Rename DefaultCameraView (#17235)

# Objective

The name `DefaultCameraView` is confusing and misleading:
* It isn't the default UI camera, which is either the camera with the
`IsDefaultUiCamera` marker component or, if no such camera is found, the
camera with the highest order which has the primary window as its render
target.
* It doesn't make sense to call it a "default", every active 2d and 3d
camera is given its own `DefaultCameraView`.
* The name doesn't make it clear that it's UI specific component.

## Solution

Rename `DefaultCameraView` to `UiCameraView`, add a doc comment for it
and rename a few other fields and variables.

## Migration Guide

`DefaultCameraView` has been renamed to `UiCameraView`

crates/bevy_ui/src/render/mod.rs

@@ -137,7 +137,7 @@ pub fn build_ui_render(app: &mut App) {
         .add_systems(
             ExtractSchedule,
             (
-                extract_default_ui_camera_view,
+                extract_ui_camera_view,
                 extract_uinode_background_colors.in_set(RenderUiSystem::ExtractBackgrounds),
                 extract_uinode_images.in_set(RenderUiSystem::ExtractImages),
                 extract_uinode_borders.in_set(RenderUiSystem::ExtractBorders),
@@ -532,10 +532,11 @@ const UI_CAMERA_FAR: f32 = 1000.0;
 const UI_CAMERA_TRANSFORM_OFFSET: f32 = -0.1;
 
 #[derive(Component)]
-pub struct DefaultCameraView(pub Entity);
+/// Entity id of the temporary render entity with the corresponding extracted UI view.
+pub struct UiCameraView(pub Entity);
 
 /// Extracts all UI elements associated with a camera into the render world.
-pub fn extract_default_ui_camera_view(
+pub fn extract_ui_camera_view(
     mut commands: Commands,
     mut transparent_render_phases: ResMut<ViewSortedRenderPhases<TransparentUi>>,
     query: Extract<
@@ -553,13 +554,13 @@ pub fn extract_default_ui_camera_view(
 ) {
     live_entities.clear();
 
-    for (entity, camera, ui_anti_alias, shadow_samples) in &query {
+    for (render_entity, camera, ui_anti_alias, shadow_samples) in &query {
         // ignore inactive cameras
         if !camera.is_active {
             commands
-                .get_entity(entity)
+                .get_entity(render_entity)
                 .expect("Camera entity wasn't synced.")
-                .remove::<(DefaultCameraView, UiAntiAlias, BoxShadowSamples)>();
+                .remove::<(UiCameraView, UiAntiAlias, BoxShadowSamples)>();
             continue;
         }
 
@@ -573,7 +574,7 @@ pub fn extract_default_ui_camera_view(
                 0.0,
                 UI_CAMERA_FAR,
             );
-            let default_camera_view = commands
+            let ui_camera_view = commands
                 .spawn((
                     ExtractedView {
                         clip_from_view: projection_matrix,
@@ -594,18 +595,18 @@ pub fn extract_default_ui_camera_view(
                 ))
                 .id();
             let mut entity_commands = commands
-                .get_entity(entity)
+                .get_entity(render_entity)
                 .expect("Camera entity wasn't synced.");
-            entity_commands.insert(DefaultCameraView(default_camera_view));
+            entity_commands.insert(UiCameraView(ui_camera_view));
             if let Some(ui_anti_alias) = ui_anti_alias {
                 entity_commands.insert(*ui_anti_alias);
             }
             if let Some(shadow_samples) = shadow_samples {
                 entity_commands.insert(*shadow_samples);
             }
-            transparent_render_phases.insert_or_clear(entity);
+            transparent_render_phases.insert_or_clear(render_entity);
 
-            live_entities.insert(entity);
+            live_entities.insert(render_entity);
         }
     }
 

crates/bevy_ui/src/render/render_pass.rs

@@ -1,7 +1,7 @@
 use core::ops::Range;
 
 use super::{ImageNodeBindGroups, UiBatch, UiMeta};
-use crate::DefaultCameraView;
+use crate::UiCameraView;
 use bevy_ecs::{
     prelude::*,
     system::{lifetimeless::*, SystemParamItem},
@@ -19,23 +19,24 @@ use bevy_render::{
 use tracing::error;
 
 pub struct UiPassNode {
-    ui_view_query: QueryState<(&'static ViewTarget, &'static ExtractedCamera), With<ExtractedView>>,
-    default_camera_view_query: QueryState<&'static DefaultCameraView>,
+    camera_view_query:
+        QueryState<(&'static ViewTarget, &'static ExtractedCamera), With<ExtractedView>>,
+    ui_camera_view_query: QueryState<&'static UiCameraView>,
 }
 
 impl UiPassNode {
     pub fn new(world: &mut World) -> Self {
         Self {
-            ui_view_query: world.query_filtered(),
-            default_camera_view_query: world.query(),
+            camera_view_query: world.query_filtered(),
+            ui_camera_view_query: world.query(),
         }
     }
 }
 
 impl Node for UiPassNode {
     fn update(&mut self, world: &mut World) {
-        self.ui_view_query.update_archetypes(world);
-        self.default_camera_view_query.update_archetypes(world);
+        self.camera_view_query.update_archetypes(world);
+        self.ui_camera_view_query.update_archetypes(world);
     }
 
     fn run(
@@ -56,19 +57,20 @@ impl Node for UiPassNode {
             return Ok(());
         };
 
-        let Ok((target, camera)) = self.ui_view_query.get_manual(world, input_view_entity) else {
+        let Ok((target, camera)) = self.camera_view_query.get_manual(world, input_view_entity)
+        else {
             return Ok(());
         };
         if transparent_phase.items.is_empty() {
             return Ok(());
         }
 
-        // use the "default" view entity if it is defined
-        let view_entity = if let Ok(default_view) = self
-            .default_camera_view_query
+        // use the UI view entity if it is defined
+        let view_entity = if let Ok(ui_camera_view) = self
+            .ui_camera_view_query
             .get_manual(world, input_view_entity)
         {
-            default_view.0
+            ui_camera_view.0
         } else {
             input_view_entity
         };