Animation Editor UI (#20)

This PR adds a WIP timeline UI for animating elements in the scene.

### Implemented Features

* The timeline can be panned with MMB and zoomed with Ctrl + Mouse Wheel
* The timeline can be "scrubbed" by dragging the red "play-head" with
  LMB
* The timeline sidebar (displaying the list of tracks) can be resized by
  dragging on the edge of the sidebar
* Keyframes can be added by pressing the "Add Keyframe" CTA in the UI
* Keyframes can be selected for editing by clicking the diamond-shaped
  markers in the timeline
* Selected entities (including but not limited to keyframes) can be
  deleted by pressing the "Delete" key
* Keyframes can be moved temporally by dragging the diamond-shaped
  markers in the timeline

### Known issues

* Zooming the timeline in too far results in a soft-lock
* When zooming the timeline, the "transform origin" is currently
  centered on the `00:00` timestamp. For ease of use, it should center on
  the mouse cursor position instead.
* The timeline track-list is currently hard-coded to list the Camera and
  Camera Target. Clicking on these entries currently serves no useful
  purpose and may result in a crash.
* Keyframe markers in the timeline are not currently associated with
  entries in the track-list and simply appear vertically centered in the
  timeline view.
* Added keyframes currently record the position and orientation of the
  scene camera when added, and are rendered in the world with debug
  visualizations, but serve no useful purpose. Some design work is needed
  (both user-experience and architectural) to decide on a workflow for
  actually animating scene elements.
* Entity deletion cannot currently be undone/redone

studio/src/interaction/selection.rs

@@ -1,8 +1,11 @@
+use std::sync::Arc;
+
 use bevy::{prelude::*, render::mesh::skinning::SkinnedMesh};
 use bevy_mod_outline::{
     AutoGenerateOutlineNormalsPlugin, OutlineBundle, OutlinePlugin, OutlineVolume,
 };
 use bevy_mod_picking::{prelude::Pointer, selection::Select, PickableBundle};
+use space_editor::prelude::space_undo::{self, NewChange, RemovedEntity};
 
 use crate::{
     input::{self, Action, InputAction, Lifecycle},
@@ -13,7 +16,13 @@ pub struct SelectionPlugin;
 impl Plugin for SelectionPlugin {
     fn build(&self, app: &mut App) {
         app.add_plugins((OutlinePlugin, AutoGenerateOutlineNormalsPlugin))
-            .add_systems(Update, update_selection)
+            .add_systems(
+                Update,
+                (
+                    update_selection,
+                    process_delete_inputs.run_if(resource_exists::<Selection>()),
+                ),
+            )
             .add_systems(
                 PostUpdate,
                 draw_selection_outline.run_if(resource_changed_or_removed::<Selection>()),
@@ -149,6 +158,28 @@ fn update_selection(
     }
 }
 
+fn process_delete_inputs(
+    mut cmd: Commands,
+    mut er_input: EventReader<InputAction>,
+    mut ew_changes: EventWriter<space_undo::NewChange>,
+    r_selection: Res<Selection>,
+) {
+    if er_input.read().any(|action| {
+        matches!(
+            action,
+            InputAction(Lifecycle::Stop, Action::Selection(input::Selection::Delete))
+        )
+    }) {
+        let entity = **r_selection;
+
+        cmd.entity(entity).despawn_recursive();
+        cmd.remove_resource::<Selection>();
+        ew_changes.send(NewChange {
+            change: Arc::new(RemovedEntity { entity }),
+        });
+    }
+}
+
 fn draw_selection_outline(
     mut cmd: Commands,
     q_selected: Query<&Children, With<Selected>>,
@@ -193,7 +224,7 @@ mod wasm {
     use wasm_bindgen::prelude::*;
 
     use super::{Selected, Selection};
-    use crate::wasm::{self, StaticBuffer, WasmMessageBuffer};
+    use crate::wasm::{self, FromStr, StaticBuffer, WasmMessageBuffer};
 
     #[wasm_bindgen(typescript_custom_section)]
     const EVENT_DECLARATION: &str = r#"
@@ -207,7 +238,7 @@ export interface EntitySelectEvent extends CustomEvent {
 }
 
 declare global {
-    export interface HTMLElementEventMap {
+    export interface GlobalEventHandlersEventMap {
         "entity-select": EntitySelectEvent;
     }
 }
@@ -225,12 +256,7 @@ declare global {
 
     #[wasm_bindgen]
     pub fn select(entity: &str) {
-        let mut split = entity.split('v');
-        let index = split.next().unwrap().parse::<u32>().unwrap();
-        let generation = split.next().unwrap().parse::<u32>().unwrap();
-        let bits = (generation as u64) << 32 | index as u64;
-
-        let entity = Entity::from_bits(bits);
+        let entity = Entity::from_str(entity).unwrap();
         SELECTION_REQUEST.write_message(entity);
     }