a lot of new buffers created all the time after #599

[mrk-its]

Bevy version
current master (4645da3 or later)

Operating system & version
Ubuntu 20.04

What you did

Apply this patch to print a line on stdout when new buffer is created:

diff --git a/crates/bevy_wgpu/src/renderer/wgpu_render_resource_context.rs b/crates/bevy_wgpu/src/renderer/wgpu_render_resource_context.rs
index ab5048da..2e3df8e6 100644
--- a/crates/bevy_wgpu/src/renderer/wgpu_render_resource_context.rs
+++ b/crates/bevy_wgpu/src/renderer/wgpu_render_resource_context.rs
@@ -185,6 +185,7 @@ impl RenderResourceContext for WgpuRenderResourceContext {
     }
 
     fn create_buffer(&self, buffer_info: BufferInfo) -> BufferId {
+        println!("create_buffer");
         // TODO: consider moving this below "create" for efficiency
         let mut buffer_infos = self.resources.buffer_infos.write();
         let mut buffers = self.resources.buffers.write();
@@ -203,6 +204,7 @@ impl RenderResourceContext for WgpuRenderResourceContext {
     }
 
     fn create_buffer_with_data(&self, mut buffer_info: BufferInfo, data: &[u8]) -> BufferId {
+        println!("create_buffer_with_data");
         // TODO: consider moving this below "create" for efficiency
         let mut buffer_infos = self.resources.buffer_infos.write();
         let mut buffers = self.resources.buffers.write();

and run

cargo run --example sprite

What you expected to happen

there should be constant number of buffers allocated

What actually happened

New buffers are created all the time (for sprite example it is like ~3 new buffers per frame)

Additional information

This behavior was introduced in #599 (4645da3)

[mrk-its]

@julhe could you take a look?

[julhe]

Okay, this seems because I made this a ResMut<>

bevy/crates/bevy_render/src/mesh/mesh.rs

Line 459 in f81208a

mut meshes: ResMut<Assets<Mesh>>,

This causes

bevy/crates/bevy_render/src/mesh/mesh.rs

Lines 470 to 473 in f81208a

	AssetEvent::Modified { ref handle } => {
	changed_meshes.insert(handle.clone_weak());
	remove_current_mesh_resources(render_resource_context, handle);
	}

to be triggered every frame, finally leading to the constant buffer recreation.

Problem is that I need to have the Mesh mutable, to set

bevy/crates/bevy_render/src/mesh/mesh.rs

Line 506 in f81208a

mesh.attribute_buffer_descriptor_reference = Some(interleaved_buffer.1);

So the only option I see is to store attribute_buffer_descriptor_reference outside of Mesh, so we can go back to Res<>.

But where? 🤔