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//! The modular rendering abstraction responsible for queuing, preparing, sorting and drawing
//! entities as part of separate render phases.
//!
//! In Bevy each view (camera, or shadow-casting light, etc.) has one or multiple render phases
//! (e.g. opaque, transparent, shadow, etc).
//! They are used to queue entities for rendering.
//! Multiple phases might be required due to different sorting/batching behaviors
//! (e.g. opaque: front to back, transparent: back to front) or because one phase depends on
//! the rendered texture of the previous phase (e.g. for screen-space reflections).
//!
//! To draw an entity, a corresponding [`PhaseItem`] has to be added to one or multiple of these
//! render phases for each view that it is visible in.
//! This must be done in the [`RenderSet::Queue`].
//! After that the render phase sorts them in the [`RenderSet::PhaseSort`].
//! Finally the items are rendered using a single [`TrackedRenderPass`], during
//! the [`RenderSet::Render`].
//!
//! Therefore each phase item is assigned a [`Draw`] function.
//! These set up the state of the [`TrackedRenderPass`] (i.e. select the
//! [`RenderPipeline`](crate::render_resource::RenderPipeline), configure the
//! [`BindGroup`](crate::render_resource::BindGroup)s, etc.) and then issue a draw call,
//! for the corresponding item.
//!
//! The [`Draw`] function trait can either be implemented directly or such a function can be
//! created by composing multiple [`RenderCommand`]s.
mod draw;
mod draw_state;
mod rangefinder;
use bevy_app::{App, Plugin};
use bevy_derive::{Deref, DerefMut};
use bevy_utils::{default, hashbrown::hash_map::Entry, HashMap};
pub use draw::*;
pub use draw_state::*;
use encase::{internal::WriteInto, ShaderSize};
use nonmax::NonMaxU32;
pub use rangefinder::*;
use crate::{
batching::{
self,
gpu_preprocessing::{self, BatchedInstanceBuffers},
no_gpu_preprocessing::{self, BatchedInstanceBuffer},
GetFullBatchData,
},
render_resource::{CachedRenderPipelineId, GpuArrayBufferIndex, PipelineCache},
Render, RenderApp, RenderSet,
};
use bevy_ecs::{
entity::EntityHashMap,
prelude::*,
system::{lifetimeless::SRes, SystemParamItem},
};
use smallvec::SmallVec;
use std::{
fmt::{self, Debug, Formatter},
hash::Hash,
iter,
marker::PhantomData,
ops::Range,
slice::SliceIndex,
};
/// Stores the rendering instructions for a single phase that uses bins in all
/// views.
///
/// They're cleared out every frame, but storing them in a resource like this
/// allows us to reuse allocations.
#[derive(Resource, Deref, DerefMut)]
pub struct ViewBinnedRenderPhases<BPI>(pub EntityHashMap<BinnedRenderPhase<BPI>>)
where
BPI: BinnedPhaseItem;
/// A collection of all rendering instructions, that will be executed by the GPU, for a
/// single render phase for a single view.
///
/// Each view (camera, or shadow-casting light, etc.) can have one or multiple render phases.
/// They are used to queue entities for rendering.
/// Multiple phases might be required due to different sorting/batching behaviors
/// (e.g. opaque: front to back, transparent: back to front) or because one phase depends on
/// the rendered texture of the previous phase (e.g. for screen-space reflections).
/// All [`PhaseItem`]s are then rendered using a single [`TrackedRenderPass`].
/// The render pass might be reused for multiple phases to reduce GPU overhead.
///
/// This flavor of render phase is used for phases in which the ordering is less
/// critical: for example, `Opaque3d`. It's generally faster than the
/// alternative [`SortedRenderPhase`].
pub struct BinnedRenderPhase<BPI>
where
BPI: BinnedPhaseItem,
{
/// A list of `BinKey`s for batchable items.
///
/// These are accumulated in `queue_material_meshes` and then sorted in
/// `batch_and_prepare_binned_render_phase`.
pub batchable_mesh_keys: Vec<BPI::BinKey>,
/// The batchable bins themselves.
///
/// Each bin corresponds to a single batch set. For unbatchable entities,
/// prefer `unbatchable_values` instead.
pub(crate) batchable_mesh_values: HashMap<BPI::BinKey, Vec<Entity>>,
/// A list of `BinKey`s for unbatchable items.
///
/// These are accumulated in `queue_material_meshes` and then sorted in
/// `batch_and_prepare_binned_render_phase`.
pub unbatchable_mesh_keys: Vec<BPI::BinKey>,
/// The unbatchable bins.
///
/// Each entity here is rendered in a separate drawcall.
pub(crate) unbatchable_mesh_values: HashMap<BPI::BinKey, UnbatchableBinnedEntities>,
/// Items in the bin that aren't meshes at all.
///
/// Bevy itself doesn't place anything in this list, but plugins or your app
/// can in order to execute custom drawing commands. Draw functions for each
/// entity are simply called in order at rendering time.
///
/// See the `custom_phase_item` example for an example of how to use this.
pub non_mesh_items: Vec<(BPI::BinKey, Entity)>,
/// Information on each batch set.
///
/// A *batch set* is a set of entities that will be batched together unless
/// we're on a platform that doesn't support storage buffers (e.g. WebGL 2)
/// and differing dynamic uniform indices force us to break batches. On
/// platforms that support storage buffers, a batch set always consists of
/// at most one batch.
