From f98116f0f89b8aabd5ef3ce70d10dc2631fd37a6 Mon Sep 17 00:00:00 2001
From: Michael Hsu <mike.hsu@gmail.com>
Date: Fri, 13 May 2022 17:53:24 -0700
Subject: [PATCH 01/14] send time from render to app through channels

---
 crates/bevy_core/Cargo.toml            |  1 +
 crates/bevy_render/src/lib.rs          |  6 ++++++
 crates/bevy_render/src/renderer/mod.rs | 10 ++++++++++
 crates/bevy_time/src/time.rs           | 23 +++++++++++++++++++++++
 4 files changed, 40 insertions(+)

diff --git a/crates/bevy_core/Cargo.toml b/crates/bevy_core/Cargo.toml
index 7035d2fbc2235..add0c03275cb1 100644
--- a/crates/bevy_core/Cargo.toml
+++ b/crates/bevy_core/Cargo.toml
@@ -19,4 +19,5 @@ bevy_tasks = { path = "../bevy_tasks", version = "0.8.0-dev" }
 bevy_utils = { path = "../bevy_utils", version = "0.8.0-dev" }
 
 # other
+async-channel = "1.4"
 bytemuck = "1.5"
diff --git a/crates/bevy_render/src/lib.rs b/crates/bevy_render/src/lib.rs
index 0caa1a75bc29c..087f88b150b24 100644
--- a/crates/bevy_render/src/lib.rs
+++ b/crates/bevy_render/src/lib.rs
@@ -183,6 +183,12 @@ impl Plugin for RenderPlugin {
                 .insert_resource(asset_server)
                 .init_resource::<RenderGraph>();
 
+            let (sender, receiver) = bevy_core::create_time_channels();
+            app.insert_resource(receiver);
+            render_app
+                .init_resource::<bevy_core::Time>()
+                .insert_resource(sender);
+
             app.add_sub_app(RenderApp, render_app, move |app_world, render_app| {
                 #[cfg(feature = "trace")]
                 let _render_span = bevy_utils::tracing::info_span!("renderer subapp").entered();
diff --git a/crates/bevy_render/src/renderer/mod.rs b/crates/bevy_render/src/renderer/mod.rs
index 07667096ac30b..6390291ea0228 100644
--- a/crates/bevy_render/src/renderer/mod.rs
+++ b/crates/bevy_render/src/renderer/mod.rs
@@ -10,6 +10,7 @@ use crate::{
     settings::{WgpuSettings, WgpuSettingsPriority},
     view::{ExtractedWindows, ViewTarget},
 };
+use bevy_core::{Time, TimeSender};
 use bevy_ecs::prelude::*;
 use std::sync::Arc;
 use wgpu::{AdapterInfo, CommandEncoder, Instance, Queue, RequestAdapterOptions};
@@ -73,6 +74,15 @@ pub fn render_system(world: &mut World) {
             tracy.frame_mark = true
         );
     }
+
+    // update the time and send it to the app world
+    world.resource_scope(|world, mut time: Mut<Time>| {
+        let time_sender = world.resource::<TimeSender>();
+        time.update();
+        time_sender.0.try_send(time.clone()).expect(
+            "The TimeSender channel should always be empty during render. You might need to add the bevy::core::time_system to your app.",
+        );
+    });
 }
 
 /// This queue is used to enqueue tasks for the GPU to execute asynchronously.
diff --git a/crates/bevy_time/src/time.rs b/crates/bevy_time/src/time.rs
index 179eb74073b70..3e1df0aae1057 100644
--- a/crates/bevy_time/src/time.rs
+++ b/crates/bevy_time/src/time.rs
@@ -1,5 +1,18 @@
+use async_channel::{Receiver, Sender};
+use bevy_ecs::system::{Res, ResMut};
 use bevy_utils::{Duration, Instant};
 
+/// channel resource used to receive time from render world
+pub struct TimeReceiver(pub Receiver<Time>);
+/// channel resource used to send time from render world
+pub struct TimeSender(pub Sender<Time>);
+
+/// create channels used for sending time between render world and app world
+pub fn create_time_channels() -> (TimeSender, TimeReceiver) {
+    let (s, r) = async_channel::bounded::<Time>(1);
+    (TimeSender(s), TimeReceiver(r))
+}
+
 /// Tracks elapsed time since the last update and since the App has started
 #[derive(Debug, Clone)]
 pub struct Time {
@@ -142,6 +155,16 @@ impl Time {
     }
 }
 
