Newtonian Singularity (Simple-Station#1619)

# Description

By request from the very same person who assisted with
Simple-Station#1618
This PR ports(and fixes)
space-wizards/space-station-14#23372 such that
it works on modern Robust Toolbox.

This PR essentially makes it so that the Singularity (And Tesla by
extension) inherit some of the momentum of objects thrown into them. Im
practice it means that they now work more like they do in SS13, whereby
if a traitor does not actively intervene in a Singuloose(such as by
using a Singularity Beacon), the singularity will usually be "Blown back
into space" by space wind throwing objects at it in retaliation to it
eating engineering.

<details><summary><h1>Media</h1></summary>
<p>


https://github.com/user-attachments/assets/04e9e5b9-d873-4425-b19a-b854b57db486

</p>
</details>

# Changelog

:cl:
- add: Singularity and Tesla are now affected by objects thrown into
them, causing them to change directions. Unless a traitor intervenes
(with a Singularity Beacon), a "Singuloose" is extremely likely to be
blown out to space.

---------

Signed-off-by: VMSolidus <[email protected]>
Co-authored-by: DEATHB4DEFEAT <[email protected]>

Content.Server/Singularity/Components/GravityWellComponent.cs

@@ -67,5 +67,17 @@ public sealed partial class GravityWellComponent : Component
     [Access(typeof(GravityWellSystem))]
     public TimeSpan LastPulseTime { get; internal set; } = default!;
 
+    /// <summary>
+    ///     Whether to also apply Newton's third law.
+    /// </summary>
+    [DataField]
+    public bool ApplyCounterforce;
+
+    /// <summary>
+    ///     If <see cref="ApplyCounterforce"/> is true, how much to pull self to static objects. Does not pull static objects if null.
+    /// </summary>
+    [DataField]
+    public float? StaticAttraction = null;
+
     #endregion Update Timing
 }

Content.Server/Singularity/EntitySystems/EventHorizonSystem.cs

@@ -11,9 +11,11 @@
 using Robust.Shared.Containers;
 using Robust.Shared.Map;
 using Robust.Shared.Map.Components;
+using Robust.Shared.Physics.Components;
 using Robust.Shared.Physics.Events;
+using Robust.Shared.Physics.Systems;
 using Robust.Shared.Timing;
-using Content.Shared.Abilities.Psionics; //Nyano - Summary: for the telegnostic projection.
+using Content.Shared.Abilities.Psionics;
 
 namespace Content.Server.Singularity.EntitySystems;
 
@@ -29,6 +31,7 @@ public sealed class EventHorizonSystem : SharedEventHorizonSystem
     [Dependency] private readonly IMapManager _mapMan = default!;
     [Dependency] private readonly IAdminLogManager _adminLogger = default!;
     [Dependency] private readonly SharedContainerSystem _containerSystem = default!;
+    [Dependency] private readonly SharedPhysicsSystem _physics = default!;
     [Dependency] private readonly SharedTransformSystem _xformSystem = default!;
     [Dependency] private readonly TagSystem _tagSystem = default!;
     #endregion Dependencies
@@ -39,7 +42,7 @@ public override void Initialize()
 
         SubscribeLocalEvent<MapGridComponent, EventHorizonAttemptConsumeEntityEvent>(PreventConsume);
         SubscribeLocalEvent<GhostComponent, EventHorizonAttemptConsumeEntityEvent>(PreventConsume);
-        SubscribeLocalEvent<TelegnosticProjectionComponent, EventHorizonAttemptConsumeEntityEvent>(PreventConsume); ///Nyano - Summary: the telegnositic projection has the same trait as ghosts. 
+        SubscribeLocalEvent<TelegnosticProjectionComponent, EventHorizonAttemptConsumeEntityEvent>(PreventConsume); ///Nyano - Summary: the telegnositic projection has the same trait as ghosts.
         SubscribeLocalEvent<StationDataComponent, EventHorizonAttemptConsumeEntityEvent>(PreventConsume);
         SubscribeLocalEvent<EventHorizonComponent, MapInitEvent>(OnHorizonMapInit);
         SubscribeLocalEvent<EventHorizonComponent, StartCollideEvent>(OnStartCollide);
@@ -127,6 +130,15 @@ public void ConsumeEntity(EntityUid hungry, EntityUid morsel, EventHorizonCompon
         }
 
