render: ActiveCameras resource and system

crates/bevy_render/src/base_render_graph/mod.rs

@@ -34,7 +34,7 @@ pub mod node {
     pub const SHARED_BUFFERS: &str = "shared_buffers";
 }
 
-pub mod uniform {
+pub mod camera {
     pub const CAMERA: &str = "Camera";
     pub const CAMERA2D: &str = "Camera2d";
 }
@@ -62,11 +62,11 @@ impl BaseRenderGraphBuilder for RenderGraph {
     fn add_base_graph(&mut self, config: &BaseRenderGraphConfig) -> &mut Self {
         self.add_node(node::TEXTURE_COPY, TextureCopyNode::default());
         if config.add_3d_camera {
-            self.add_system_node(node::CAMERA, CameraNode::new(uniform::CAMERA));
+            self.add_system_node(node::CAMERA, CameraNode::new(camera::CAMERA));
         }
 
         if config.add_2d_camera {
-            self.add_system_node(node::CAMERA2D, CameraNode::new(uniform::CAMERA2D));
+            self.add_system_node(node::CAMERA2D, CameraNode::new(camera::CAMERA2D));
         }
 
         self.add_node(node::SHARED_BUFFERS, SharedBuffersNode::default());

crates/bevy_render/src/camera/active_cameras.rs

@@ -0,0 +1,44 @@
+use crate::Camera;
+use legion::{
+    entity::Entity,
+    prelude::Read,
+    systems::{Query, ResMut, SubWorld},
+};
+use std::collections::HashMap;
+
+#[derive(Default)]
+pub struct ActiveCameras {
+    pub cameras: HashMap<String, Option<Entity>>,
+}
+
+impl ActiveCameras {
+    pub fn add(&mut self, name: &str) {
+        self.cameras.insert(name.to_string(), None);
+    }
+
+    pub fn set(&mut self, name: &str, entity: Entity) {
+        self.cameras.insert(name.to_string(), Some(entity));
+    }
+
+    pub fn get(&self, name: &str) -> Option<Entity> {
+        self.cameras.get(name).and_then(|e| e.clone())
+    }
+}
+
+pub fn active_cameras_system(
+    world: &mut SubWorld,
+    mut active_cameras: ResMut<ActiveCameras>,
+    query: &mut Query<Read<Camera>>,
+) {
+    for (name, active_camera) in active_cameras.cameras.iter_mut() {
+        if let None = active_camera {
+            for (camera_entity, camera) in query.iter_entities(world) {
+                if let Some(ref current_name) = camera.name {
+                    if current_name == name {
+                        *active_camera = Some(camera_entity);
+                    }
+                }
+            }
+        }
+    }
+}

crates/bevy_render/src/camera/mod.rs

@@ -1,7 +1,9 @@
+mod active_cameras;
 mod camera;
 mod projection;
 mod visible_entities;
 
+pub use active_cameras::*;
 pub use camera::*;
 pub use projection::*;
 pub use visible_entities::*;

crates/bevy_render/src/entity.rs

@@ -33,7 +33,7 @@ impl Default for PerspectiveCameraEntity {
     fn default() -> Self {
         PerspectiveCameraEntity {
             camera: Camera {
-                name: Some(base_render_graph::uniform::CAMERA.to_string()),
+                name: Some(base_render_graph::camera::CAMERA.to_string()),
                 ..Default::default()
             },
             perspective_projection: Default::default(),
@@ -81,7 +81,7 @@ impl Default for OrthographicCameraEntity {
     fn default() -> Self {
         OrthographicCameraEntity {
             camera: Camera {
-                name: Some(base_render_graph::uniform::CAMERA2D.to_string()),
+                name: Some(base_render_graph::camera::CAMERA2D.to_string()),
                 ..Default::default()
             },
             orthographic_projection: Default::default(),

crates/bevy_render/src/lib.rs

@@ -94,7 +94,12 @@ impl AppPlugin for RenderPlugin {
             .init_resource::<VertexBufferDescriptors>()
             .init_resource::<TextureResourceSystemState>()
             .init_resource::<AssetRenderResourceBindings>()
+            .init_resource::<ActiveCameras>()
             .add_system_to_stage(bevy_app::stage::PRE_UPDATE, clear_draw_system.system())
+            .add_system_to_stage(
+                bevy_app::stage::POST_UPDATE,
+                camera::active_cameras_system.system(),
+            )
             .add_system_to_stage(
                 bevy_app::stage::POST_UPDATE,
                 camera::camera_system::<OrthographicProjection>(),
@@ -125,6 +130,14 @@ impl AppPlugin for RenderPlugin {
             let resources = app.resources();
             let mut render_graph = resources.get_mut::<RenderGraph>().unwrap();
             render_graph.add_base_graph(config);
+            let mut active_cameras = resources.get_mut::<ActiveCameras>().unwrap();
+            if config.add_3d_camera {
+                active_cameras.add(base_render_graph::camera::CAMERA);
+            }
+
+            if config.add_2d_camera {
+                active_cameras.add(base_render_graph::camera::CAMERA2D);
+            }
         }
     }
 }

crates/bevy_render/src/render_graph/nodes/camera_node.rs

@@ -2,7 +2,7 @@ use crate::{
     render_graph::{CommandQueue, Node, ResourceSlots, SystemNode},
     render_resource::{BufferInfo, BufferUsage, RenderResourceBinding, RenderResourceBindings},
     renderer::{RenderContext, RenderResourceContext},
-    Camera,
+    ActiveCameras, Camera,
 };
 use bevy_core::bytes::AsBytes;
 