+pub(crate) fn time_system(mut time: ResMut<Time>, time_recv: Option<Res<TimeReceiver>>) {
+    if let Some(time_recv) = time_recv {
+        if let Ok(mut new_time) = time_recv.0.try_recv() {
+            std::mem::swap(&mut *time, &mut new_time);
+        }
+    } else {
+        time.update();
+    }
+}
+
 #[cfg(test)]
 #[allow(clippy::float_cmp)]
 mod tests {

From 8f2c88c739a82fa1ae68402d7e7c1eddf410ba5e Mon Sep 17 00:00:00 2001
From: Michael Hsu <mike.hsu@gmail.com>
Date: Fri, 13 May 2022 19:33:18 -0700
Subject: [PATCH 02/14] send Instant::now() instead of full time struct

---
 crates/bevy_render/src/lib.rs          |  4 +---
 crates/bevy_render/src/renderer/mod.rs | 14 ++++++--------
 crates/bevy_time/src/time.rs           | 12 +++++++-----
 3 files changed, 14 insertions(+), 16 deletions(-)

diff --git a/crates/bevy_render/src/lib.rs b/crates/bevy_render/src/lib.rs
index 087f88b150b24..9ec31d2dbc462 100644
--- a/crates/bevy_render/src/lib.rs
+++ b/crates/bevy_render/src/lib.rs
@@ -185,9 +185,7 @@ impl Plugin for RenderPlugin {
 
             let (sender, receiver) = bevy_core::create_time_channels();
             app.insert_resource(receiver);
-            render_app
-                .init_resource::<bevy_core::Time>()
-                .insert_resource(sender);
+            render_app.insert_resource(sender);
 
             app.add_sub_app(RenderApp, render_app, move |app_world, render_app| {
                 #[cfg(feature = "trace")]
diff --git a/crates/bevy_render/src/renderer/mod.rs b/crates/bevy_render/src/renderer/mod.rs
index 6390291ea0228..cbabd7d34d40a 100644
--- a/crates/bevy_render/src/renderer/mod.rs
+++ b/crates/bevy_render/src/renderer/mod.rs
@@ -10,8 +10,9 @@ use crate::{
     settings::{WgpuSettings, WgpuSettingsPriority},
     view::{ExtractedWindows, ViewTarget},
 };
-use bevy_core::{Time, TimeSender};
+use bevy_core::TimeSender;
 use bevy_ecs::prelude::*;
+use bevy_utils::Instant;
 use std::sync::Arc;
 use wgpu::{AdapterInfo, CommandEncoder, Instance, Queue, RequestAdapterOptions};
 
@@ -76,13 +77,10 @@ pub fn render_system(world: &mut World) {
     }
 
     // update the time and send it to the app world
-    world.resource_scope(|world, mut time: Mut<Time>| {
-        let time_sender = world.resource::<TimeSender>();
-        time.update();
-        time_sender.0.try_send(time.clone()).expect(
-            "The TimeSender channel should always be empty during render. You might need to add the bevy::core::time_system to your app.",
-        );
-    });
+    let time_sender = world.resource::<TimeSender>();
+    time_sender.0.try_send(Instant::now()).expect(
+        "The TimeSender channel should always be empty during render. You might need to add the bevy::core::time_system to your app.",
+    );
 }
 
 /// This queue is used to enqueue tasks for the GPU to execute asynchronously.
diff --git a/crates/bevy_time/src/time.rs b/crates/bevy_time/src/time.rs
index 3e1df0aae1057..04a336e042531 100644
--- a/crates/bevy_time/src/time.rs
+++ b/crates/bevy_time/src/time.rs
@@ -3,13 +3,13 @@ use bevy_ecs::system::{Res, ResMut};
 use bevy_utils::{Duration, Instant};
 
 /// channel resource used to receive time from render world
-pub struct TimeReceiver(pub Receiver<Time>);
+pub struct TimeReceiver(pub Receiver<Instant>);
 /// channel resource used to send time from render world
-pub struct TimeSender(pub Sender<Time>);
+pub struct TimeSender(pub Sender<Instant>);
 