         EntityManager.QueueDeleteEntity(morsel);
+
+        if (eventHorizon.InheritMomentum && TryComp<PhysicsComponent>(hungry, out var thisPhysics) && TryComp<PhysicsComponent>(morsel, out var otherPhysics))
+        {
+            var impulse = (otherPhysics.LinearVelocity - thisPhysics.LinearVelocity)
+                * otherPhysics.FixturesMass
+                * thisPhysics.FixturesMass / (thisPhysics.FixturesMass + otherPhysics.FixturesMass); // Accounts for the expected mass change from consuming the object
+            _physics.ApplyLinearImpulse(hungry, impulse, body: thisPhysics);
+        }
+
         var evSelf = new EntityConsumedByEventHorizonEvent(morsel, hungry, eventHorizon, outerContainer);
         var evEaten = new EventHorizonConsumedEntityEvent(morsel, hungry, eventHorizon, outerContainer);
         RaiseLocalEvent(hungry, ref evSelf);

Content.Server/Singularity/EntitySystems/GravityWellSystem.cs

@@ -99,7 +99,10 @@ private void Update(EntityUid uid, TimeSpan frameTime, GravityWellComponent? gra
             return;
 
         var scale = (float)frameTime.TotalSeconds;
-        GravPulse(uid, gravWell.MaxRange, gravWell.MinRange, gravWell.BaseRadialAcceleration * scale, gravWell.BaseTangentialAcceleration * scale, xform);
+        GravPulse(uid, out var appliedImpulse, gravWell.MaxRange, gravWell.MinRange, gravWell.BaseRadialAcceleration * scale, gravWell.BaseTangentialAcceleration * scale, xform, gravWell.StaticAttraction);
+
+        if (gravWell.ApplyCounterforce && TryComp<PhysicsComponent>(uid, out var physics))
+            _physics.ApplyLinearImpulse(uid, -appliedImpulse, body: physics);
     }
 
     #region GravPulse
@@ -123,29 +126,36 @@ private bool CanGravPulseAffect(EntityUid entity)
     /// Greates a gravitational pulse, shoving around all entities within some distance of an epicenter.
     /// </summary>
     /// <param name="uid">The entity at the epicenter of the gravity pulse.</param>
+    /// <param name="gravWell">The state of the gravity well that is pulsing.</param>
     /// <param name="maxRange">The maximum distance at which entities can be affected by the gravity pulse.</param>
     /// <param name="minRange">The minimum distance at which entities can be affected by the gravity pulse.</param>
     /// <param name="baseMatrixDeltaV">The base velocity added to any entities within affected by the gravity pulse scaled by the displacement of those entities from the epicenter.</param>
     /// <param name="xform">(optional) The transform of the entity at the epicenter of the gravitational pulse.</param>
-    public void GravPulse(EntityUid uid, float maxRange, float minRange, in Matrix3x2 baseMatrixDeltaV, TransformComponent? xform = null)
+    public void GravPulse(EntityUid uid, out Vector2 appliedImpulse, float maxRange, float minRange, in Matrix3x2 baseMatrixDeltaV, TransformComponent? xform = null, float? staticImpulse = null)
     {
         if (Resolve(uid, ref xform))
-            GravPulse(xform.Coordinates, maxRange, minRange, in baseMatrixDeltaV);
+            GravPulse(uid, out appliedImpulse, xform.Coordinates, maxRange, minRange, in baseMatrixDeltaV, staticImpulse);
+        else
+            appliedImpulse = new Vector2(0f, 0f);
     }
 
