From b6004e44cff73876f2ba04f342bfe8129a7f5222 Mon Sep 17 00:00:00 2001
From: Oscar <osmithsi@sfu.ca>
Date: Fri, 30 Oct 2020 12:21:57 -0700
Subject: [PATCH] Local resources don't create if already present (#745)

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 ef1105b55d..ab33775bce 100644
--- a/crates/bevy_ecs/src/resource/resource_query.rs
+++ b/crates/bevy_ecs/src/resource/resource_query.rs
@@ -295,9 +295,13 @@ 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);
+        }
     }
 }