 /// create channels used for sending time between render world and app world
 pub fn create_time_channels() -> (TimeSender, TimeReceiver) {
-    let (s, r) = async_channel::bounded::<Time>(1);
+    let (s, r) = async_channel::bounded::<Instant>(1);
     (TimeSender(s), TimeReceiver(r))
 }
 
@@ -155,10 +155,12 @@ impl Time {
     }
 }
 
+/// The system used to update the time. If there is a render world the time is sent from
+/// there to this system through channels. Otherwise the time is updated in this system.
 pub(crate) fn time_system(mut time: ResMut<Time>, time_recv: Option<Res<TimeReceiver>>) {
     if let Some(time_recv) = time_recv {
-        if let Ok(mut new_time) = time_recv.0.try_recv() {
-            std::mem::swap(&mut *time, &mut new_time);
+        if let Ok(new_time) = time_recv.0.try_recv() {
+            time.update_with_instant(new_time);
         }
     } else {
         time.update();

From 2a764a7940abb9495da7bd3ba4fe45776ebb6ef8 Mon Sep 17 00:00:00 2001
From: Michael Hsu <mike.hsu@gmail.com>
Date: Thu, 19 May 2022 12:45:24 -0700
Subject: [PATCH 03/14] change bounds to 2

---
 crates/bevy_time/src/time.rs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/crates/bevy_time/src/time.rs b/crates/bevy_time/src/time.rs
index 04a336e042531..752593ac4f019 100644
--- a/crates/bevy_time/src/time.rs
+++ b/crates/bevy_time/src/time.rs
@@ -9,7 +9,9 @@ pub struct TimeSender(pub Sender<Instant>);
 
 /// create channels used for sending time between render world and app world
 pub fn create_time_channels() -> (TimeSender, TimeReceiver) {
-    let (s, r) = async_channel::bounded::<Instant>(1);
+    // bound the channel to 2 since when pipelined the render phase can finish before
+    // the time system runs.
+    let (s, r) = async_channel::bounded::<Instant>(2);
     (TimeSender(s), TimeReceiver(r))
 }
 

From 8291f6b2aed7896bf950d4a3eb90a80b1d939a40 Mon Sep 17 00:00:00 2001
From: Michael Hsu <mike.hsu@gmail.com>
Date: Thu, 19 May 2022 13:07:17 -0700
Subject: [PATCH 04/14] add error

---
 crates/bevy_time/src/time.rs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/crates/bevy_time/src/time.rs b/crates/bevy_time/src/time.rs
index 752593ac4f019..c730d355af0fb 100644
--- a/crates/bevy_time/src/time.rs
+++ b/crates/bevy_time/src/time.rs
@@ -1,6 +1,6 @@
 use async_channel::{Receiver, Sender};
 use bevy_ecs::system::{Res, ResMut};
-use bevy_utils::{Duration, Instant};
+use bevy_utils::{tracing::warn, Duration, Instant};
 
 /// channel resource used to receive time from render world
 pub struct TimeReceiver(pub Receiver<Instant>);
@@ -163,6 +163,8 @@ pub(crate) fn time_system(mut time: ResMut<Time>, time_recv: Option<Res<TimeRece
     if let Some(time_recv) = time_recv {
         if let Ok(new_time) = time_recv.0.try_recv() {
             time.update_with_instant(new_time);
+        } else {
+            warn!("time_system did not receive time from render world! Calculations depending on the time may be incorrect.");
         }
     } else {
         time.update();

From 14a8800387cec096adc9dffb1c5e13220d6c4f42 Mon Sep 17 00:00:00 2001
From: Michael Hsu <mike.hsu@gmail.com>
Date: Thu, 19 May 2022 13:09:11 -0700
Subject: [PATCH 05/14] add warning if time is not updated

---
 crates/bevy_time/src/time.rs | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/crates/bevy_time/src/time.rs b/crates/bevy_time/src/time.rs
index c730d355af0fb..de9c5bd458d87 100644
--- a/crates/bevy_time/src/time.rs
+++ b/crates/bevy_time/src/time.rs
@@ -1,5 +1,5 @@
 use async_channel::{Receiver, Sender};
-use bevy_ecs::system::{Res, ResMut};
+use bevy_ecs::system::{Local, Res, ResMut};
 use bevy_utils::{tracing::warn, Duration, Instant};
 