+
     /// <summary>
     /// Greates a gravitational pulse, shoving around all entities within some distance of an epicenter.
     /// </summary>
     /// <param name="uid">The entity at the epicenter of the gravity pulse.</param>
+    /// <param name="gravWell">The state of the gravity well that is pulsing.</param>
     /// <param name="maxRange">The maximum distance at which entities can be affected by the gravity pulse.</param>
     /// <param name="minRange">The minimum distance at which entities can be affected by the gravity pulse.</param>
     /// <param name="baseRadialDeltaV">The base radial velocity that will be added to entities within range towards the center of the gravitational pulse.</param>
     /// <param name="baseTangentialDeltaV">The base tangential velocity that will be added to entities within countrclockwise around the center of the gravitational pulse.</param>
     /// <param name="xform">(optional) The transform of the entity at the epicenter of the gravitational pulse.</param>
-    public void GravPulse(EntityUid uid, float maxRange, float minRange, float baseRadialDeltaV = 0.0f, float baseTangentialDeltaV = 0.0f, TransformComponent? xform = null)
+    public void GravPulse(EntityUid uid, out Vector2 appliedImpulse, float maxRange, float minRange, float baseRadialDeltaV = 0.0f, float baseTangentialDeltaV = 0.0f, TransformComponent? xform = null, float? staticImpulse = null)
     {
         if (Resolve(uid, ref xform))
-            GravPulse(xform.Coordinates, maxRange, minRange, baseRadialDeltaV, baseTangentialDeltaV);
+            GravPulse(uid, out appliedImpulse, xform.Coordinates, maxRange, minRange, baseRadialDeltaV, baseTangentialDeltaV, staticImpulse);
+        else
+            appliedImpulse = new Vector2(0f, 0f);
     }
 
     /// <summary>
@@ -155,8 +165,8 @@ public void GravPulse(EntityUid uid, float maxRange, float minRange, float baseR
     /// <param name="maxRange">The maximum distance at which entities can be affected by the gravity pulse.</param>
     /// <param name="minRange">The minimum distance at which entities can be affected by the gravity pulse.</param>
     /// <param name="baseMatrixDeltaV">The base velocity added to any entities within affected by the gravity pulse scaled by the displacement of those entities from the epicenter.</param>
-    public void GravPulse(EntityCoordinates entityPos, float maxRange, float minRange, in Matrix3x2 baseMatrixDeltaV)
-        => GravPulse(entityPos.ToMap(EntityManager, _transform), maxRange, minRange, in baseMatrixDeltaV);
+    public void GravPulse(EntityUid uid, out Vector2 appliedImpulse, EntityCoordinates entityPos, float maxRange, float minRange, in Matrix3x2 baseMatrixDeltaV, float? staticImpulse = null)
+        => GravPulse(uid, out appliedImpulse, _transform.ToMapCoordinates(entityPos), maxRange, minRange, in baseMatrixDeltaV, staticImpulse);
 
     /// <summary>
     /// Greates a gravitational pulse, shoving around all entities within some distance of an epicenter.
@@ -166,18 +176,22 @@ public void GravPulse(EntityCoordinates entityPos, float maxRange, float minRang
     /// <param name="minRange">The minimum distance at which entities can be affected by the gravity pulse.</param>
     /// <param name="baseRadialDeltaV">The base radial velocity that will be added to entities within range towards the center of the gravitational pulse.</param>
     /// <param name="baseTangentialDeltaV">The base tangential velocity that will be added to entities within countrclockwise around the center of the gravitational pulse.</param>
-    public void GravPulse(EntityCoordinates entityPos, float maxRange, float minRange, float baseRadialDeltaV = 0.0f, float baseTangentialDeltaV = 0.0f)
-        => GravPulse(entityPos.ToMap(EntityManager, _transform), maxRange, minRange, baseRadialDeltaV, baseTangentialDeltaV);
+    public void GravPulse(EntityUid uid, out Vector2 appliedImpulse, EntityCoordinates entityPos, float maxRange, float minRange, float baseRadialDeltaV = 0.0f, float baseTangentialDeltaV = 0.0f, float? staticImpulse = null)
+        => GravPulse(uid, out appliedImpulse, _transform.ToMapCoordinates(entityPos), maxRange, minRange, baseRadialDeltaV, baseTangentialDeltaV, staticImpulse);
 
