2 files changed, 72 insertions, 1 deletions

diff --git a/engine/src/windowing.rs b/engine/src/windowing.rs
index eae7616..be8dc39 100644
--- a/engine/src/windowing.rs
+++ b/engine/src/windowing.rs
@@ -8,7 +8,7 @@ use crossbeam_queue::ArrayQueue;
 use raw_window_handle::{DisplayHandle, HandleError, HasDisplayHandle, WindowHandle};
 use winit::application::ApplicationHandler;
 use winit::error::EventLoopError;
-use winit::event::{DeviceEvent, DeviceId, StartCause, WindowEvent};
+use winit::event::{DeviceEvent, DeviceId, MouseScrollDelta, StartCause, WindowEvent};
 use winit::event_loop::{
     ActiveEventLoop,
     ControlFlow as EventLoopControlFlow,
@@ -172,6 +172,14 @@ fn update_stuff(
         y: absolute_mouse_pos.1,
     };
 
+    let mouse_scroll_delta = context
+        .shared_state
+        .mouse_scroll_delta
+        .swap((0.0, 0.0), Ordering::Relaxed);
+
+    mouse.scroll_delta.hor_lines = mouse_scroll_delta.0 as f32;
+    mouse.scroll_delta.vert_lines = mouse_scroll_delta.1 as f32;
+
     keyboard.set_text_keys(iter_array_queue(&context.shared_state.text_keys));
 
     let Context {
@@ -649,6 +657,7 @@ struct SharedState
     message_to_app_queue: ArrayQueue<MessageToApp>,
     relative_mouse_pos_delta: AtomicTwoF64,
     absolute_mouse_pos: AtomicTwoF64,
+    mouse_scroll_delta: AtomicTwoF64,
     text_keys: ArrayQueue<char>,
     is_dropped: AtomicBool,
     thread_panicked: AtomicBool,
@@ -667,6 +676,7 @@ impl Default for SharedState
             message_to_app_queue: ArrayQueue::new(MESSAGE_TO_APP_QUEUE_SIZE),
             relative_mouse_pos_delta: AtomicTwoF64::new((0.0, 0.0)),
             absolute_mouse_pos: AtomicTwoF64::new((0.0, 0.0)),
+            mouse_scroll_delta: AtomicTwoF64::new((0.0, 0.0)),
             text_keys: ArrayQueue::new(TEXT_KEY_QUEUE_SIZE),
             is_dropped: AtomicBool::new(false),
             thread_panicked: AtomicBool::new(false),
@@ -979,6 +989,50 @@ impl ApplicationHandler for App
                         .store(delta, Ordering::Relaxed);
                 }
             }
+            DeviceEvent::MouseWheel { delta } => {
+                let line_delta = match delta {
+                    MouseScrollDelta::LineDelta(hor_lines, vert_lines) => {
+                        (hor_lines as f64, vert_lines as f64)
+                    }
+                    MouseScrollDelta::PixelDelta(pos_delta) => {
+                        let hor_lines = match pos_delta.x.partial_cmp(&0.0) {
+                            Some(std::cmp::Ordering::Greater) => 1.0,
+                            Some(std::cmp::Ordering::Less) => -1.0,
+                            _ => 0.0,
+                        };
+
+                        let vert_lines = match pos_delta.y.partial_cmp(&0.0) {
+                            Some(std::cmp::Ordering::Greater) => 1.0,
+                            Some(std::cmp::Ordering::Less) => -1.0,
+                            _ => 0.0,
+                        };
+
+                        (hor_lines, vert_lines)
+                    }
+                };
+
+                let curr_mouse_scroll_delta =
+                    self.shared_state.mouse_scroll_delta.load(Ordering::Relaxed);
+
+                if self
+                    .shared_state
+                    .mouse_scroll_delta
+                    .compare_exchange(
+                        curr_mouse_scroll_delta,
+                        (
+                            curr_mouse_scroll_delta.0 + line_delta.0,
+                            curr_mouse_scroll_delta.1 + line_delta.1,
+                        ),
+                        Ordering::Relaxed,
+                        Ordering::Relaxed,
+                    )
+                    .is_err()
+                {
+                    self.shared_state
+                        .mouse_scroll_delta
+                        .store(line_delta, Ordering::Relaxed);
+                }
+            }
             _ => {}
         }
     }
diff --git a/engine/src/windowing/mouse.rs b/engine/src/windowing/mouse.rs
index 649036a..abe2ab7 100644
--- a/engine/src/windowing/mouse.rs
+++ b/engine/src/windowing/mouse.rs
@@ -17,6 +17,23 @@ pub struct Mouse
     /// Coordinates in pixels relative to the top-left corner of the window. May have
     /// been affected by cursor acceleration
     pub position: PhysicalPosition<f64>,
+
+    pub scroll_delta: ScrollDelta,
+}
+
+#[derive(Debug, Clone, Default)]
+pub struct ScrollDelta
+{
+    pub vert_lines: f32,
+    pub hor_lines: f32,
+}
+
+impl ScrollDelta
+{
+    pub fn is_zero(&self) -> bool
+    {
+        self.vert_lines == 0.0 && self.hor_lines == 0.0
+    }
 }
 
 /// Mouse buttons.