 /// channel resource used to receive time from render world
@@ -159,11 +159,16 @@ impl Time {
 
 /// The system used to update the time. If there is a render world the time is sent from
 /// there to this system through channels. Otherwise the time is updated in this system.
-pub(crate) fn time_system(mut time: ResMut<Time>, time_recv: Option<Res<TimeReceiver>>) {
+pub(crate) fn time_system(
+    mut time: ResMut<Time>,
+    time_recv: Option<Res<TimeReceiver>>,
+    mut has_received_time: Local<bool>,
+) {
     if let Some(time_recv) = time_recv {
         if let Ok(new_time) = time_recv.0.try_recv() {
             time.update_with_instant(new_time);
-        } else {
+            *has_received_time = true;
+        } else if *has_received_time {
             warn!("time_system did not receive time from render world! Calculations depending on the time may be incorrect.");
         }
     } else {

From e1e2fcc929b3da1a5d494598eb590b7dedebfe98 Mon Sep 17 00:00:00 2001
From: Michael Hsu <mike.hsu@gmail.com>
Date: Thu, 19 May 2022 15:15:29 -0700
Subject: [PATCH 06/14] switch to crossbeam

---
 crates/bevy_core/Cargo.toml  | 2 +-
 crates/bevy_time/src/time.rs | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/crates/bevy_core/Cargo.toml b/crates/bevy_core/Cargo.toml
index add0c03275cb1..a5eef9febdeb7 100644
--- a/crates/bevy_core/Cargo.toml
+++ b/crates/bevy_core/Cargo.toml
@@ -19,5 +19,5 @@ bevy_tasks = { path = "../bevy_tasks", version = "0.8.0-dev" }
 bevy_utils = { path = "../bevy_utils", version = "0.8.0-dev" }
 
 # other
-async-channel = "1.4"
+crossbeam-channel = "0.5.0"
 bytemuck = "1.5"
diff --git a/crates/bevy_time/src/time.rs b/crates/bevy_time/src/time.rs
index de9c5bd458d87..a36f093800388 100644
--- a/crates/bevy_time/src/time.rs
+++ b/crates/bevy_time/src/time.rs
@@ -1,6 +1,6 @@
-use async_channel::{Receiver, Sender};
 use bevy_ecs::system::{Local, Res, ResMut};
 use bevy_utils::{tracing::warn, Duration, Instant};
+use crossbeam_channel::{Receiver, Sender};
 
 /// channel resource used to receive time from render world
 pub struct TimeReceiver(pub Receiver<Instant>);
@@ -11,7 +11,7 @@ pub struct TimeSender(pub Sender<Instant>);
 pub fn create_time_channels() -> (TimeSender, TimeReceiver) {
     // bound the channel to 2 since when pipelined the render phase can finish before
     // the time system runs.
-    let (s, r) = async_channel::bounded::<Instant>(2);
+    let (s, r) = crossbeam_channel::bounded::<Instant>(2);
     (TimeSender(s), TimeReceiver(r))
 }
 

From 183e016ce2d02bc1dfa4b1915b9d2726eafacd0c Mon Sep 17 00:00:00 2001
From: Michael Hsu <mike.hsu@gmail.com>
Date: Thu, 19 May 2022 15:18:56 -0700
Subject: [PATCH 07/14] reorder types closer to time_system where they're used

---
 crates/bevy_time/src/time.rs | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/crates/bevy_time/src/time.rs b/crates/bevy_time/src/time.rs
index a36f093800388..11baedbb5f13d 100644
--- a/crates/bevy_time/src/time.rs
+++ b/crates/bevy_time/src/time.rs
@@ -2,19 +2,6 @@ use bevy_ecs::system::{Local, Res, ResMut};
 use bevy_utils::{tracing::warn, Duration, Instant};
 use crossbeam_channel::{Receiver, Sender};
 
-/// channel resource used to receive time from render world
-pub struct TimeReceiver(pub Receiver<Instant>);
-/// channel resource used to send time from render world
-pub struct TimeSender(pub Sender<Instant>);
-
-/// create channels used for sending time between render world and app world
-pub fn create_time_channels() -> (TimeSender, TimeReceiver) {
-    // bound the channel to 2 since when pipelined the render phase can finish before
-    // the time system runs.
-    let (s, r) = crossbeam_channel::bounded::<Instant>(2);
-    (TimeSender(s), TimeReceiver(r))
-}
-
 /// Tracks elapsed time since the last update and since the App has started
 #[derive(Debug, Clone)]
 pub struct Time {
@@ -157,6 +144,19 @@ impl Time {
     }
 }
 
