Visibilty Inheritance, universal ComputedVisibility and RenderLayers …

…support (#5310)

# Objective

Fixes #4907. Fixes #838. Fixes #5089.
Supersedes #5146. Supersedes #2087. Supersedes #865. Supersedes #5114

Visibility is currently entirely local. Set a parent entity to be invisible, and the children are still visible. This makes it hard for users to hide entire hierarchies of entities.

Additionally, the semantics of `Visibility` vs `ComputedVisibility` are inconsistent across entity types. 3D meshes use `ComputedVisibility` as the "definitive" visibility component, with `Visibility` being just one data source. Sprites just use `Visibility`, which means they can't feed off of `ComputedVisibility` data, such as culling information, RenderLayers, and (added in this pr) visibility inheritance information.

## Solution

Splits `ComputedVisibilty::is_visible` into `ComputedVisibilty::is_visible_in_view` and `ComputedVisibilty::is_visible_in_hierarchy`. For each visible entity, `is_visible_in_hierarchy` is computed by propagating visibility down the hierarchy. The `ComputedVisibility::is_visible()` function combines these two booleans for the canonical "is this entity visible" function.

Additionally, all entities that have `Visibility` now also have `ComputedVisibility`.  Sprites, Lights, and UI entities now use `ComputedVisibility` when appropriate.

This means that in addition to visibility inheritance, everything using Visibility now also supports RenderLayers. Notably, Sprites (and other 2d objects) now support `RenderLayers` and work properly across multiple views.

Also note that this does increase the amount of work done per sprite. Bevymark with 100,000 sprites on `main` runs in `0.017612` seconds and this runs in `0.01902`. That is certainly a gap, but I believe the api consistency and extra functionality this buys us is worth it. See [this thread](#5146 (comment)) for more info. Note that #5146 in combination with #5114 _are_ a viable alternative to this PR and _would_ perform better, but that comes at the cost of api inconsistencies and doing visibility calculations in the "wrong" place. The current visibility system does have potential for performance improvements. I would prefer to evolve that one system as a whole rather than doing custom hacks / different behaviors for each feature slice.

Here is a "split screen" example where the left camera uses RenderLayers to filter out the blue sprite.

![image](https://user-images.githubusercontent.com/2694663/178814868-2e9a2173-bf8c-4c79-8815-633899d492c3.png)


Note that this builds directly on #5146 and that @james7132 deserves the credit for the baseline visibility inheritance work. This pr moves the inherited visibility field into `ComputedVisibility`, then does the additional work of porting everything to `ComputedVisibility`. See my [comments here](#5146 (comment)) for rationale. 

## Follow up work

* Now that lights use ComputedVisibility, VisibleEntities now includes "visible lights" in the entity list. Functionally not a problem as we use queries to filter the list down in the desired context. But we should consider splitting this out into a separate`VisibleLights` collection for both clarity and performance reasons. And _maybe_ even consider scoping `VisibleEntities` down to `VisibleMeshes`?.
* Investigate alternative sprite rendering impls (in combination with visibility system tweaks) that avoid re-generating a per-view fixedbitset of visible entities every frame, then checking each ExtractedEntity. This is where most of the performance overhead lives. Ex: we could generate ExtractedEntities per-view using the VisibleEntities list, avoiding the need for the bitset.
* Should ComputedVisibility use bitflags under the hood? This would cut down on the size of the component, potentially speed up the `is_visible()` function, and allow us to cheaply expand ComputedVisibility with more data (ex: split out local visibility and parent visibility, add more culling classes, etc).
---

## Changelog

* ComputedVisibility now takes hierarchy visibility into account.
* 2D, UI and Light entities now use the ComputedVisibility component.

## Migration Guide

If you were previously reading `Visibility::is_visible` as the "actual visibility" for sprites or lights, use `ComputedVisibilty::is_visible()` instead:

```rust
// before (0.7)
fn system(query: Query<&Visibility>) {
  for visibility in query.iter() {
    if visibility.is_visible {
       log!("found visible entity");
    }
  }
}

// after (0.8)
fn system(query: Query<&ComputedVisibility>) {
  for visibility in query.iter() {
    if visibility.is_visible() {
       log!("found visible entity");
    }
  }
}
``` 


Co-authored-by: Carter Anderson <mcanders1@gmail.com>

crates/bevy_pbr/src/bundle.rs

@@ -73,6 +73,8 @@ pub struct PointLightBundle {
     pub global_transform: GlobalTransform,
     /// Enables or disables the light
     pub visibility: Visibility,
+    /// Algorithmically-computed indication of whether an entity is visible and should be extracted for rendering
+    pub computed_visibility: ComputedVisibility,
 }
 