     /// <summary>
     /// Causes a gravitational pulse, shoving around all entities within some distance of an epicenter.
     /// </summary>
+    /// <param name="uid">The entity at the epicenter of the gravity pulse.</param>
+    /// <param name="gravWell">The state of the gravity well that is pulsing.</param>
     /// <param name="mapPos">The epicenter of the gravity pulse.</param>
     /// <param name="maxRange">The maximum distance at which entities can be affected by the gravity pulse.</param>
     /// <param name="minRange">The minimum distance at which entities can be affected by the gravity pulse. Exists to prevent div/0 errors.</param>
     /// <param name="baseMatrixDeltaV">The base velocity added to any entities within affected by the gravity pulse scaled by the displacement of those entities from the epicenter.</param>
-    public void GravPulse(MapCoordinates mapPos, float maxRange, float minRange, in Matrix3x2 baseMatrixDeltaV)
+    public void GravPulse(EntityUid uid, out Vector2 appliedImpulse, MapCoordinates mapPos, float maxRange, float minRange, in Matrix3x2 baseMatrixDeltaV, float? staticImpulse = null)
     {
+        appliedImpulse = new Vector2(0f, 0f);
+
         if (mapPos == MapCoordinates.Nullspace)
             return; // No gravpulses in nullspace please.
 
@@ -186,43 +200,57 @@ public void GravPulse(MapCoordinates mapPos, float maxRange, float minRange, in
         var bodyQuery = GetEntityQuery<PhysicsComponent>();
         var xformQuery = GetEntityQuery<TransformComponent>();
 
-        foreach(var entity in _lookup.GetEntitiesInRange(mapPos.MapId, epicenter, maxRange, flags: LookupFlags.Dynamic | LookupFlags.Sundries))
+        var countStatic = staticImpulse is not null;
+
+        var flags = LookupFlags.Dynamic | LookupFlags.Sundries;
+        if (countStatic)
+            flags |= LookupFlags.Static;
+
+        foreach(var entity in _lookup.GetEntitiesInRange(mapPos.MapId, epicenter, maxRange, flags: flags))
         {
-            if (!bodyQuery.TryGetComponent(entity, out var physics)
-                || physics.BodyType == BodyType.Static)
-            {
+            if (!bodyQuery.TryGetComponent(entity, out var physics))
                 continue;
-            }
-
-            if (TryComp<MovedByPressureComponent>(entity, out var movedPressure) && !movedPressure.Enabled) //Ignore magboots users
+            bool isStatic = physics.BodyType == BodyType.Static;
+            if (!countStatic && isStatic)
                 continue;
 
-            if(!CanGravPulseAffect(entity))
+            if (!CanGravPulseAffect(entity))
                 continue;
 
+            isStatic |= TryComp<MovedByPressureComponent>(entity, out var movedPressure) && !movedPressure.Enabled; // Treat magboots users as static
+
             var displacement = epicenter - _transform.GetWorldPosition(entity, xformQuery);
             var distance2 = displacement.LengthSquared();
             if (distance2 < minRange2)
                 continue;
 
-            var scaling = (1f / distance2) * physics.Mass; // TODO: Variable falloff gradiants.
-            _physics.ApplyLinearImpulse(entity, Vector2.Transform(displacement, baseMatrixDeltaV) * scaling, body: physics);
+            var scaling = (1f / distance2) * physics.FixturesMass; // TODO: Variable falloff gradients
+            if (isStatic)
+                scaling *= staticImpulse ?? 1f;
+
+            var impulse = Vector2.Transform(displacement, baseMatrixDeltaV) * scaling;
+            if (!isStatic) // Impulse shouldn't be applied to static entities
+                _physics.ApplyLinearImpulse(entity, impulse, body: physics);
+
+            appliedImpulse += impulse;
         }
     }
 
