From d341f456de24242950c3dea98259515affb77348 Mon Sep 17 00:00:00 2001
From: Salex08 <33989683+Salex08@users.noreply.github.com>
Date: Sat, 5 Nov 2022 04:08:32 +0100
Subject: [PATCH] Shot Projectile cause impulses in Space like they were
 supposed to (#12264)

---
 .../Weapons/Ranged/Systems/SharedGunSystem.cs | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/Content.Shared/Weapons/Ranged/Systems/SharedGunSystem.cs b/Content.Shared/Weapons/Ranged/Systems/SharedGunSystem.cs
index f24c1716e8..569d66496a 100644
--- a/Content.Shared/Weapons/Ranged/Systems/SharedGunSystem.cs
+++ b/Content.Shared/Weapons/Ranged/Systems/SharedGunSystem.cs
@@ -5,6 +5,7 @@ using Content.Shared.CombatMode;
 using Content.Shared.Containers.ItemSlots;
 using Content.Shared.Damage;
 using Content.Shared.Examine;
+using Content.Shared.Gravity;
 using Content.Shared.Hands.Components;
 using Content.Shared.Interaction.Events;
 using Content.Shared.Popups;
@@ -20,6 +21,7 @@ using Robust.Shared.GameStates;
 using Robust.Shared.Map;
 using Robust.Shared.Network;
 using Robust.Shared.Physics.Systems;
+using Robust.Shared.Physics.Components;
 using Robust.Shared.Player;
 using Robust.Shared.Prototypes;
 using Robust.Shared.Random;
@@ -38,6 +40,7 @@ public abstract partial class SharedGunSystem : EntitySystem
     [Dependency] protected readonly IRobustRandom Random = default!;
     [Dependency] protected readonly ISharedAdminLogManager Logs = default!;
     [Dependency] protected readonly DamageableSystem Damageable = default!;
+    [Dependency] private readonly SharedGravitySystem Gravity = default!;
     [Dependency] private   readonly ItemSlotsSystem _slots = default!;
     [Dependency] protected readonly SharedActionsSystem Actions = default!;
     [Dependency] protected readonly SharedAppearanceSystem Appearance = default!;
@@ -285,6 +288,12 @@ public abstract partial class SharedGunSystem : EntitySystem
 
         // Shoot confirmed - sounds also played here in case it's invalid (e.g. cartridge already spent).
         Shoot(gun, ev.Ammo, fromCoordinates, toCoordinates.Value, user);
+        // Projectiles cause impulses especially important in non gravity environments
+        if (TryComp<PhysicsComponent>(user, out var userPhysics))
+        {
+            if (Gravity.IsWeightless(user, userPhysics))
+                CauseImpulse(fromCoordinates, toCoordinates.Value, userPhysics);
+        }
         Dirty(gun);
     }
 
@@ -366,6 +375,16 @@ public abstract partial class SharedGunSystem : EntitySystem
         CreateEffect(gun, ev, user);
     }
 
+    public void CauseImpulse(EntityCoordinates fromCoordinates, EntityCoordinates toCoordinates, PhysicsComponent userPhysics)
+    {
+        var fromMap = fromCoordinates.ToMapPos(EntityManager);
+        var toMap = toCoordinates.ToMapPos(EntityManager);
+        var shotDirection = (toMap - fromMap).Normalized;
+
+        const float impulseStrength = 85.0f; //The bullet impulse strength, TODO: In the future we might want to make it more projectile dependent
+        var impulseVector =  shotDirection * impulseStrength;
+        Physics.ApplyLinearImpulse(userPhysics, -impulseVector);
+    }
     protected abstract void CreateEffect(EntityUid uid, MuzzleFlashEvent message, EntityUid? user = null);
 
     [Serializable, NetSerializable]