From 654dd32fce0a4bce11f2aa13c159c85d7ac7e75b Mon Sep 17 00:00:00 2001
From: Elijah Voigt <elijah.caine.mv@gmail.com>
Date: Mon, 18 Aug 2025 12:21:58 -0700
Subject: [PATCH] Parallax almost wraps correctly!

---
 examples/parallax.rs | 62 ++++++++++++++++++++++++++++++++++++++++++++
 src/parallax.rs      |  7 +++--
 2 files changed, 65 insertions(+), 4 deletions(-)

diff --git a/examples/parallax.rs b/examples/parallax.rs
index f302a9e..6b95dea 100644
--- a/examples/parallax.rs
+++ b/examples/parallax.rs
@@ -10,6 +10,7 @@ fn main() {
         .add_systems(Startup, spawn_background)
         .add_systems(Update, move_camera)
         .add_systems(Update, parallax_gizmos)
+        .add_systems(Update, wrap_parallax_items.run_if(any_component_changed::<ViewVisibility>))
         .run();
 }
 
@@ -87,3 +88,64 @@ fn parallax_gizmos(mut gizmos: Gizmos, q: Query<&Transform, With<ParallaxDepth>>
             .outer_edges();
     });
 }
+
+fn wrap_parallax_items(
+    mut items: Query<(&mut Transform, &GlobalTransform, &ViewVisibility), (With<ParallaxDepth>, Without<Camera2d>, Changed<ViewVisibility>)>,
+    camera: Single<(&Camera, &GlobalTransform), With<Camera2d>>,
+    window: Single<&Window>,
+) {
+    if !items.is_empty() {
+        let (cam, cam_gt) = *camera;
+
+        // get the window size in world space
+        let window_size_in_world_space = {
+            let top_left = cam.viewport_to_world_2d(cam_gt, Vec2::ZERO).unwrap();
+            let bottom_right = cam.viewport_to_world_2d(cam_gt, window.size()).unwrap();
+
+            Vec2::abs(Vec2::new(bottom_right.x - top_left.x, bottom_right.y - top_left.y))
+        };
+        info!("Window size: {:?}", window_size_in_world_space);
+
+        // for each item in the paralax items
+        items.iter_mut().for_each(|(mut t, gt, v)| {
+            if !v.get() {
+                info!("The item is not visible");
+
+                // Get the total size (window + scale)
+                let total_size = window_size_in_world_space + t.scale.truncate();
+                info!("Window size: {:?} | Object size: {:?}", window_size_in_world_space, t.scale().truncate());
+                info!("Total size: {:?}", total_size);
+
+                // Double check that item is out of bounds
+                let bounds_check = Vec2::abs(cam_gt.translation().truncate() - gt.translation().truncate());
+                let out_of_bounds = (total_size / 2.0) - bounds_check;
+                info!("Bounds check {:?}", bounds_check);
+                info!("Out of bounds: {:?}", out_of_bounds);
+                if out_of_bounds.x < 0.0 {
+                    info!("Object is actually out of bounds horizontally");
+                    // determine if should move to the left or right relative to camera
+                    let move_right = cam_gt.translation().x > gt.translation().x;
+
+                    // move left or right
+                    if move_right {
+                        t.translation.x += total_size.x;
+                    } else {
+                        t.translation.x -= total_size.x;
+                    }
+                }
+                if out_of_bounds.y < 0.0 {
+                    info!("Object is actually out of bounds vertically");
+                    let move_up = cam_gt.translation().y > gt.translation().y;
+
+                    // move up or down
+                    if move_up {
+                        t.translation.y += total_size.y;
+                    } else {
+                        t.translation.y -= total_size.y;
+                    }
+                }
+                info!("Moved to {:?}", t.translation);
+            }
+        });
+    }
+}
diff --git a/src/parallax.rs b/src/parallax.rs
index ad799c4..b77d344 100644
--- a/src/parallax.rs
+++ b/src/parallax.rs
@@ -24,13 +24,12 @@ impl Plugin for ParallaxPlugin {
 pub struct ParallaxDepth(pub f32);
 
 fn move_parallax_items(
-    mut q: Query<(&mut Transform, &ParallaxDepth), Without<Camera>>,
-    window: Single<&Window>,
-    camera: Single<(&Camera, &Transform, &GlobalTransform), (With<Camera2d>, Changed<Transform>)>,
+    mut q: Query<(&mut Transform, &ParallaxDepth), Without<Camera2d>>,
+    camera: Single<&Transform, (With<Camera2d>, Changed<Transform>)>,
     mut prev_camera_pos: Local<Vec2>,
 ) {
     // Unpack the camera data
-    let (cam, cam_t, cam_gt) = *camera;
+    let cam_t = *camera;
 
     // Calculate how far the camera moved since the last update
     let delta = cam_t.translation.truncate() - *prev_camera_pos;