Optimize Text rendering / SharedBuffers

crates/bevy_render/src/draw.rs

@@ -1,7 +1,7 @@
 use crate::{
     pipeline::{PipelineCompiler, PipelineDescriptor, PipelineLayout, PipelineSpecialization},
     renderer::{
-        BindGroup, BindGroupId, BufferId, BufferUsage, RenderResource, RenderResourceBinding,
+        BindGroup, BindGroupId, BufferId, RenderResource, RenderResourceBinding,
         RenderResourceBindings, RenderResourceContext, SharedBuffers,
     },
     shader::Shader,
@@ -125,7 +125,7 @@ pub struct DrawContext<'a> {
     pub shaders: ResMut<'a, Assets<Shader>>,
     pub pipeline_compiler: ResMut<'a, PipelineCompiler>,
     pub render_resource_context: Res<'a, Box<dyn RenderResourceContext>>,
-    pub shared_buffers: Res<'a, SharedBuffers>,
+    pub shared_buffers: ResMut<'a, SharedBuffers>,
     #[system_param(ignore)]
     pub current_pipeline: Option<Handle<PipelineDescriptor>>,
 }
@@ -135,19 +135,11 @@ pub struct FetchDrawContext;
 
 impl<'a> DrawContext<'a> {
     pub fn get_uniform_buffer<T: RenderResource>(
-        &self,
-        render_resource: &T,
-    ) -> Result<RenderResourceBinding, DrawError> {
-        self.get_buffer(render_resource, BufferUsage::UNIFORM)
-    }
-
-    pub fn get_buffer<T: RenderResource>(
-        &self,
+        &mut self,
         render_resource: &T,
-        buffer_usage: BufferUsage,
     ) -> Result<RenderResourceBinding, DrawError> {
         self.shared_buffers
-            .get_buffer(render_resource, buffer_usage)
+            .get_uniform_buffer(&**self.render_resource_context, render_resource)
             .ok_or(DrawError::BufferAllocationFailure)
     }
 

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

@@ -16,8 +16,7 @@ impl Node for SharedBuffersNode {
         _input: &ResourceSlots,
         _output: &mut ResourceSlots,
     ) {
-        let shared_buffers = resources.get::<SharedBuffers>().unwrap();
-        let mut command_queue = shared_buffers.reset_command_queue();
-        command_queue.execute(render_context);
+        let mut shared_buffers = resources.get_mut::<SharedBuffers>().unwrap();
+        shared_buffers.apply(render_context);
     }
 }

crates/bevy_render/src/renderer/render_resource/shared_buffers.rs

@@ -1,99 +1,136 @@
 use super::{BufferId, BufferInfo, RenderResource, RenderResourceBinding};
 use crate::{
     render_graph::CommandQueue,
-    renderer::{BufferUsage, RenderResourceContext},
+    renderer::{BufferUsage, RenderContext, RenderResourceContext},
 };
-use bevy_ecs::Res;
-use parking_lot::RwLock;
-use std::sync::Arc;
+use bevy_ecs::{Res, ResMut};
 
-// TODO: Instead of allocating small "exact size" buffers each frame, this should use multiple large shared buffers and probably
-// a long-living "cpu mapped" staging buffer. Im punting that for now because I don't know the best way to use wgpu's new async
-// buffer mapping yet.
 pub struct SharedBuffers {
-    render_resource_context: Box<dyn RenderResourceContext>,
-    buffers: Arc<RwLock<Vec<BufferId>>>,
-    command_queue: Arc<RwLock<CommandQueue>>,
+    staging_buffer: Option<BufferId>,
+    uniform_buffer: Option<BufferId>,
+    buffers_to_free: Vec<BufferId>,
+    buffer_size: usize,
+    initial_size: usize,
+    current_offset: usize,
+    command_queue: CommandQueue,
 }
 
 impl SharedBuffers {
-    pub fn new(render_resource_context: Box<dyn RenderResourceContext>) -> Self {
+    pub fn new(initial_size: usize) -> Self {
         Self {
-            render_resource_context,
-            buffers: Default::default(),
+            staging_buffer: None,
+            uniform_buffer: None,
+            buffer_size: 0,
+            current_offset: 0,
+            initial_size,
+            buffers_to_free: Default::default(),
             command_queue: Default::default(),
         }
     }
 
