Add dialog scrolling, docstrings on systems

flake.nix

@@ -47,6 +47,8 @@
                 # Rustup
                 rustup
                 wayland # To use the wayland feature
+                # Bug tracking
+                git-bug
               ];
             LD_LIBRARY_PATH = lib.makeLibraryPath [
                 alsa-lib

src/bin/trees/main.rs

@@ -12,14 +12,22 @@ fn main() {
         )
         .add_systems(
             Update,
+            (
                 dialog_engine.run_if(input_just_pressed(KeyCode::KeyN)),
+                mouse_wheel_scroll.run_if(on_event::<MouseWheel>),
+                auto_scroll.run_if(any_component_added::<DialogOption>)
+            ),
         )
         .run();
 }
 
+/// Tree marker component
 #[derive(Component)]
 struct Tree;
 
+/// Initialize the trees, currently placeholders
+/// Trees are 2d cards in a 3d world for flexibility
+/// Might move fully 2d if the art style allows it
 fn init_trees(
     mut commands: Commands,
     mut meshes: ResMut<Assets<Mesh>>,
@@ -88,9 +96,11 @@ fn init_trees(
     }
 }
 
+/// Dialog box marker component
 #[derive(Component)]
 struct DialogBox;
 
+/// Initialize the UI which consists soley of a dialog box (for now?)
 fn init_ui(mut commands: Commands) {
     commands.spawn((
         DialogBox,
@@ -104,11 +114,15 @@ fn init_ui(mut commands: Commands) {
             margin: UiRect::all(Val::Percent(1.0)),
             padding: UiRect::all(Val::Percent(1.0)),
             flex_direction: FlexDirection::Column,
+            // Scroll on the Y axis
+            overflow: Overflow::scroll_y(),
             ..default()
         },
     ));
 }
 
+/// On startup move the camera to a suitable position
+/// This should be mostly static for the entire game
 fn position_camera(mut query: Query<&mut Transform, (With<Camera>, With<Camera3d>)>) {
     use std::f32::consts::PI;
 
@@ -118,12 +132,15 @@ fn position_camera(mut query: Query<&mut Transform, (With<Camera>, With<Camera3d
     })
 }
 
+/// A possible line of dialog the user can choose
 #[derive(Component)]
 struct DialogOption;
 
+/// A line of dialog which has been chosen, so is permanent
 #[derive(Component)]
 struct DialogLine;
 
+/// System which puts DialogOptions into the DialogBox
 fn dialog_engine(
     mut commands: Commands,
     dialog_box: Single<Entity, With<DialogBox>>,
@@ -152,6 +169,10 @@ fn dialog_engine(
     *idx += 1;
 }
 
+/// When a dialog option is chosen (clicked on) we do the following:
+/// 1. Remove the Button and DialogOption components from that entity
+/// 2. Insert the DialogLine component to that entity
+/// 3. Remove all other DialogOptions from the DialogBox
 fn choose_dialog(trigger: Trigger<Pointer<Click>>, mut commands: Commands) {
     info!("Choosing dialog {:?}", trigger.target());
     commands
@@ -160,3 +181,31 @@ fn choose_dialog(trigger: Trigger<Pointer<Click>>, mut commands: Commands) {
         .remove::<DialogOption>()
         .insert(DialogLine);
 }
+
+/// Allows user to scroll (with mouse whell) through old dialog
+fn mouse_wheel_scroll(
+    mut events: EventReader<MouseWheel>,
+    mut scroll_position: Query<&mut ScrollPosition>,
+) {
+    events.read().for_each(|MouseWheel { unit, y, .. }| {
+        let offset_y = match unit {
+            MouseScrollUnit::Line => 10.0 * y,
+            MouseScrollUnit::Pixel => 1.0 * y,
+        };
+        scroll_position
+            .iter_mut()
+            .for_each(|mut pos| pos.offset_y += offset_y);
+    });
+}
+
+/// Automatically scrolls dialog when a new batch of options are added
+fn auto_scroll(
+    added: Query<Entity, Added<DialogOption>>,
+    mut scroll_positions: Query<&mut ScrollPosition>,
+) {
+    debug_assert!(!added.is_empty(), "Should only scroll when dialog options are added");
+
+    scroll_positions.iter_mut().for_each(|mut sp| {
+        sp.offset_y = f32::MAX;
+    });
+}

src/lib.rs

@@ -12,8 +12,13 @@ pub use std::fmt::Display;
 pub use bevy::{
     asset::LoadState,
     color::palettes::css::{BLACK, BLUE, GREEN, RED, WHITE},
-    input::common_conditions::{input_just_pressed, input_pressed},
+    input::{
-    input::{ButtonState, keyboard::KeyboardInput, mouse::MouseMotion},
+        ButtonState,
+        common_conditions::{input_just_pressed, input_pressed},
+        keyboard::KeyboardInput,
+        mouse::MouseMotion,
+        mouse::{MouseScrollUnit, MouseWheel},
+    },
     prelude::*,
 };
 pub use bevy_rapier3d::prelude::*;