+/// channel resource used to receive time from render world
+pub struct TimeReceiver(pub Receiver<Instant>);
+/// channel resource used to send time from render world
+pub struct TimeSender(pub Sender<Instant>);
+
+/// create channels used for sending time between render world and app world
+pub fn create_time_channels() -> (TimeSender, TimeReceiver) {
+    // bound the channel to 2 since when pipelined the render phase can finish before
+    // the time system runs.
+    let (s, r) = crossbeam_channel::bounded::<Instant>(2);
+    (TimeSender(s), TimeReceiver(r))
+}
+
 /// The system used to update the time. If there is a render world the time is sent from
 /// there to this system through channels. Otherwise the time is updated in this system.
 pub(crate) fn time_system(

From e8daf696f84e8aa01ede5c5d4701e1ee958687ef Mon Sep 17 00:00:00 2001
From: Mike Hsu <mike.hsu@gmail.com>
Date: Sun, 22 May 2022 14:09:54 -0700
Subject: [PATCH 08/14] add todo

---
 crates/bevy_time/src/time.rs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/crates/bevy_time/src/time.rs b/crates/bevy_time/src/time.rs
index 11baedbb5f13d..26b481e384121 100644
--- a/crates/bevy_time/src/time.rs
+++ b/crates/bevy_time/src/time.rs
@@ -165,6 +165,8 @@ pub(crate) fn time_system(
     mut has_received_time: Local<bool>,
 ) {
     if let Some(time_recv) = time_recv {
+        // TODO: delay checking channel on start by 2 frames when pipelined rendering
+        // is enabled. This is to make sure we always read the N-2 frame's time.
         if let Ok(new_time) = time_recv.0.try_recv() {
             time.update_with_instant(new_time);
             *has_received_time = true;

From 0edf044032a0b4e152cf12a1c64cf806cc1d7b0d Mon Sep 17 00:00:00 2001
From: Michael Hsu <mike.hsu@gmail.com>
Date: Thu, 26 May 2022 10:52:33 -0700
Subject: [PATCH 09/14] fix some rebase issues

---
 crates/bevy_core/Cargo.toml            |  1 -
 crates/bevy_render/Cargo.toml          |  1 +
 crates/bevy_render/src/lib.rs          |  2 +-
 crates/bevy_render/src/renderer/mod.rs |  2 +-
 crates/bevy_time/Cargo.toml            |  3 ++
 crates/bevy_time/src/lib.rs            | 38 ++++++++++++++++++++++++--
 crates/bevy_time/src/time.rs           | 38 +-------------------------
 7 files changed, 43 insertions(+), 42 deletions(-)

diff --git a/crates/bevy_core/Cargo.toml b/crates/bevy_core/Cargo.toml
index a5eef9febdeb7..7035d2fbc2235 100644
--- a/crates/bevy_core/Cargo.toml
+++ b/crates/bevy_core/Cargo.toml
@@ -19,5 +19,4 @@ bevy_tasks = { path = "../bevy_tasks", version = "0.8.0-dev" }
 bevy_utils = { path = "../bevy_utils", version = "0.8.0-dev" }
 
 # other
-crossbeam-channel = "0.5.0"
 bytemuck = "1.5"
diff --git a/crates/bevy_render/Cargo.toml b/crates/bevy_render/Cargo.toml
index 879dbbbf9af9d..56c047aa3b10e 100644
--- a/crates/bevy_render/Cargo.toml
+++ b/crates/bevy_render/Cargo.toml
@@ -38,6 +38,7 @@ bevy_math = { path = "../bevy_math", version = "0.8.0-dev" }
 bevy_mikktspace = { path = "../bevy_mikktspace", version = "0.8.0-dev" }
 bevy_reflect = { path = "../bevy_reflect", version = "0.8.0-dev", features = ["bevy"] }
 bevy_render_macros = { path = "macros", version = "0.8.0-dev" }
+bevy_time = { path = "../bevy_time", version = "0.8.0-dev" }
 bevy_transform = { path = "../bevy_transform", version = "0.8.0-dev" }
 bevy_window = { path = "../bevy_window", version = "0.8.0-dev" }
 bevy_utils = { path = "../bevy_utils", version = "0.8.0-dev" }
diff --git a/crates/bevy_render/src/lib.rs b/crates/bevy_render/src/lib.rs
index 9ec31d2dbc462..418607bb62a2c 100644
--- a/crates/bevy_render/src/lib.rs
+++ b/crates/bevy_render/src/lib.rs
@@ -183,7 +183,7 @@ impl Plugin for RenderPlugin {
                 .insert_resource(asset_server)
                 .init_resource::<RenderGraph>();
 
