RenderResourceSet builder pattern

crates/bevy_render/src/draw.rs

@@ -9,7 +9,7 @@ use crate::{
 use bevy_asset::{Assets, Handle};
 use bevy_property::Properties;
 use legion::{
-    prelude::{Com, ComMut, Res},
+    prelude::{ComMut, Res},
     storage::Component,
 };
 use std::{ops::Range, sync::Arc};
@@ -146,17 +146,17 @@ impl<'a> DrawContext<'a> {
         self.draw.render_commands.push(render_command);
     }
 
-    pub fn draw<T: Drawable>(&mut self, drawable: &T) {
+    pub fn draw<T: Drawable>(&mut self, drawable: &mut T) {
         drawable.draw(self);
     }
 }
 
 pub trait Drawable {
-    fn draw(&self, draw: &mut DrawContext);
+    fn draw(&mut self, draw: &mut DrawContext);
 }
 
 impl Drawable for RenderPipelines {
-    fn draw(&self, draw: &mut DrawContext) {
+    fn draw(&mut self, draw: &mut DrawContext) {
         for pipeline_handle in self.compiled_pipelines.iter() {
             let pipeline = draw.pipelines.get(pipeline_handle).unwrap();
             let layout = pipeline.get_layout().unwrap();
@@ -209,11 +209,11 @@ pub fn draw_system<T: Drawable + Component>(
     render_resource_assignments: Res<RenderResourceAssignments>,
     render_resources: Res<RenderResources>,
     mut draw: ComMut<Draw>,
-    drawable: Com<T>,
+    mut drawable: ComMut<T>,
 ) {
     let context = &*render_resources.context;
     let mut draw_context = draw.get_context(&pipelines, context, &render_resource_assignments);
-    draw_context.draw(drawable.as_ref());
+    draw_context.draw(drawable.as_mut());
 }
 
 pub fn clear_draw_system(mut draw: ComMut<Draw>) {

crates/bevy_render/src/render_resource/mod.rs

@@ -1,6 +1,7 @@
 mod buffer;
 mod entities_waiting_for_assets;
 mod render_resource;
+mod render_resource_set;
 mod render_resource_assignments;
 mod resource_info;
 mod systems;
@@ -8,6 +9,7 @@ mod systems;
 pub use buffer::*;
 pub use entities_waiting_for_assets::*;
 pub use render_resource::*;
+pub use render_resource_set::*;
 pub use render_resource_assignments::*;
 pub use resource_info::*;
 pub use systems::*;

crates/bevy_render/src/render_resource/render_resource_assignments.rs

@@ -1,10 +1,9 @@
-use super::RenderResourceId;
+use super::{RenderResourceId, RenderResourceSet, RenderResourceSetId};
 use crate::pipeline::{BindGroupDescriptor, BindGroupDescriptorId, PipelineSpecialization};
 use std::{
-    collections::{hash_map::DefaultHasher, HashMap, HashSet},
+    collections::{HashMap, HashSet},
     hash::{Hash, Hasher},
     ops::Range,
-    sync::Arc,
 };
 use uuid::Uuid;
 
@@ -29,20 +28,6 @@ impl RenderResourceAssignment {
     }
 }
 
-#[derive(Eq, PartialEq, Debug)]
-pub struct IndexedRenderResourceAssignment {
-    pub index: u32,
-    pub assignment: RenderResourceAssignment,
-}
-
-// TODO: consider renaming this to BindGroup for parity with renderer terminology
-#[derive(Eq, PartialEq, Debug)]
-pub struct RenderResourceSet {
-    pub id: RenderResourceSetId,
-    pub indexed_assignments: Vec<IndexedRenderResourceAssignment>,
-    pub dynamic_uniform_indices: Option<Arc<Vec<u32>>>,
-}
-
 #[derive(Eq, PartialEq, Debug)]
 pub enum RenderResourceSetStatus {
     Changed(RenderResourceSetId),
@@ -103,7 +88,7 @@ impl RenderResourceAssignments {
         &mut self,
         bind_group_descriptor: &BindGroupDescriptor,
     ) -> RenderResourceSetStatus {
-        let resource_set = self.generate_render_resource_set(bind_group_descriptor);
+        let resource_set = self.build_render_resource_set(bind_group_descriptor);
         if let Some(resource_set) = resource_set {
             let id = resource_set.id;
             self.render_resource_sets.insert(id, resource_set);
@@ -149,42 +134,21 @@ impl RenderResourceAssignments {
             })
     }
 