-    pub fn get_buffer<T: RenderResource>(
-        &self,
+    pub fn grow(
+        &mut self,
+        render_resource_context: &dyn RenderResourceContext,
+        required_space: usize,
+    ) {
+        while self.buffer_size < self.current_offset + required_space {
+            self.buffer_size = if self.buffer_size == 0 {
+                self.initial_size
+            } else {
+                self.buffer_size * 2
+            };
+        }
+
+        self.current_offset = 0;
+
+        if let Some(staging_buffer) = self.staging_buffer.take() {
+            render_resource_context.unmap_buffer(staging_buffer);
+            self.buffers_to_free.push(staging_buffer);
+        }
+
+        if let Some(uniform_buffer) = self.uniform_buffer.take() {
+            self.buffers_to_free.push(uniform_buffer);
+        }
+
+        self.staging_buffer = Some(render_resource_context.create_buffer(BufferInfo {
+            size: self.buffer_size,
+            buffer_usage: BufferUsage::MAP_WRITE | BufferUsage::COPY_SRC,
+            mapped_at_creation: true,
+        }));
+        self.uniform_buffer = Some(render_resource_context.create_buffer(BufferInfo {
+            size: self.buffer_size,
+            buffer_usage: BufferUsage::COPY_DST | BufferUsage::UNIFORM,
+            mapped_at_creation: false,
+        }));
+    }
+
+    pub fn get_uniform_buffer<T: RenderResource>(
+        &mut self,
+        render_resource_context: &dyn RenderResourceContext,
         render_resource: &T,
-        buffer_usage: BufferUsage,
     ) -> Option<RenderResourceBinding> {
         if let Some(size) = render_resource.buffer_byte_len() {
-            let aligned_size = self
-                .render_resource_context
-                .get_aligned_uniform_size(size, false);
-            // PERF: this buffer will be slow
-            let staging_buffer = self.render_resource_context.create_buffer(BufferInfo {
-                size: aligned_size,
-                buffer_usage: BufferUsage::COPY_SRC | BufferUsage::MAP_WRITE,
-                mapped_at_creation: true,
-            });
+            // TODO: overlap alignment if/when possible
+            let aligned_size = render_resource_context.get_aligned_uniform_size(size, true);
+            let mut new_offset = self.current_offset + aligned_size;
+            if new_offset > self.buffer_size {
+                self.grow(render_resource_context, aligned_size);
+                new_offset = aligned_size;
+            }
 
-            self.render_resource_context.write_mapped_buffer(
+            let range = self.current_offset as u64..new_offset as u64;
+            let staging_buffer = self.staging_buffer.unwrap();
+            let uniform_buffer = self.uniform_buffer.unwrap();
+            render_resource_context.write_mapped_buffer(
                 staging_buffer,
-                0..size as u64,
+                range.clone(),
                 &mut |data, _renderer| {
                     render_resource.write_buffer_bytes(data);
                 },
             );
 
-            self.render_resource_context.unmap_buffer(staging_buffer);
-
-            let destination_buffer = self.render_resource_context.create_buffer(BufferInfo {
-                size: aligned_size,
-                buffer_usage: BufferUsage::COPY_DST | buffer_usage,
-                ..Default::default()
-            });
-
-            let mut command_queue = self.command_queue.write();
-            command_queue.copy_buffer_to_buffer(
+            self.command_queue.copy_buffer_to_buffer(
                 staging_buffer,
-                0,
-                destination_buffer,
-                0,
-                size as u64,
+                self.current_offset as u64,
+                uniform_buffer,
+                self.current_offset as u64,
+                aligned_size as u64,
             );
 
-            let mut buffers = self.buffers.write();
-            buffers.push(staging_buffer);
-            buffers.push(destination_buffer);
+            self.current_offset = new_offset;
             Some(RenderResourceBinding::Buffer {
-                buffer: destination_buffer,
-                range: 0..aligned_size as u64,
+                buffer: uniform_buffer,
+                range,
                 dynamic_index: None,
             })
         } else {
             None
         }
     }
 
-    // TODO: remove this when this actually uses shared buffers
-    pub fn free_buffers(&self) {
-        let mut buffers = self.buffers.write();
-        for buffer in buffers.drain(..) {
-            self.render_resource_context.remove_buffer(buffer)
+    pub fn update(&mut self, render_resource_context: &dyn RenderResourceContext) {
+        self.current_offset = 0;
+        for buffer in self.buffers_to_free.drain(..) {
+            render_resource_context.remove_buffer(buffer)
+        }
+
+        if let Some(staging_buffer) = self.staging_buffer {
+            render_resource_context.map_buffer(staging_buffer);
         }
     }
 