@@ -12,17 +12,17 @@ use std::borrow::Cow;
 
 pub struct CameraNode {
     command_queue: CommandQueue,
-    uniform_name: Cow<'static, str>,
+    camera_name: Cow<'static, str>,
 }
 
 impl CameraNode {
-    pub fn new<T>(uniform_name: T) -> Self
+    pub fn new<T>(camera_name: T) -> Self
     where
         T: Into<Cow<'static, str>>,
     {
         CameraNode {
             command_queue: Default::default(),
-            uniform_name: uniform_name.into(),
+            camera_name: camera_name.into(),
         }
     }
 }
@@ -44,13 +44,14 @@ impl SystemNode for CameraNode {
     fn get_system(&self) -> Box<dyn Schedulable> {
         let mut camera_buffer = None;
         let mut command_queue = self.command_queue.clone();
-        let uniform_name = self.uniform_name.clone();
+        let camera_name = self.camera_name.clone();
         (move |world: &mut SubWorld,
+               active_cameras: Res<ActiveCameras>,
                render_resource_context: Res<Box<dyn RenderResourceContext>>,
                // PERF: this write on RenderResourceAssignments will prevent this system from running in parallel
                // with other systems that do the same
                mut render_resource_bindings: ResMut<RenderResourceBindings>,
-               query: &mut Query<(Read<Camera>, Read<Transform>)>| {
+               _query: &mut Query<(Read<Camera>, Read<Transform>)>| {
             let render_resource_context = &**render_resource_context;
             if camera_buffer.is_none() {
                 let size = std::mem::size_of::<[[f32; 4]; 4]>();
@@ -60,7 +61,7 @@ impl SystemNode for CameraNode {
                     ..Default::default()
                 });
                 render_resource_bindings.set(
-                    &uniform_name,
+                    &camera_name,
                     RenderResourceBinding::Buffer {
                         buffer,
                         range: 0..size as u64,
@@ -69,34 +70,38 @@ impl SystemNode for CameraNode {
                 );
                 camera_buffer = Some(buffer);
             }
-            let matrix_size = std::mem::size_of::<[[f32; 4]; 4]>();
-            if let Some((camera, transform)) = query
-                .iter(world)
-                .find(|(camera, _)| camera.name.as_ref().map(|n| n.as_str()) == Some(&uniform_name))
+            let (camera, transform) = if let Some(camera_entity) = active_cameras.get(&camera_name)
             {
-                let camera_matrix: [f32; 16] =
-                    (camera.view_matrix * transform.value).to_cols_array();
+                (
+                    world.get_component::<Camera>(camera_entity).unwrap(),
+                    world.get_component::<Transform>(camera_entity).unwrap(),
+                )
+            } else {
+                return;
+            };
 
-                let tmp_buffer = render_resource_context.create_buffer_mapped(
-                    BufferInfo {
-                        size: matrix_size,
-                        buffer_usage: BufferUsage::COPY_SRC,
-                        ..Default::default()
-                    },
-                    &mut |data, _renderer| {
-                        data[0..matrix_size].copy_from_slice(camera_matrix.as_bytes());
-                    },
-                );
+            let matrix_size = std::mem::size_of::<[[f32; 4]; 4]>();
+            let camera_matrix: [f32; 16] = (camera.view_matrix * transform.value).to_cols_array();
 
-                command_queue.copy_buffer_to_buffer(
-                    tmp_buffer,
-                    0,
-                    camera_buffer.unwrap(),
-                    0,
-                    matrix_size as u64,
-                );
-                command_queue.free_buffer(tmp_buffer);
-            }
+            let tmp_buffer = render_resource_context.create_buffer_mapped(
+                BufferInfo {
+                    size: matrix_size,
+                    buffer_usage: BufferUsage::COPY_SRC,
+                    ..Default::default()
+                },
+                &mut |data, _renderer| {
+                    data[0..matrix_size].copy_from_slice(camera_matrix.as_bytes());
+                },
+            );
+
+            command_queue.copy_buffer_to_buffer(
+                tmp_buffer,
+                0,
+                camera_buffer.unwrap(),
+                0,
+                matrix_size as u64,
+            );
+            command_queue.free_buffer(tmp_buffer);
         })
         .system()
     }

crates/bevy_ui/src/render/mod.rs

@@ -4,7 +4,7 @@ use bevy_render::{
     pipeline::{state_descriptors::*, PipelineDescriptor},
     render_graph::{nodes::CameraNode, RenderGraph},
     shader::{Shader, ShaderStage, ShaderStages},
-    texture::TextureFormat,
+    texture::TextureFormat, ActiveCameras,
 };
 use legion::prelude::Resources;
 
@@ -60,7 +60,7 @@ pub mod node {
     pub const UI_CAMERA: &'static str = "ui_camera";
 }
 
-pub mod uniform {
+pub mod camera {
     pub const UI_CAMERA: &'static str = "UiCamera";
 }
 
@@ -70,12 +70,14 @@ pub trait UiRenderGraphBuilder {
 
 impl UiRenderGraphBuilder for RenderGraph {
     fn add_ui_graph(&mut self, resources: &Resources) -> &mut Self {
-        self.add_system_node(node::UI_CAMERA, CameraNode::new(uniform::UI_CAMERA));
+        self.add_system_node(node::UI_CAMERA, CameraNode::new(camera::UI_CAMERA));
         self.add_node_edge(node::UI_CAMERA, base_render_graph::node::MAIN_PASS)
             .unwrap();
         let mut pipelines = resources.get_mut::<Assets<PipelineDescriptor>>().unwrap();
         let mut shaders = resources.get_mut::<Assets<Shader>>().unwrap();
         pipelines.set(UI_PIPELINE_HANDLE, build_ui_pipeline(&mut shaders));
+        let mut active_cameras = resources.get_mut::<ActiveCameras>().unwrap();
+        active_cameras.add(camera::UI_CAMERA);
         self
     }
 }