Mirror: Fix shield absorbing asphyxiation damage (#140)

## Mirror of PR #25972: [Fix shield absorbing asphyxiation
damage](space-wizards/space-station-14#25972)
from <img src="https://avatars.githubusercontent.com/u/10567778?v=4"
alt="space-wizards" width="22"/>
[space-wizards](https://github.com/space-wizards)/[space-station-14](https://github.com/space-wizards/space-station-14)

###### `b0ffed1607452a2d4186228fc2343d10035611e5`

PR opened by <img
src="https://avatars.githubusercontent.com/u/32041239?v=4"
width="16"/><a href="https://github.com/nikthechampiongr">
nikthechampiongr</a> at 2024-03-10 17:36:06 UTC
PR merged by <img
src="https://avatars.githubusercontent.com/u/19864447?v=4"
width="16"/><a href="https://github.com/web-flow"> web-flow</a> at
2024-03-11 01:55:19 UTC

---

PR changed 1 files with 12 additions and 2 deletions.

The PR had the following labels:


---

<details open="true"><summary><h1>Original Body</h1></summary>

> fixes #25966
> 
> <!-- Please read these guidelines before opening your PR:
https://docs.spacestation14.io/en/getting-started/pr-guideline -->
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> 
> ## About the PR
> <!-- What did you change in this PR? -->
> The shield will now only reduce damage itself can absorb.
> 
> ## Why / Balance
> <!-- Why was it changed? Link any discussions or issues here. Please
discuss how this would affect game balance. -->
> A shield should probably not oxygenate your blood supply.
> 
> ## Technical details
> <!-- If this is a code change, summarize at high level how your new
code works. This makes it easier to review. -->
> Instead of just multiplying the damage of the user, we now create a
damagemodiferset with all the damages that the shield can take. For that
we use the shield's damageable component. This does mean that shields
that cannot take damage will no longer absorb damage.
> 
> ## Media
> <!-- 
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etc) are required to have media attached that showcase the changes.
> Small fixes/refactors are exempt.
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> 
> - [x] I have added screenshots/videos to this PR showcasing its
changes ingame, **or** this PR does not require an ingame showcase
> 
> ## Breaking changes
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class/method/field changes, prototype renames; and provide instructions
for fixing them. This will be pasted in #codebase-changes.
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> 
> **Changelog**
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> 🆑
> - add: Added fun!
> - remove: Removed fun!
> - tweak: Changed fun!
> - fix: Fixed fun!
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> 
> 🆑
> - fix: Shields will no longer absorb asphyxiation damage, or any other
damage they themselves can't take.


</details>

Co-authored-by: nikthechampiongr <32041239+nikthechampiongr@users.noreply.github.com>

Content.Shared/Blocking/BlockingSystem.User.cs

@@ -47,13 +47,23 @@ private void OnUserDamageModified(EntityUid uid, BlockingUserComponent component
             if (args.Damage.GetTotal() <= 0)
                 return;
 
+            // A shield should only block damage it can itself absorb. To determine that we need the Damageable component on it.
+            if (!TryComp<DamageableComponent>(component.BlockingItem, out var dmgComp))
+                return;
+
             var blockFraction = blocking.IsBlocking ? blocking.ActiveBlockFraction : blocking.PassiveBlockFraction;
             blockFraction = Math.Clamp(blockFraction, 0, 1);
             _damageable.TryChangeDamage(component.BlockingItem, blockFraction * args.OriginalDamage);
 
-            args.Damage *= (1 - blockFraction);
+            var modify = new DamageModifierSet();
+            foreach (var key in dmgComp.Damage.DamageDict.Keys)
+            {
+                modify.Coefficients.TryAdd(key, 1 - blockFraction);
+            }
+
+            args.Damage = DamageSpecifier.ApplyModifierSet(args.Damage, modify);
 
-            if (blocking.IsBlocking)
+            if (blocking.IsBlocking && !args.Damage.Equals(args.OriginalDamage))
             {
                 _audio.PlayPvs(blocking.BlockSound, uid);
             }