-            let (sender, receiver) = bevy_core::create_time_channels();
+            let (sender, receiver) = bevy_time::create_time_channels();
             app.insert_resource(receiver);
             render_app.insert_resource(sender);
 
diff --git a/crates/bevy_render/src/renderer/mod.rs b/crates/bevy_render/src/renderer/mod.rs
index cbabd7d34d40a..115893d76d673 100644
--- a/crates/bevy_render/src/renderer/mod.rs
+++ b/crates/bevy_render/src/renderer/mod.rs
@@ -10,8 +10,8 @@ use crate::{
     settings::{WgpuSettings, WgpuSettingsPriority},
     view::{ExtractedWindows, ViewTarget},
 };
-use bevy_core::TimeSender;
 use bevy_ecs::prelude::*;
+use bevy_time::TimeSender;
 use bevy_utils::Instant;
 use std::sync::Arc;
 use wgpu::{AdapterInfo, CommandEncoder, Instance, Queue, RequestAdapterOptions};
diff --git a/crates/bevy_time/Cargo.toml b/crates/bevy_time/Cargo.toml
index b1b2c03ff8bf7..897706ab57415 100644
--- a/crates/bevy_time/Cargo.toml
+++ b/crates/bevy_time/Cargo.toml
@@ -15,3 +15,6 @@ bevy_app = { path = "../bevy_app", version = "0.8.0-dev" }
 bevy_ecs = { path = "../bevy_ecs", version = "0.8.0-dev", features = ["bevy_reflect"] }
 bevy_reflect = { path = "../bevy_reflect", version = "0.8.0-dev", features = ["bevy"] }
 bevy_utils = { path = "../bevy_utils", version = "0.8.0-dev" }
+
+# other
+crossbeam-channel = "0.5.0"
\ No newline at end of file
diff --git a/crates/bevy_time/src/lib.rs b/crates/bevy_time/src/lib.rs
index dc1f48552031c..32ab248d05ae0 100644
--- a/crates/bevy_time/src/lib.rs
+++ b/crates/bevy_time/src/lib.rs
@@ -9,6 +9,10 @@ pub use stopwatch::*;
 pub use time::*;
 pub use timer::*;
 
+use bevy_ecs::system::{Local, Res, ResMut};
+use bevy_utils::{tracing::warn, Instant};
+use crossbeam_channel::{Receiver, Sender};
+
 pub mod prelude {
     //! The Bevy Time Prelude.
     #[doc(hidden)]
@@ -41,6 +45,36 @@ impl Plugin for TimePlugin {
     }
 }
 