 /// A component bundle for spot light entities
@@ -85,6 +87,8 @@ pub struct SpotLightBundle {
     pub global_transform: GlobalTransform,
     /// Enables or disables the light
     pub visibility: Visibility,
+    /// Algorithmically-computed indication of whether an entity is visible and should be extracted for rendering
+    pub computed_visibility: ComputedVisibility,
 }
 
 /// A component bundle for [`DirectionalLight`] entities.
@@ -97,4 +101,6 @@ pub struct DirectionalLightBundle {
     pub global_transform: GlobalTransform,
     /// Enables or disables the light
     pub visibility: Visibility,
+    /// Algorithmically-computed indication of whether an entity is visible and should be extracted for rendering
+    pub computed_visibility: ComputedVisibility,
 }

crates/bevy_pbr/src/lib.rs

@@ -150,13 +150,16 @@ impl Plugin for PbrPlugin {
                 assign_lights_to_clusters
                     .label(SimulationLightSystems::AssignLightsToClusters)
                     .after(TransformSystem::TransformPropagate)
+                    .after(VisibilitySystems::CheckVisibility)
                     .after(CameraUpdateSystem)
                     .after(ModifiesWindows),
             )
             .add_system_to_stage(
                 CoreStage::PostUpdate,
                 update_directional_light_frusta
                     .label(SimulationLightSystems::UpdateLightFrusta)
+                    // This must run after CheckVisibility because it relies on ComputedVisibility::is_visible()
+                    .after(VisibilitySystems::CheckVisibility)
                     .after(TransformSystem::TransformPropagate),
             )
             .add_system_to_stage(

crates/bevy_pbr/src/light.rs

@@ -10,7 +10,7 @@ use bevy_render::{
     primitives::{Aabb, CubemapFrusta, Frustum, Plane, Sphere},
     render_resource::BufferBindingType,
     renderer::RenderDevice,
-    view::{ComputedVisibility, RenderLayers, Visibility, VisibleEntities},
+    view::{ComputedVisibility, RenderLayers, VisibleEntities},
 };
 use bevy_transform::components::GlobalTransform;
 use bevy_utils::tracing::warn;
@@ -793,8 +793,8 @@ pub(crate) fn assign_lights_to_clusters(
         &mut Clusters,
         Option<&mut VisiblePointLights>,
     )>,
-    point_lights_query: Query<(Entity, &GlobalTransform, &PointLight, &Visibility)>,
-    spot_lights_query: Query<(Entity, &GlobalTransform, &SpotLight, &Visibility)>,
+    point_lights_query: Query<(Entity, &GlobalTransform, &PointLight, &ComputedVisibility)>,
+    spot_lights_query: Query<(Entity, &GlobalTransform, &SpotLight, &ComputedVisibility)>,
     mut lights: Local<Vec<PointLightAssignmentData>>,
     mut cluster_aabb_spheres: Local<Vec<Option<Sphere>>>,
     mut max_point_lights_warning_emitted: Local<bool>,
@@ -811,7 +811,7 @@ pub(crate) fn assign_lights_to_clusters(
     lights.extend(
         point_lights_query
             .iter()
-            .filter(|(.., visibility)| visibility.is_visible)
+            .filter(|(.., visibility)| visibility.is_visible())
             .map(
                 |(entity, transform, point_light, _visibility)| PointLightAssignmentData {
                     entity,
@@ -826,7 +826,7 @@ pub(crate) fn assign_lights_to_clusters(
     lights.extend(
         spot_lights_query
             .iter()
-            .filter(|(.., visibility)| visibility.is_visible)
+            .filter(|(.., visibility)| visibility.is_visible())
             .map(
                 |(entity, transform, spot_light, _visibility)| PointLightAssignmentData {
                     entity,
@@ -1415,7 +1415,7 @@ pub fn update_directional_light_frusta(
             &GlobalTransform,
             &DirectionalLight,
             &mut Frustum,
-            &Visibility,
+            &ComputedVisibility,
         ),
         Or<(Changed<GlobalTransform>, Changed<DirectionalLight>)>,
     >,
@@ -1424,7 +1424,7 @@ pub fn update_directional_light_frusta(
         // The frustum is used for culling meshes to the light for shadow mapping
         // so if shadow mapping is disabled for this light, then the frustum is
         // not needed.
-        if !directional_light.shadows_enabled || !visibility.is_visible {
+        if !directional_light.shadows_enabled || !visibility.is_visible() {
             continue;
         }
 
