From bc5cd939572b5ec64b8c5ac7a144b4bcd9a91a6d Mon Sep 17 00:00:00 2001
From: Oscar <osmithsi@sfu.ca>
Date: Wed, 28 Oct 2020 17:15:44 -0700
Subject: [PATCH] Local resources don't create if already present

Local<T> will no longer insert the inner resource if it already exists.
---
 crates/bevy_ecs/src/resource/resource_query.rs | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/crates/bevy_ecs/src/resource/resource_query.rs b/crates/bevy_ecs/src/resource/resource_query.rs
index 267f45a8a09e8..92742343b47c6 100644
--- a/crates/bevy_ecs/src/resource/resource_query.rs
+++ b/crates/bevy_ecs/src/resource/resource_query.rs
@@ -297,9 +297,13 @@ impl<'a, T: Resource + FromResources> ResourceQuery for Local<'a, T> {
     type Fetch = FetchResourceLocalMut<T>;
 
     fn initialize(resources: &mut Resources, id: Option<SystemId>) {
-        let value = T::from_resources(resources);
         let id = id.expect("Local<T> resources can only be used by systems");
-        resources.insert_local(id, value);
+
+        // Only add the local resource if it doesn't already exist for this system
+        if resources.get_local::<T>(id).is_none() {
+            let value = T::from_resources(resources);
+            resources.insert_local(id, value);
+        }
     }
 }