-fn time_system(mut time: ResMut<Time>) {
-    time.update();
+/// channel resource used to receive time from render world
+pub struct TimeReceiver(pub Receiver<Instant>);
+/// channel resource used to send time from render world
+pub struct TimeSender(pub Sender<Instant>);
+
+/// create channels used for sending time between render world and app world
+pub fn create_time_channels() -> (TimeSender, TimeReceiver) {
+    // bound the channel to 2 since when pipelined the render phase can finish before
+    // the time system runs.
+    let (s, r) = crossbeam_channel::bounded::<Instant>(2);
+    (TimeSender(s), TimeReceiver(r))
+}
+
+/// The system used to update the time. If there is a render world the time is sent from
+/// there to this system through channels. Otherwise the time is updated in this system.]
+fn time_system(
+    mut time: ResMut<Time>,
+    time_recv: Option<Res<TimeReceiver>>,
+    mut has_received_time: Local<bool>,
+) {
+    if let Some(time_recv) = time_recv {
+        // TODO: delay checking channel on start by 2 frames when pipelined rendering
+        // is enabled. This is to make sure we always read the N-2 frame's time.
+        if let Ok(new_time) = time_recv.0.try_recv() {
+            time.update_with_instant(new_time);
+            *has_received_time = true;
+        } else if *has_received_time {
+            warn!("time_system did not receive time from render world! Calculations depending on the time may be incorrect.");
+        }
+    } else {
+        time.update();
+    }
 }
diff --git a/crates/bevy_time/src/time.rs b/crates/bevy_time/src/time.rs
index 26b481e384121..179eb74073b70 100644
--- a/crates/bevy_time/src/time.rs
+++ b/crates/bevy_time/src/time.rs
@@ -1,6 +1,4 @@
-use bevy_ecs::system::{Local, Res, ResMut};
-use bevy_utils::{tracing::warn, Duration, Instant};
-use crossbeam_channel::{Receiver, Sender};
+use bevy_utils::{Duration, Instant};
 
 /// Tracks elapsed time since the last update and since the App has started
 #[derive(Debug, Clone)]
@@ -144,40 +142,6 @@ impl Time {
     }
 }
 
-/// channel resource used to receive time from render world
-pub struct TimeReceiver(pub Receiver<Instant>);
-/// channel resource used to send time from render world
-pub struct TimeSender(pub Sender<Instant>);
-
-/// create channels used for sending time between render world and app world
-pub fn create_time_channels() -> (TimeSender, TimeReceiver) {
-    // bound the channel to 2 since when pipelined the render phase can finish before
-    // the time system runs.
-    let (s, r) = crossbeam_channel::bounded::<Instant>(2);
-    (TimeSender(s), TimeReceiver(r))
-}
-
-/// The system used to update the time. If there is a render world the time is sent from
-/// there to this system through channels. Otherwise the time is updated in this system.
-pub(crate) fn time_system(
-    mut time: ResMut<Time>,
-    time_recv: Option<Res<TimeReceiver>>,
-    mut has_received_time: Local<bool>,
-) {
-    if let Some(time_recv) = time_recv {
-        // TODO: delay checking channel on start by 2 frames when pipelined rendering
-        // is enabled. This is to make sure we always read the N-2 frame's time.
-        if let Ok(new_time) = time_recv.0.try_recv() {
-            time.update_with_instant(new_time);
-            *has_received_time = true;
-        } else if *has_received_time {
-            warn!("time_system did not receive time from render world! Calculations depending on the time may be incorrect.");
-        }
-    } else {
-        time.update();
-    }
-}
-
 #[cfg(test)]
 #[allow(clippy::float_cmp)]
 mod tests {

From f55c400798f5e58dfc94ea09be65a6cb1aeb3fce Mon Sep 17 00:00:00 2001
From: Mike <mike.hsu@gmail.com>
Date: Tue, 7 Jun 2022 21:03:27 -0700
Subject: [PATCH 10/14] link to Time in docs

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
---
 crates/bevy_time/src/lib.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crates/bevy_time/src/lib.rs b/crates/bevy_time/src/lib.rs
index 32ab248d05ae0..27eb191d94dc0 100644
--- a/crates/bevy_time/src/lib.rs
+++ b/crates/bevy_time/src/lib.rs
@@ -58,7 +58,7 @@ pub fn create_time_channels() -> (TimeSender, TimeReceiver) {
     (TimeSender(s), TimeReceiver(r))
 }
 
-/// The system used to update the time. If there is a render world the time is sent from
+/// The system used to update the [`Time`] used by app logic. If there is a render world the time is sent from
 /// there to this system through channels. Otherwise the time is updated in this system.]
 fn time_system(
     mut time: ResMut<Time>,

From 565a9a17847ab4e82ca66d1e69535dce752d570b Mon Sep 17 00:00:00 2001
From: Mike Hsu <mike.hsu@gmail.com>
Date: Tue, 7 Jun 2022 21:10:55 -0700
Subject: [PATCH 11/14] fix some doc nits

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
---
 crates/bevy_time/src/lib.rs | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/crates/bevy_time/src/lib.rs b/crates/bevy_time/src/lib.rs
index 27eb191d94dc0..2572216152079 100644
--- a/crates/bevy_time/src/lib.rs
+++ b/crates/bevy_time/src/lib.rs
@@ -45,12 +45,12 @@ impl Plugin for TimePlugin {
     }
 }
 
-/// channel resource used to receive time from render world
+/// Channel resource used to receive time from render world
 pub struct TimeReceiver(pub Receiver<Instant>);
-/// channel resource used to send time from render world
+/// Channel resource used to send time from render world
 pub struct TimeSender(pub Sender<Instant>);
 
-/// create channels used for sending time between render world and app world
+/// Creates channels used for sending time between render world and app world
 pub fn create_time_channels() -> (TimeSender, TimeReceiver) {
     // bound the channel to 2 since when pipelined the render phase can finish before
     // the time system runs.
@@ -59,7 +59,7 @@ pub fn create_time_channels() -> (TimeSender, TimeReceiver) {
 }
 
 /// The system used to update the [`Time`] used by app logic. If there is a render world the time is sent from
-/// there to this system through channels. Otherwise the time is updated in this system.]
+/// there to this system through channels. Otherwise the time is updated in this system.
 fn time_system(
     mut time: ResMut<Time>,
     time_recv: Option<Res<TimeReceiver>>,

From 205c0af252b55eaeab33201cda0116959c87ac85 Mon Sep 17 00:00:00 2001
From: Mike <mike.hsu@gmail.com>
Date: Wed, 6 Jul 2022 12:43:53 -0700
Subject: [PATCH 12/14] shorter todo

Co-authored-by: Robert Swain <robert.swain@gmail.com>
---
 crates/bevy_time/src/lib.rs | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/crates/bevy_time/src/lib.rs b/crates/bevy_time/src/lib.rs
index 2572216152079..c9719e38a197b 100644
--- a/crates/bevy_time/src/lib.rs
+++ b/crates/bevy_time/src/lib.rs
@@ -66,8 +66,7 @@ fn time_system(
     mut has_received_time: Local<bool>,
 ) {
     if let Some(time_recv) = time_recv {
-        // TODO: delay checking channel on start by 2 frames when pipelined rendering
-        // is enabled. This is to make sure we always read the N-2 frame's time.
+        // TODO: Figure out how to handle this when using pipelined rendering.
         if let Ok(new_time) = time_recv.0.try_recv() {
             time.update_with_instant(new_time);
             *has_received_time = true;

From 8fb4c948899c6b688ceeeb53d35a119cf9d877ac Mon Sep 17 00:00:00 2001
From: Mike <mike.hsu@gmail.com>
Date: Wed, 6 Jul 2022 12:44:11 -0700
Subject: [PATCH 13/14] grammar

Co-authored-by: Robert Swain <robert.swain@gmail.com>
---
 crates/bevy_time/src/lib.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crates/bevy_time/src/lib.rs b/crates/bevy_time/src/lib.rs
index c9719e38a197b..5982305159766 100644
--- a/crates/bevy_time/src/lib.rs
+++ b/crates/bevy_time/src/lib.rs
@@ -71,7 +71,7 @@ fn time_system(
             time.update_with_instant(new_time);
             *has_received_time = true;
         } else if *has_received_time {
-            warn!("time_system did not receive time from render world! Calculations depending on the time may be incorrect.");
+            warn!("time_system did not receive the time from the render world! Calculations depending on the time may be incorrect.");
         }
     } else {
         time.update();

From 70f66cee66b2c18998179464c460300603642938 Mon Sep 17 00:00:00 2001
From: Mike <mike.hsu@gmail.com>
Date: Wed, 6 Jul 2022 12:45:27 -0700
Subject: [PATCH 14/14] add newline

---
 crates/bevy_time/Cargo.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crates/bevy_time/Cargo.toml b/crates/bevy_time/Cargo.toml
index 897706ab57415..46f570fffc591 100644
--- a/crates/bevy_time/Cargo.toml
+++ b/crates/bevy_time/Cargo.toml
@@ -17,4 +17,4 @@ bevy_reflect = { path = "../bevy_reflect", version = "0.8.0-dev", features = ["b
 bevy_utils = { path = "../bevy_utils", version = "0.8.0-dev" }
 
 # other
-crossbeam-channel = "0.5.0"
\ No newline at end of file
+crossbeam-channel = "0.5.0"