2 files changed, 66 insertions, 1 deletions

diff --git a/engine-ecs/src/lib.rs b/engine-ecs/src/lib.rs
index 46f4592..6656440 100644
--- a/engine-ecs/src/lib.rs
+++ b/engine-ecs/src/lib.rs
@@ -6,6 +6,7 @@ use std::fmt::Debug;
 use std::hint::cold_path;
 use std::rc::Rc;
 use std::sync::atomic::{AtomicBool, Ordering};
+use std::time::Duration;
 
 use crate::actions::Action;
 use crate::component::storage::archetype::EntityComponent as ArchetypeEntityComponent;
@@ -51,7 +52,7 @@ use crate::query::{
     MAX_TERM_CNT as QUERY_MAX_TERM_CNT,
 };
 use crate::reflection::Type as TypeReflection;
-use crate::sole::Sole;
+use crate::sole::{Single, Sole};
 use crate::system::observer::Observer;
 use crate::system::{
     Callbacks,
@@ -73,6 +74,7 @@ pub mod phase;
 pub mod query;
 pub mod sole;
 pub mod system;
+pub mod time;
 pub mod tuple;
 pub mod uid;
 pub mod util;
@@ -106,6 +108,11 @@ impl World
             error_handler: err_handler_panic,
         };
 
+        let _ = world.add_sole(time::Time {
+            delta_time: Duration::default(),
+            tick_begin: None,
+        });
+
         crate::phase::spawn_standard_phases(&mut world);
 
         crate::error::set_panic_hook();
@@ -308,6 +315,11 @@ impl World
         Some(EntityHandle::new(archetype, entity, self))
     }
 
+    pub fn get_sole<SoleT: Sole>(&self) -> Single<'_, SoleT>
+    {
+        Single::<SoleT>::new(self)
+    }
+
     pub fn event_submitter(&self) -> EventSubmitter<'_>
     {
         EventSubmitter::new(&self.data.new_events)
@@ -322,6 +334,16 @@ impl World
             return StepResult::Stop;
         }
 
+        {
+            let mut time = self.get_sole::<time::Time>();
+
+            let Ok(time) = time.get_mut() else {
+                unreachable!();
+            };
+
+            time::update(&mut *time);
+        }
+
         if self
             .is_first_tick
             .compare_exchange(false, true, Ordering::Relaxed, Ordering::Relaxed)
diff --git a/engine-ecs/src/time.rs b/engine-ecs/src/time.rs
new file mode 100644
index 0000000..3f888cb
--- /dev/null
+++ b/engine-ecs/src/time.rs
@@ -0,0 +1,43 @@
+use std::ops::Deref;
+use std::time::{Duration, Instant};
+
+use engine_ecs_macros::Sole;
+
+use crate::sole::Single;
+
+#[derive(Debug, Sole)]
+#[non_exhaustive]
+pub struct Time
+{
+    /// Time passed since the beginning of the previous tick.
+    pub delta_time: Duration,
+
+    /// Time at the beginning of the current tick.
+    pub tick_begin: Option<Instant>,
+}
+
+impl Deref for Single<'_, Time>
+{
+    type Target = Time;
+
+    fn deref(&self) -> &Self::Target
+    {
+        let Ok(time) = self.get() else {
+            // Time is always created by World::new
+            unreachable!();
+        };
+
+        time
+    }
+}
+
+pub(crate) fn update(time: &mut Time)
+{
+    let current_time = Instant::now();
+
+    let tick_begin = time.tick_begin.get_or_insert(current_time);
+
+    time.delta_time = current_time.duration_since(*tick_begin);
+
+    time.tick_begin = Some(current_time);
+}