     /// <summary>
     /// Causes a gravitational pulse, shoving around all entities within some distance of an epicenter.
     /// </summary>
+    /// <param name="uid">The entity at the epicenter of the gravity pulse.</param>
+    /// <param name="gravWell">The state of the gravity well that is pulsing.</param>
     /// <param name="mapPos">The epicenter of the gravity pulse.</param>
     /// <param name="maxRange">The maximum distance at which entities can be affected by the gravity pulse.</param>
     /// <param name="minRange">The minimum distance at which entities can be affected by the gravity pulse. Exists to prevent div/0 errors.</param>
     /// <param name="baseRadialDeltaV">The base amount of velocity that will be added to entities in range towards the epicenter of the pulse.</param>
     /// <param name="baseTangentialDeltaV">The base amount of velocity that will be added to entities in range counterclockwise relative to the epicenter of the pulse.</param>
-    public void GravPulse(MapCoordinates mapPos, float maxRange, float minRange = 0.0f, float baseRadialDeltaV = 0.0f, float baseTangentialDeltaV = 0.0f)
-        => GravPulse(mapPos, maxRange, minRange, new Matrix3x2(
-            baseRadialDeltaV, -baseTangentialDeltaV, 0.0f,
-            +baseTangentialDeltaV, baseRadialDeltaV, 0.0f
-        ));
+    public void GravPulse(EntityUid uid, out Vector2 appliedImpulse, MapCoordinates mapPos, float maxRange, float minRange = 0.0f, float baseRadialDeltaV = 0.0f, float baseTangentialDeltaV = 0.0f, float? staticImpulse = null)
+        => GravPulse(uid, out appliedImpulse, mapPos, maxRange, minRange, new Matrix3x2(
+            baseRadialDeltaV, +baseTangentialDeltaV, 0.0f,
+            -baseTangentialDeltaV, baseRadialDeltaV, 0.0f
+        ), staticImpulse);
 
     #endregion GravPulse
 

Content.Shared/Singularity/Components/EventHorizonComponent.cs

@@ -81,5 +81,11 @@ public sealed partial class EventHorizonComponent : Component
     [AutoPausedField]
     public TimeSpan NextConsumeWaveTime;
 
+    /// <summary>
+    ///     Whether to inherit the momentum of consumed objects.
+    /// </summary>
+    [DataField]
+    public bool InheritMomentum;
+
     #endregion Update Timing
 }

Resources/Prototypes/Entities/Structures/Power/Generation/Singularity/singularity.yml

@@ -17,11 +17,14 @@
   - type: EventHorizon # To make the singularity consume things.
     radius: 0.5
     canBreachContainment: false
+    inheritMomentum: true
     colliderFixtureId: EventHorizonCollider
     consumerFixtureId: EventHorizonConsumer
   - type: GravityWell # To make the singularity attract things.
     baseRadialAcceleration: 10
     maxRange: 4
+    applyCounterforce: true
+    staticAttraction: 0.3
   - type: Fixtures
     fixtures:
       EventHorizonCollider:
@@ -30,7 +33,7 @@
             radius: 0.35
         hard: true
         restitution: 0.8
-        density: 99999
+        density: 2000
         mask:
         - AllMask
         layer:
@@ -52,6 +55,7 @@
   - type: RandomWalk # To make the singularity move around.
     maxSpeed: 2.5
     minSpeed: 1.875
+    accumulatorRatio: 0.7
   - type: SingularityDistortion
     falloffPower: 2.529822
     intensity: 3645

Resources/Prototypes/Entities/Structures/Power/Generation/Tesla/energyball.yml

@@ -46,7 +46,7 @@
             radius: 0.55
         hard: true
         restitution: 0.8
-        density: 99999
+        density: 2000
         mask:
         - Opaque
         layer: