
+            return;
+        }
+
+        SetEnabled(other, occlusion, true);
+        occlusion.Colliding.Add(uid);
+    }
+
+    private void OnEndCollide(EntityUid uid, FloorOccluderComponent component, ref EndCollideEvent args)
+    {
+        var other = args.OtherEntity;
+
+        if (!TryComp<FloorOcclusionComponent>(other, out var occlusion))
+            return;
+
+        occlusion.Colliding.Remove(uid);
+
+        if (occlusion.Colliding.Count == 0)
+            SetEnabled(other, occlusion, false);
+    }
+
+    protected virtual void SetEnabled(EntityUid uid, FloorOcclusionComponent component, bool enabled)
+    {
+        if (component.Enabled == enabled)
+            return;
+
+        component.Enabled = enabled;
+        Dirty(uid, component);
+    }
+}

Resources/Prototypes/Entities/Mobs/Species/base.yml

@@ -5,6 +5,7 @@
   id: BaseMobOrganic
   noSpawn: true
   components:
+  - type: FloorOcclusion
   - type: LagCompensation
   - type: RangedDamageSound
     soundGroups:

Resources/Prototypes/Entities/Tiles/water.yml

@@ -7,9 +7,7 @@
     snap:
     - Wall
   components:
-  - type: StepTrigger
-    requiredTriggeredSpeed: 0
-    intersectRatio: 0.1
+  - type: FloorOccluder
   - type: Transform
     anchored: true
   - type: SyncSprite

Resources/Prototypes/Shaders/shaders.yml

@@ -76,3 +76,9 @@
   id: PaperStamp
   kind: source
   path: "/Textures/Shaders/paperstamp.swsl"
+  
+# Simple horizontal cut
+- type: shader
+  id: HorizontalCut
+  kind: source
+  path: "/Textures/Shaders/hcut.swsl"

Resources/Textures/Shaders/hcut.swsl

@@ -0,0 +1,13 @@
+light_mode unshaded;
+
+const highp float c = 0.3;
+const highp float alphaModifier = 0.2;
+uniform bool below = true;
+
+void fragment()
+{
+    highp vec4 tex = zTexture(UV);
+    highp float modifier = (UV.y > c ^^ !below) ? 1 : alphaModifier;
+
+    COLOR = vec4(tex.x, tex.y, tex.z, tex.w * modifier);
+}