Adds GlobalRenderResourcesNode to easily bind Resources

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

@@ -19,7 +19,7 @@ use bevy_ecs::{
 };
 use bevy_utils::HashMap;
 use renderer::{AssetRenderResourceBindings, BufferId, RenderResourceType, RenderResources};
-use std::{any::TypeId, hash::Hash, marker::PhantomData, ops::DerefMut};
+use std::{any::TypeId, hash::Hash, io::Write, marker::PhantomData, ops::DerefMut};
 
 #[derive(Debug)]
 struct QueuedBufferWrite {
@@ -808,3 +808,195 @@ where
 
     success
 }
+
+#[derive(Debug, Default)]
+pub struct GlobalRenderResourcesNode<T>
+where
+    T: RenderResources,
+{
+    command_queue: CommandQueue,
+    marker: PhantomData<T>,
+}
+
+impl<T> GlobalRenderResourcesNode<T>
+where
+    T: RenderResources,
+{
+    pub fn new() -> Self {
+        Self {
+            command_queue: CommandQueue::default(),
+            marker: Default::default(),
+        }
+    }
+}
+
+impl<T> Node for GlobalRenderResourcesNode<T>
+where
+    T: RenderResources,
+{
+    fn update(
+        &mut self,
+        _world: &World,
+        render_context: &mut dyn RenderContext,
+        _input: &ResourceSlots,
+        _output: &mut ResourceSlots,
+    ) {
+        // dbg!();
+        self.command_queue.execute(render_context);
+    }
+}
+
+impl<T> SystemNode for GlobalRenderResourcesNode<T>
+where
+    T: renderer::RenderResources,
+{
+    fn get_system(&self) -> BoxedSystem {
+        let system = global_render_resources_node_system::<T>
+            .system()
+            .config(|config| {
+                config.0 = Some(GlobalRenderResourcesNodeState {
+                    command_queue: self.command_queue.clone(),
+                    ..Default::default()
+                })
+            });
+
+        Box::new(system)
+    }
+}
+
+struct GlobalRenderResourcesNodeState<T: RenderResources> {
+    command_queue: CommandQueue,
+    staging_buffer: Option<BufferId>,
+    target_buffer: Option<BufferId>,
+    _marker: PhantomData<T>,
+}
+
+impl<T: RenderResources> Default for GlobalRenderResourcesNodeState<T> {
+    fn default() -> Self {
+        Self {
+            command_queue: Default::default(),
+            staging_buffer: None,
+            target_buffer: None,
+            _marker: Default::default(),
+        }
+    }
+}
+
+fn global_render_resources_node_system<T: RenderResources>(
+    mut state: Local<GlobalRenderResourcesNodeState<T>>,
+    render_resources: Res<T>,
+    render_resource_context: Res<Box<dyn RenderResourceContext>>,
+    mut render_resource_bindings: ResMut<RenderResourceBindings>,
+) {
+    // TODO add support for textures
+    // No need to do anything if no changes
+    if render_resources.is_changed() {
+        // Precalculate the aligned size of the whole render resources buffer
+        let aligned_size = render_resources
+            .iter()
+            .fold(0, |aligned_size, render_resource| {
+                aligned_size
+                    + render_resource_context
+                        .get_aligned_uniform_size(render_resource.buffer_byte_len().unwrap(), false)
+            });
+
+        // Get old buffer and possibly resize
+        let staging_buffer = match state.staging_buffer {
+            Some(staging_buffer) => {
+                if render_resource_context
+                    .get_buffer_info(staging_buffer)
+                    .unwrap()
+                    .size
+                    != aligned_size
+                {
+                    render_resource_context.remove_buffer(staging_buffer);
+                    render_resource_context.create_buffer(BufferInfo {
+                        size: aligned_size,
+                        buffer_usage: BufferUsage::COPY_SRC | BufferUsage::MAP_WRITE,
+                        mapped_at_creation: true,
+                    })
+                } else {
+                    staging_buffer
+                }
+            }
+            None => {
+                // Or create a new one
+                render_resource_context.create_buffer(BufferInfo {
+                    size: aligned_size,
+                    buffer_usage: BufferUsage::COPY_SRC | BufferUsage::MAP_WRITE,
+                    mapped_at_creation: true,
+                })
+            }
+        };
+
+        // Get old buffer and possibly resize
+        let target_buffer = if let Some(target_buffer) = state.target_buffer {
+            if render_resource_context
+                .get_buffer_info(target_buffer)
+                .unwrap()
+                .size
+                != aligned_size
+            {
+                render_resource_context.remove_buffer(target_buffer);
+                render_resource_context.create_buffer(BufferInfo {
+                    size: aligned_size,
+                    buffer_usage: BufferUsage::COPY_DST | BufferUsage::UNIFORM,
+                    mapped_at_creation: false,
+                })
+            } else {
+                target_buffer
+            }
+        } else {
+            // Or create a new one
+            render_resource_context.create_buffer(BufferInfo {
+                size: aligned_size,
+                buffer_usage: BufferUsage::COPY_DST | BufferUsage::UNIFORM,
+                mapped_at_creation: false,
+            })
+        };
+
+        // Write the resources into the staging buffer
+        let mut offset = 0u64;
+        for (index, render_resource) in render_resources.iter().enumerate() {
+            let render_resource_name = render_resources.get_render_resource_name(index).unwrap();
+            // dbg!(&render_resource_name);
+
+            let size = render_resource.buffer_byte_len().unwrap();
+            let aligned_size = render_resource_context.get_aligned_uniform_size(size, false) as u64;
+
+            render_resource_context.write_mapped_buffer(
+                staging_buffer,
+                offset..(offset + aligned_size),
+                &mut |mut buf, _render_resource_context| {
+                    render_resource.write_buffer_bytes(buf);
+
+                    // add padding
+                    for _ in 0..(aligned_size - size as u64) {
+                        buf.write_all(&[0]).unwrap();
+                    }
+                },
+            );
+
+            render_resource_bindings.set(
+                render_resource_name,
+                RenderResourceBinding::Buffer {
+                    buffer: target_buffer,
+                    range: offset..(offset + aligned_size),
+                    dynamic_index: None,
+                },
+            );
+
+            offset += aligned_size;
+        }
+
+        render_resource_context.unmap_buffer(staging_buffer);
+
+        state.command_queue.copy_buffer_to_buffer(
+            staging_buffer,
+            0,
+            target_buffer,
+            0,
+            aligned_size as u64,
+        );
+    }
+}