@@ -1541,45 +1541,43 @@ pub fn check_light_mesh_visibility(
             &Frustum,
             &mut VisibleEntities,
             Option<&RenderLayers>,
-            &Visibility,
+            &ComputedVisibility,
         ),
         Without<SpotLight>,
     >,
     mut visible_entity_query: Query<
         (
             Entity,
-            &Visibility,
             &mut ComputedVisibility,
             Option<&RenderLayers>,
             Option<&Aabb>,
             Option<&GlobalTransform>,
         ),
-        Without<NotShadowCaster>,
+        (Without<NotShadowCaster>, Without<DirectionalLight>),
     >,
 ) {
-    // Directonal lights
-    for (directional_light, frustum, mut visible_entities, maybe_view_mask, visibility) in
-        &mut directional_lights
+    // Directional lights
+    for (
+        directional_light,
+        frustum,
+        mut visible_entities,
+        maybe_view_mask,
+        light_computed_visibility,
+    ) in &mut directional_lights
     {
         visible_entities.entities.clear();
 
         // NOTE: If shadow mapping is disabled for the light then it must have no visible entities
-        if !directional_light.shadows_enabled || !visibility.is_visible {
+        if !directional_light.shadows_enabled || !light_computed_visibility.is_visible() {
             continue;
         }
 
         let view_mask = maybe_view_mask.copied().unwrap_or_default();
 
-        for (
-            entity,
-            visibility,
-            mut computed_visibility,
-            maybe_entity_mask,
-            maybe_aabb,
-            maybe_transform,
-        ) in &mut visible_entity_query
+        for (entity, mut computed_visibility, maybe_entity_mask, maybe_aabb, maybe_transform) in
+            &mut visible_entity_query
         {
-            if !visibility.is_visible {
+            if !computed_visibility.is_visible_in_hierarchy() {
                 continue;
             }
 
@@ -1595,7 +1593,7 @@ pub fn check_light_mesh_visibility(
                 }
             }
 
-            computed_visibility.is_visible = true;
+            computed_visibility.set_visible_in_view();
             visible_entities.entities.push(entity);
         }
 
@@ -1631,14 +1629,13 @@ pub fn check_light_mesh_visibility(
 
                 for (
                     entity,
-                    visibility,
                     mut computed_visibility,
                     maybe_entity_mask,
                     maybe_aabb,
                     maybe_transform,
                 ) in &mut visible_entity_query
                 {
-                    if !visibility.is_visible {
+                    if !computed_visibility.is_visible_in_hierarchy() {
                         continue;
                     }
 
@@ -1660,12 +1657,12 @@ pub fn check_light_mesh_visibility(
                             .zip(cubemap_visible_entities.iter_mut())
                         {
                             if frustum.intersects_obb(aabb, &model_to_world, true) {
-                                computed_visibility.is_visible = true;
+                                computed_visibility.set_visible_in_view();
                                 visible_entities.entities.push(entity);
                             }
                         }
                     } else {
-                        computed_visibility.is_visible = true;
+                        computed_visibility.set_visible_in_view();
                         for visible_entities in cubemap_visible_entities.iter_mut() {
                             visible_entities.entities.push(entity);
                         }
@@ -1695,14 +1692,13 @@ pub fn check_light_mesh_visibility(
 
                 for (
                     entity,
-                    visibility,
                     mut computed_visibility,
                     maybe_entity_mask,
                     maybe_aabb,
                     maybe_transform,
                 ) in visible_entity_query.iter_mut()
                 {
-                    if !visibility.is_visible {
+                    if !computed_visibility.is_visible_in_hierarchy() {
                         continue;
                     }
 
@@ -1720,11 +1716,11 @@ pub fn check_light_mesh_visibility(
                         }
 
                         if frustum.intersects_obb(aabb, &model_to_world, true) {
-                            computed_visibility.is_visible = true;
+                            computed_visibility.set_visible_in_view();
                             visible_entities.entities.push(entity);
                         }
                     } else {
-                        computed_visibility.is_visible = true;
+                        computed_visibility.set_visible_in_view();
                         visible_entities.entities.push(entity);
                     }
                 }