-    fn generate_render_resource_set(
+    fn build_render_resource_set(
         &self,
         bind_group_descriptor: &BindGroupDescriptor,
     ) -> Option<RenderResourceSet> {
-        let mut hasher = DefaultHasher::new();
-        let mut indices = Vec::new();
-        let mut indexed_assignments = Vec::new();
+        let mut render_resource_set_builder = RenderResourceSet::build();
         for binding_descriptor in bind_group_descriptor.bindings.iter() {
             if let Some(assignment) = self.get(&binding_descriptor.name) {
-                indexed_assignments.push(IndexedRenderResourceAssignment {
-                    assignment: assignment.clone(),
-                    index: binding_descriptor.index,
-                });
-                let resource = assignment.get_resource();
-                resource.hash(&mut hasher);
-                if let RenderResourceAssignment::Buffer {
-                    dynamic_index: Some(index),
-                    ..
-                } = assignment
-                {
-                    indices.push(*index);
-                }
+                render_resource_set_builder = render_resource_set_builder
+                    .add_assignment(binding_descriptor.index, assignment.clone());
             } else {
                 return None;
             }
         }
 
-        Some(RenderResourceSet {
-            id: RenderResourceSetId(hasher.finish()),
-            indexed_assignments,
-            dynamic_uniform_indices: if indices.is_empty() {
-                None
-            } else {
-                Some(Arc::new(indices))
-            },
-        })
+        Some(render_resource_set_builder.finish())
     }
 }
 
@@ -197,9 +161,6 @@ impl Default for RenderResourceAssignmentsId {
     }
 }
 
-#[derive(Hash, Eq, PartialEq, Debug, Copy, Clone)]
-pub struct RenderResourceSetId(u64);
-
 #[cfg(test)]
 mod tests {
     use super::*;

crates/bevy_render/src/render_resource/render_resource_set.rs

@@ -0,0 +1,110 @@
+use super::{RenderResourceAssignment, RenderResourceId};
+use std::{
+    collections::hash_map::DefaultHasher,
+    hash::{Hash, Hasher},
+    ops::Range,
+    sync::Arc,
+};
+
+#[derive(Hash, Eq, PartialEq, Debug, Copy, Clone)]
+pub struct RenderResourceSetId(pub u64);
+
+#[derive(Eq, PartialEq, Debug)]
+pub struct IndexedRenderResourceAssignment {
+    pub index: u32,
+    pub assignment: RenderResourceAssignment,
+}
+
+// TODO: consider renaming this to BindGroup for parity with renderer terminology
+#[derive(Eq, PartialEq, Debug)]
+pub struct RenderResourceSet {
+    pub id: RenderResourceSetId,
+    pub indexed_assignments: Vec<IndexedRenderResourceAssignment>,
+    pub dynamic_uniform_indices: Option<Arc<Vec<u32>>>,
+}
+
+impl RenderResourceSet {
+    pub fn build() -> RenderResourceSetBuilder {
+        RenderResourceSetBuilder::default()
+    }
+}
+
+#[derive(Default)]
+pub struct RenderResourceSetBuilder {
+    pub indexed_assignments: Vec<IndexedRenderResourceAssignment>,
+    pub dynamic_uniform_indices: Vec<u32>,
+    pub hasher: DefaultHasher,
+}
+
+impl RenderResourceSetBuilder {
+    pub fn add_assignment(mut self, index: u32, assignment: RenderResourceAssignment) -> Self {
+        if let RenderResourceAssignment::Buffer {
+            dynamic_index: Some(dynamic_index),
+            ..
+        } = assignment
+        {
+            self.dynamic_uniform_indices.push(dynamic_index);
+        }
+
+        let resource = assignment.get_resource();
+        resource.hash(&mut self.hasher);
+        self.indexed_assignments
+            .push(IndexedRenderResourceAssignment { index, assignment });
+        self
+    }
+
+    pub fn add_texture(self, index: u32, render_resource: RenderResourceId) -> Self {
+        self.add_assignment(index, RenderResourceAssignment::Texture(render_resource))
+    }
+
+    pub fn add_sampler(self, index: u32, render_resource: RenderResourceId) -> Self {
+        self.add_assignment(index, RenderResourceAssignment::Sampler(render_resource))
+    }
+
+    pub fn add_buffer(
+        self,
+        index: u32,
+        render_resource: RenderResourceId,
+        range: Range<u64>,
+    ) -> Self {
+        self.add_assignment(
+            index,
+            RenderResourceAssignment::Buffer {
+                resource: render_resource,
+                range,
+                dynamic_index: None,
+            },
+        )
+    }
+
+    pub fn add_dynamic_buffer(
+        self,
+        index: u32,
+        render_resource: RenderResourceId,
+        range: Range<u64>,
+        dynamic_index: u32,
+    ) -> Self {
+        self.add_assignment(
+            index,
+            RenderResourceAssignment::Buffer {
+                resource: render_resource,
+                range,
+                dynamic_index: Some(dynamic_index),
+            },
+        )
+    }
+
+    pub fn finish(mut self) -> RenderResourceSet {
+        // this sort ensures that RenderResourceSets are insertion-order independent
+        self.indexed_assignments.sort_by_key(|i| i.index);
+        RenderResourceSet {
+            id: RenderResourceSetId(self.hasher.finish()),
+            indexed_assignments: self.indexed_assignments,
+            dynamic_uniform_indices: if self.dynamic_uniform_indices.is_empty() {
+                None
+            } else {
+                Some(Arc::new(self.dynamic_uniform_indices))
+            },
+        }
+    }
+}