From 46713824193b0254b5b6d4e6c517e4120b513c15 Mon Sep 17 00:00:00 2001
From: Victor Shen <71985089+Vexerot@users.noreply.github.com>
Date: Mon, 28 Apr 2025 17:24:12 -0700
Subject: [PATCH] Remove Contact Slowdown when Weightless or in the Air
 (#33299)

* removed contact slowdowns from entities that are weightless or in the air

* fixed kudzu not applying contact slowdown to airbone entities

* revert kudzu fix

* reimplemented kudzu fix with bool datafield

* update variable serialization format

Co-authored-by: Ed <96445749+TheShuEd@users.noreply.github.com>

* empty commit

* cleaned up and added documentation

* cached airborne check

* rerun tests

* minor review

---------

Co-authored-by: Ed <96445749+TheShuEd@users.noreply.github.com>
Co-authored-by: Milon <milonpl.git@proton.me>
---
 .../SpeedModifierContactsComponent.cs         | 30 ++++++++++++++-----
 .../Systems/SpeedModifierContactsSystem.cs    |  9 ++++++
 .../Entities/Objects/Misc/kudzu.yml           |  2 ++
 3 files changed, 33 insertions(+), 8 deletions(-)

diff --git a/Content.Shared/Movement/Components/SpeedModifierContactsComponent.cs b/Content.Shared/Movement/Components/SpeedModifierContactsComponent.cs
index 73bb0690fd..f288363a2d 100644
--- a/Content.Shared/Movement/Components/SpeedModifierContactsComponent.cs
+++ b/Content.Shared/Movement/Components/SpeedModifierContactsComponent.cs
@@ -4,19 +4,33 @@ using Robust.Shared.GameStates;
 
 namespace Content.Shared.Movement.Components;
 
-[NetworkedComponent, RegisterComponent]
-[AutoGenerateComponentState]
-[Access(typeof(SpeedModifierContactsSystem))]
+/// <summary>
+/// Component that modifies the movement speed of other entities that come into contact with the entity this component is added to.
+/// </summary>
+[RegisterComponent, NetworkedComponent, AutoGenerateComponentState, Access(typeof(SpeedModifierContactsSystem))]
 public sealed partial class SpeedModifierContactsComponent : Component
 {
-    [DataField("walkSpeedModifier"), ViewVariables(VVAccess.ReadWrite)]
-    [AutoNetworkedField]
+    /// <summary>
+    /// The modifier applied to the walk speed of entities that come into contact with the entity this component is added to.
+    /// </summary>
+    [DataField, AutoNetworkedField]
     public float WalkSpeedModifier = 1.0f;
 
-    [AutoNetworkedField]
-    [DataField("sprintSpeedModifier"), ViewVariables(VVAccess.ReadWrite)]
+    /// <summary>
+    /// The modifier applied to the sprint speed of entities that come into contact with the entity this component is added to.
+    /// </summary>
+    [DataField, AutoNetworkedField]
     public float SprintSpeedModifier = 1.0f;
 
-    [DataField("ignoreWhitelist")]
+    /// <summary>
+    /// Indicates whether this component affects the movement speed of airborne entities that come into contact with the entity this component is added to.
+    /// </summary>
+    [DataField, AutoNetworkedField]
+    public bool AffectAirborne;
+
+    /// <summary>
+    /// A whitelist of entities that should be ignored by this component's speed modifiers.
+    /// </summary>
+    [DataField]
     public EntityWhitelist? IgnoreWhitelist;
 }
diff --git a/Content.Shared/Movement/Systems/SpeedModifierContactsSystem.cs b/Content.Shared/Movement/Systems/SpeedModifierContactsSystem.cs
index 089fbbf924..e53a4351d1 100644
--- a/Content.Shared/Movement/Systems/SpeedModifierContactsSystem.cs
+++ b/Content.Shared/Movement/Systems/SpeedModifierContactsSystem.cs
@@ -1,6 +1,7 @@
 using Content.Shared.Inventory;
 using Content.Shared.Movement.Components;
 using Content.Shared.Movement.Events;
+using Content.Shared.Gravity;
 using Content.Shared.Slippery;
 using Content.Shared.Whitelist;
 using Robust.Shared.Physics.Components;
@@ -12,6 +13,7 @@ namespace Content.Shared.Movement.Systems;
 public sealed class SpeedModifierContactsSystem : EntitySystem
 {
     [Dependency] private readonly SharedPhysicsSystem _physics = default!;
+    [Dependency] private readonly SharedGravitySystem _gravity = default!;
     [Dependency] private readonly MovementSpeedModifierSystem _speedModifierSystem = default!;
     [Dependency] private readonly EntityWhitelistSystem _whitelistSystem = default!;
 
@@ -84,6 +86,9 @@ public sealed class SpeedModifierContactsSystem : EntitySystem
         var walkSpeed = 0.0f;
         var sprintSpeed = 0.0f;
 
+        // Cache the result of the airborne check, as it's expensive and independent of contacting entities, hence need only be done once.
+        var isAirborne = physicsComponent.BodyStatus == BodyStatus.InAir || _gravity.IsWeightless(uid, physicsComponent);
+
         bool remove = true;
         var entries = 0;
         foreach (var ent in _physics.GetContactingEntities(uid, physicsComponent))
@@ -95,6 +100,10 @@ public sealed class SpeedModifierContactsSystem : EntitySystem
                 if (_whitelistSystem.IsWhitelistPass(slowContactsComponent.IgnoreWhitelist, uid))
                     continue;
 
+                // Entities that are airborne should not be affected by contact slowdowns that are specified to not affect airborne entities.
+                if (isAirborne && !slowContactsComponent.AffectAirborne)
+                    continue;
+
                 walkSpeed += slowContactsComponent.WalkSpeedModifier;
                 sprintSpeed += slowContactsComponent.SprintSpeedModifier;
                 speedModified = true;
diff --git a/Resources/Prototypes/Entities/Objects/Misc/kudzu.yml b/Resources/Prototypes/Entities/Objects/Misc/kudzu.yml
index c688c7cadc..e35e915b09 100644
--- a/Resources/Prototypes/Entities/Objects/Misc/kudzu.yml
+++ b/Resources/Prototypes/Entities/Objects/Misc/kudzu.yml
@@ -15,6 +15,8 @@
     - type: ActiveEdgeSpreader
     - type: EdgeSpreader
       id: Kudzu
+    - type: SpeedModifierContacts
+      affectAirborne: true
 
 - type: entity
   id: Kudzu
-- 
2.51.2