From 197080e5fdfcfc7d1143716fe7082a665d44a34c Mon Sep 17 00:00:00 2001
From: Nolan Darilek <nolan@thewordnerd.info>
Date: Wed, 16 Mar 2022 10:50:43 -0500
Subject: [PATCH] Trim down on unnecessary visibility updates.

---
 src/visibility.rs | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/src/visibility.rs b/src/visibility.rs
index 8bf4f21..0fb4d66 100644
--- a/src/visibility.rs
+++ b/src/visibility.rs
@@ -22,6 +22,10 @@ use crate::{
 #[reflect(Component)]
 pub struct DontLogWhenVisible;
 
+#[derive(Component, Clone, Debug, Default, Deref, DerefMut, Reflect)]
+#[reflect(Component)]
+struct LastCoordinates((i32, i32));
+
 #[derive(Component, Clone, Debug, Default, Deref, DerefMut, Reflect)]
 #[reflect(Component)]
 pub struct RevealedTiles(pub Vec<bool>);
@@ -242,8 +246,16 @@ where
 }
 
 fn update_viewshed<D: 'static + Clone + Default + Send + Sync>(
+    mut commands: Commands,
     config: Res<RapierConfiguration>,
-    positions: Query<(Entity, &RigidBodyPositionComponent), Changed<RigidBodyPositionComponent>>,
+    positions: Query<
+        (
+            Entity,
+            &RigidBodyPositionComponent,
+            Option<&LastCoordinates>,
+        ),
+        Changed<RigidBodyPositionComponent>,
+    >,
     visible: Query<&Visible>,
     mut viewers: Query<(Entity, &mut Viewshed, &mut VisibleEntities, &Coordinates)>,
     map: Query<&Map<D>>,
@@ -255,7 +267,7 @@ fn update_viewshed<D: 'static + Clone + Default + Send + Sync>(
         return;
     }
     let mut to_update = HashSet::new();
-    for (entity, position) in positions.iter() {
+    for (entity, position, last_coordinates) in positions.iter() {
         if to_update.contains(&entity) {
             continue;
         }
@@ -263,8 +275,15 @@ fn update_viewshed<D: 'static + Clone + Default + Send + Sync>(
             position.position.translation.x,
             position.position.translation.y,
         );
+        commands
+            .entity(entity)
+            .insert(LastCoordinates(coordinates.i32()));
         if viewers.get_mut(entity).is_ok() {
-            to_update.insert(entity);
+            if let Some(last_coordinates) = last_coordinates {
+                if **last_coordinates != coordinates.i32() {
+                    to_update.insert(entity);
+                }
+            }
         }
         if visible.get(entity).is_err() {
             continue;