crates/bevy_pbr/src/render/light.rs

@@ -26,7 +26,8 @@ use bevy_render::{
     renderer::{RenderContext, RenderDevice, RenderQueue},
     texture::*,
     view::{
-        ExtractedView, ViewUniform, ViewUniformOffset, ViewUniforms, Visibility, VisibleEntities,
+        ComputedVisibility, ExtractedView, ViewUniform, ViewUniformOffset, ViewUniforms,
+        VisibleEntities,
     },
     Extract,
 };
@@ -411,16 +412,30 @@ pub fn extract_lights(
     point_light_shadow_map: Extract<Res<PointLightShadowMap>>,
     directional_light_shadow_map: Extract<Res<DirectionalLightShadowMap>>,
     global_point_lights: Extract<Res<GlobalVisiblePointLights>>,
-    point_lights: Extract<Query<(&PointLight, &CubemapVisibleEntities, &GlobalTransform)>>,
-    spot_lights: Extract<Query<(&SpotLight, &VisibleEntities, &GlobalTransform)>>,
+    point_lights: Extract<
+        Query<(
+            &PointLight,
+            &CubemapVisibleEntities,
+            &GlobalTransform,
+            &ComputedVisibility,
+        )>,
+    >,
+    spot_lights: Extract<
+        Query<(
+            &SpotLight,
+            &VisibleEntities,
+            &GlobalTransform,
+            &ComputedVisibility,
+        )>,
+    >,
     directional_lights: Extract<
         Query<
             (
                 Entity,
                 &DirectionalLight,
                 &VisibleEntities,
                 &GlobalTransform,
-                &Visibility,
+                &ComputedVisibility,
             ),
             Without<SpotLight>,
         >,
@@ -447,7 +462,12 @@ pub fn extract_lights(
 
     let mut point_lights_values = Vec::with_capacity(*previous_point_lights_len);
     for entity in global_point_lights.iter().copied() {
-        if let Ok((point_light, cubemap_visible_entities, transform)) = point_lights.get(entity) {
+        if let Ok((point_light, cubemap_visible_entities, transform, visibility)) =
+            point_lights.get(entity)
+        {
+            if !visibility.is_visible() {
+                continue;
+            }
             // TODO: This is very much not ideal. We should be able to re-use the vector memory.
             // However, since exclusive access to the main world in extract is ill-advised, we just clone here.
             let render_cubemap_visible_entities = cubemap_visible_entities.clone();
@@ -481,7 +501,10 @@ pub fn extract_lights(
 
     let mut spot_lights_values = Vec::with_capacity(*previous_spot_lights_len);
     for entity in global_point_lights.iter().copied() {
-        if let Ok((spot_light, visible_entities, transform)) = spot_lights.get(entity) {
+        if let Ok((spot_light, visible_entities, transform, visibility)) = spot_lights.get(entity) {
+            if !visibility.is_visible() {
+                continue;
+            }
             // TODO: This is very much not ideal. We should be able to re-use the vector memory.
             // However, since exclusive access to the main world in extract is ill-advised, we just clone here.
             let render_visible_entities = visible_entities.clone();
@@ -522,7 +545,7 @@ pub fn extract_lights(
     for (entity, directional_light, visible_entities, transform, visibility) in
         directional_lights.iter()
     {
-        if !visibility.is_visible {
+        if !visibility.is_visible() {
             continue;
         }
 

crates/bevy_pbr/src/render/mesh.rs

@@ -139,7 +139,7 @@ pub fn extract_meshes(
 ) {
     let mut caster_commands = Vec::with_capacity(*prev_caster_commands_len);
     let mut not_caster_commands = Vec::with_capacity(*prev_not_caster_commands_len);
-    let visible_meshes = meshes_query.iter().filter(|(_, vis, ..)| vis.is_visible);
+    let visible_meshes = meshes_query.iter().filter(|(_, vis, ..)| vis.is_visible());
 
     for (entity, _, transform, handle, not_receiver, not_caster) in visible_meshes {
         let transform = transform.compute_matrix();
@@ -224,7 +224,7 @@ pub fn extract_skinned_meshes(
     let mut last_start = 0;
 
     for (entity, computed_visibility, skin) in query.iter() {
-        if !computed_visibility.is_visible {
+        if !computed_visibility.is_visible() {
             continue;
         }
         // PERF: This can be expensive, can we move this to prepare?

crates/bevy_render/Cargo.toml

@@ -34,6 +34,7 @@ bevy_core = { path = "../bevy_core", version = "0.8.0-dev" }
 bevy_derive = { path = "../bevy_derive", version = "0.8.0-dev" }
 bevy_ecs = { path = "../bevy_ecs", version = "0.8.0-dev" }
 bevy_encase_derive = { path = "../bevy_encase_derive", version = "0.8.0-dev" }
+bevy_hierarchy = { path = "../bevy_hierarchy", version = "0.8.0-dev" }
 bevy_log = { path = "../bevy_log", version = "0.8.0-dev" }
 bevy_math = { path = "../bevy_math", version = "0.8.0-dev" }
 bevy_mikktspace = { path = "../bevy_mikktspace", version = "0.8.0-dev" }

crates/bevy_render/src/extract_component.rs

@@ -200,7 +200,7 @@ fn extract_visible_components<C: ExtractComponent>(
 ) {
     let mut values = Vec::with_capacity(*previous_len);
     for (entity, computed_visibility, query_item) in query.iter_mut() {
-        if computed_visibility.is_visible {
+        if computed_visibility.is_visible() {
             values.push((entity, (C::extract_component(query_item),)));
         }
     }