-    pub fn reset_command_queue(&self) -> CommandQueue {
-        let mut command_queue = self.command_queue.write();
-        std::mem::take(&mut *command_queue)
+    pub fn apply(&mut self, render_context: &mut dyn RenderContext) {
+        if let Some(staging_buffer) = self.staging_buffer {
+            render_context.resources().unmap_buffer(staging_buffer);
+        }
+        let mut command_queue = std::mem::take(&mut self.command_queue);
+        command_queue.execute(render_context);
     }
 }
 
-// TODO: remove this when this actually uses shared buffers
-pub fn free_shared_buffers_system(shared_buffers: Res<SharedBuffers>) {
-    shared_buffers.free_buffers();
+pub fn shared_buffers_update_system(
+    mut shared_buffers: ResMut<SharedBuffers>,
+    render_resource_context: Res<Box<dyn RenderResourceContext>>,
+) {
+    shared_buffers.update(&**render_resource_context);
 }

crates/bevy_text/src/draw.rs

@@ -5,10 +5,7 @@ use bevy_render::{
     mesh,
     pipeline::{PipelineSpecialization, VertexBufferDescriptor},
     prelude::Msaa,
-    renderer::{
-        AssetRenderResourceBindings, BindGroup, BufferUsage, RenderResourceBindings,
-        RenderResourceId,
-    },
+    renderer::{AssetRenderResourceBindings, BindGroup, RenderResourceBindings, RenderResourceId},
 };
 use bevy_sprite::TextureAtlasSprite;
 use glyph_brush_layout::{HorizontalAlign, VerticalAlign};
@@ -108,14 +105,8 @@ impl<'a> Drawable for DrawableText<'a> {
 
             let transform = Mat4::from_translation(self.position + tv.position.extend(0.));
 
-            let transform_buffer = context
-                .shared_buffers
-                .get_buffer(&transform, BufferUsage::UNIFORM)
-                .unwrap();
-            let sprite_buffer = context
-                .shared_buffers
-                .get_buffer(&sprite, BufferUsage::UNIFORM)
-                .unwrap();
+            let transform_buffer = context.get_uniform_buffer(&transform).unwrap();
+            let sprite_buffer = context.get_uniform_buffer(&sprite).unwrap();
             let sprite_bind_group = BindGroup::build()
                 .add_binding(0, transform_buffer)
                 .add_binding(1, sprite_buffer)

crates/bevy_wgpu/src/lib.rs

@@ -12,7 +12,7 @@ pub use wgpu_resources::*;
 
 use bevy_app::prelude::*;
 use bevy_ecs::{Resources, World};
-use bevy_render::renderer::{free_shared_buffers_system, RenderResourceContext, SharedBuffers};
+use bevy_render::renderer::{shared_buffers_update_system, RenderResourceContext, SharedBuffers};
 use renderer::WgpuRenderResourceContext;
 
 #[derive(Default)]
@@ -22,7 +22,10 @@ impl Plugin for WgpuPlugin {
     fn build(&self, app: &mut AppBuilder) {
         let render_system = get_wgpu_render_system(app.resources_mut());
         app.add_system_to_stage(bevy_render::stage::RENDER, render_system)
-            .add_system_to_stage(bevy_render::stage::POST_RENDER, free_shared_buffers_system);
+            .add_system_to_stage(
+                bevy_render::stage::POST_RENDER,
+                shared_buffers_update_system,
+            );
     }
 }
 
@@ -32,8 +35,8 @@ pub fn get_wgpu_render_system(resources: &mut Resources) -> impl FnMut(&mut Worl
         .unwrap_or_else(WgpuOptions::default);
     let mut wgpu_renderer = future::block_on(WgpuRenderer::new(options));
     let resource_context = WgpuRenderResourceContext::new(wgpu_renderer.device.clone());
-    resources.insert::<Box<dyn RenderResourceContext>>(Box::new(resource_context.clone()));
-    resources.insert(SharedBuffers::new(Box::new(resource_context)));
+    resources.insert::<Box<dyn RenderResourceContext>>(Box::new(resource_context));
+    resources.insert(SharedBuffers::new(4096));
     move |world, resources| {
         wgpu_renderer.update(world, resources);
     }