Allow to reuse the same RenderPass for multiple RenderPhases (#7043)

# Objective

- The recently merged PR #7013 does not allow multiple `RenderPhase`s to share the same `RenderPass`.
- Due to the introduced overhead we want to minimize the number of `RenderPass`es recorded during each frame.

## Solution

- Take a constructed `TrackedRenderPass` instead of a `RenderPassDiscriptor` as a parameter to the `RenderPhase::render` method.

---

## Changelog

To enable multiple `RenderPhases` to share the same `TrackedRenderPass`,
the `RenderPhase::render` signature has changed.

```rust
pub fn render<'w>(
  &self,
  render_pass: &mut TrackedRenderPass<'w>,
  world: &'w World,
  view: Entity)
```


Co-authored-by: Kurt Kühnert <[email protected]>

Author: kurtkuehnert

crates/bevy_core_pipeline/src/core_2d/main_pass_2d_node.rs

@@ -3,6 +3,7 @@ use crate::{
     core_2d::{camera_2d::Camera2d, Transparent2d},
 };
 use bevy_ecs::prelude::*;
+use bevy_render::render_phase::TrackedRenderPass;
 use bevy_render::{
     camera::ExtractedCamera,
     render_graph::{Node, NodeRunError, RenderGraphContext, SlotInfo, SlotType},
@@ -77,13 +78,16 @@ impl Node for MainPass2dNode {
                 depth_stencil_attachment: None,
             };
 
-            transparent_phase.render(
-                world,
-                render_context,
-                view_entity,
-                camera.viewport.as_ref(),
-                pass_descriptor,
-            );
+            let render_pass = render_context
+                .command_encoder
+                .begin_render_pass(&pass_descriptor);
+            let mut render_pass = TrackedRenderPass::new(render_pass);
+
+            if let Some(viewport) = camera.viewport.as_ref() {
+                render_pass.set_camera_viewport(viewport);
+            }
+
+            transparent_phase.render(&mut render_pass, world, view_entity);
         }
 
         // WebGL2 quirk: if ending with a render pass with a custom viewport, the viewport isn't

crates/bevy_core_pipeline/src/core_3d/main_pass_3d_node.rs

@@ -3,6 +3,7 @@ use crate::{
     core_3d::{AlphaMask3d, Camera3d, Opaque3d, Transparent3d},
 };
 use bevy_ecs::prelude::*;
+use bevy_render::render_phase::TrackedRenderPass;
 use bevy_render::{
     camera::ExtractedCamera,
     render_graph::{Node, NodeRunError, RenderGraphContext, SlotInfo, SlotType},
@@ -95,13 +96,16 @@ impl Node for MainPass3dNode {
                 }),
             };
 
-            opaque_phase.render(
-                world,
-                render_context,
-                view_entity,
-                camera.viewport.as_ref(),
-                pass_descriptor,
-            );
+            let render_pass = render_context
+                .command_encoder
+                .begin_render_pass(&pass_descriptor);
+            let mut render_pass = TrackedRenderPass::new(render_pass);
+
+            if let Some(viewport) = camera.viewport.as_ref() {
+                render_pass.set_camera_viewport(viewport);
+            }
+
+            opaque_phase.render(&mut render_pass, world, view_entity);
         }
 
         if !alpha_mask_phase.items.is_empty() {
@@ -127,13 +131,16 @@ impl Node for MainPass3dNode {
                 }),
             };
 
-            alpha_mask_phase.render(
-                world,
-                render_context,
-                view_entity,
-                camera.viewport.as_ref(),
-                pass_descriptor,
-            );
+            let render_pass = render_context
+                .command_encoder
+                .begin_render_pass(&pass_descriptor);
+            let mut render_pass = TrackedRenderPass::new(render_pass);
+
+            if let Some(viewport) = camera.viewport.as_ref() {
+                render_pass.set_camera_viewport(viewport);
+            }
+
+            alpha_mask_phase.render(&mut render_pass, world, view_entity);
         }
 
         if !transparent_phase.items.is_empty() {
@@ -164,13 +171,16 @@ impl Node for MainPass3dNode {
                 }),
             };
 
-            transparent_phase.render(
-                world,
-                render_context,
-                view_entity,
-                camera.viewport.as_ref(),
-                pass_descriptor,
-            );
+            let render_pass = render_context
+                .command_encoder
+                .begin_render_pass(&pass_descriptor);
+            let mut render_pass = TrackedRenderPass::new(render_pass);
+
+            if let Some(viewport) = camera.viewport.as_ref() {
+                render_pass.set_camera_viewport(viewport);
+            }
+
+            transparent_phase.render(&mut render_pass, world, view_entity);
         }
 
         // WebGL2 quirk: if ending with a render pass with a custom viewport, the viewport isn't

crates/bevy_pbr/src/render/light.rs

@@ -1785,13 +1785,12 @@ impl Node for ShadowPassNode {
                     }),
                 };
 
-                shadow_phase.render(
-                    world,
-                    render_context,
-                    view_light_entity,
-                    None,
-                    pass_descriptor,
-                );
+                let render_pass = render_context
+                    .command_encoder
+                    .begin_render_pass(&pass_descriptor);
+                let mut render_pass = TrackedRenderPass::new(render_pass);
+
+                shadow_phase.render(&mut render_pass, world, view_light_entity);
             }
         }
 

crates/bevy_render/src/render_phase/mod.rs

@@ -4,10 +4,7 @@ mod draw_state;
 use bevy_ecs::entity::Entity;
 pub use draw::*;
 pub use draw_state::*;
-use wgpu::RenderPassDescriptor;
 
-use crate::camera::Viewport;
-use crate::renderer::RenderContext;
 use bevy_ecs::prelude::{Component, Query};
 use bevy_ecs::world::World;
 
@@ -35,29 +32,18 @@ impl<I: PhaseItem> RenderPhase<I> {
         I::sort(&mut self.items);
     }
 
-    pub fn render(
+    pub fn render<'w>(
         &self,
-        world: &World,
-        render_context: &mut RenderContext,
+        render_pass: &mut TrackedRenderPass<'w>,
+        world: &'w World,
         view: Entity,
-        viewport: Option<&Viewport>,
-        pass_descriptor: RenderPassDescriptor,
     ) {
-        let render_pass = render_context
-            .command_encoder
-            .begin_render_pass(&pass_descriptor);
-        let mut render_pass = TrackedRenderPass::new(render_pass);
-
-        if let Some(viewport) = viewport {
-            render_pass.set_camera_viewport(viewport);
-        }
-
         let draw_functions = world.resource::<DrawFunctions<I>>();
         let mut draw_functions = draw_functions.write();
 
         for item in &self.items {
             let draw_function = draw_functions.get_mut(item.draw_function()).unwrap();
-            draw_function.draw(world, &mut render_pass, view, item);
+            draw_function.draw(world, render_pass, view, item);
         }
     }
 }

crates/bevy_ui/src/render/render_pass.rs

@@ -85,7 +85,13 @@ impl Node for UiPassNode {
             depth_stencil_attachment: None,
         };
 
-        transparent_phase.render(world, render_context, view_entity, None, pass_descriptor);
+        let render_pass = render_context
+            .command_encoder
+            .begin_render_pass(&pass_descriptor);
+        let mut render_pass = TrackedRenderPass::new(render_pass);
+
+        transparent_phase.render(&mut render_pass, world, view_entity);
+
         Ok(())
     }
 }