///
/// The unbatchable entities immediately follow the batches in the storage
/// buffers.
pub(crate) batch_sets: Vec<SmallVec<[BinnedRenderPhaseBatch; 1]>>,
}
/// Information about a single batch of entities rendered using binned phase
/// items.
#[derive(Debug)]
pub struct BinnedRenderPhaseBatch {
/// An entity that's *representative* of this batch.
///
/// Bevy uses this to fetch the mesh. It can be any entity in the batch.
pub representative_entity: Entity,
/// The range of instance indices in this batch.
pub instance_range: Range<u32>,
/// The dynamic offset of the batch.
///
/// Note that dynamic offsets are only used on platforms that don't support
/// storage buffers.
pub extra_index: PhaseItemExtraIndex,
}
/// Information about the unbatchable entities in a bin.
pub(crate) struct UnbatchableBinnedEntities {
/// The entities.
pub(crate) entities: Vec<Entity>,
/// The GPU array buffer indices of each unbatchable binned entity.
pub(crate) buffer_indices: UnbatchableBinnedEntityIndexSet,
}
/// Stores instance indices and dynamic offsets for unbatchable entities in a
/// binned render phase.
///
/// This is conceptually `Vec<UnbatchableBinnedEntityDynamicOffset>`, but it
/// avoids the overhead of storing dynamic offsets on platforms that support
/// them. In other words, this allows a fast path that avoids allocation on
/// platforms that aren't WebGL 2.
#[derive(Default)]
pub(crate) enum UnbatchableBinnedEntityIndexSet {
/// There are no unbatchable entities in this bin (yet).
#[default]
NoEntities,
/// The instances for all unbatchable entities in this bin are contiguous,
/// and there are no dynamic uniforms.
///
/// This is the typical case on platforms other than WebGL 2. We special
/// case this to avoid allocation on those platforms.
Sparse {
/// The range of indices.
instance_range: Range<u32>,
/// The index of the first indirect instance parameters.
///
/// The other indices immediately follow these.
first_indirect_parameters_index: Option<NonMaxU32>,
},
/// Dynamic uniforms are present for unbatchable entities in this bin.
///
/// We fall back to this on WebGL 2.
Dense(Vec<UnbatchableBinnedEntityIndices>),
}
/// The instance index and dynamic offset (if present) for an unbatchable entity.
///
/// This is only useful on platforms that don't support storage buffers.
#[derive(Clone, Copy)]
pub(crate) struct UnbatchableBinnedEntityIndices {
/// The instance index.
pub(crate) instance_index: u32,
/// The [`PhaseItemExtraIndex`], if present.
pub(crate) extra_index: PhaseItemExtraIndex,
}
/// Identifies the list within [`BinnedRenderPhase`] that a phase item is to be
/// placed in.
#[derive(Clone, Copy, PartialEq, Debug)]
pub enum BinnedRenderPhaseType {
/// The item is a mesh that's eligible for indirect rendering and can be
/// batched with other meshes of the same type.
BatchableMesh,
/// The item is a mesh that's eligible for indirect rendering, but can't be
/// batched with other meshes of the same type.
///
/// At the moment, this is used for skinned meshes.
UnbatchableMesh,
/// The item isn't a mesh at all.
///
/// Bevy will simply invoke the drawing commands for such items one after
/// another, with no further processing.
///
/// The engine itself doesn't enqueue any items of this type, but it's
/// available for use in your application and/or plugins.
NonMesh,
}
impl<T> From<GpuArrayBufferIndex<T>> for UnbatchableBinnedEntityIndices
where
T: Clone + ShaderSize + WriteInto,
{
fn from(value: GpuArrayBufferIndex<T>) -> Self {
UnbatchableBinnedEntityIndices {
instance_index: value.index,
extra_index: PhaseItemExtraIndex::maybe_dynamic_offset(value.dynamic_offset),
}
}
}
impl<BPI> Default for ViewBinnedRenderPhases<BPI>
where
BPI: BinnedPhaseItem,
{
fn default() -> Self {
Self(default())
}
}
impl<BPI> ViewBinnedRenderPhases<BPI>
where
BPI: BinnedPhaseItem,
{
pub fn insert_or_clear(&mut self, entity: Entity) {
match self.entry(entity) {
Entry::Occupied(mut entry) => entry.get_mut().clear(),
Entry::Vacant(entry) => {
entry.insert(default());
}
}
}
}
impl<BPI> BinnedRenderPhase<BPI>
where
BPI: BinnedPhaseItem,
{
/// Bins a new entity.
///
/// The `phase_type` parameter specifies whether the entity is a
/// preprocessable mesh and whether it can be binned with meshes of the same
/// type.
pub fn add(&mut self, key: BPI::BinKey, entity: Entity, phase_type: BinnedRenderPhaseType) {
match phase_type {
BinnedRenderPhaseType::BatchableMesh => {
match self.batchable_mesh_values.entry(key.clone()) {
Entry::Occupied(mut entry) => entry.get_mut().push(entity),
Entry::Vacant(entry) => {
self.batchable_mesh_keys.push(key);
entry.insert(vec![entity]);
}
}
}
BinnedRenderPhaseType::UnbatchableMesh => {
match self.unbatchable_mesh_values.entry(key.clone()) {
Entry::Occupied(mut entry) => entry.get_mut().entities.push(entity),
Entry::Vacant(entry) => {
self.unbatchable_mesh_keys.push(key);
entry.insert(UnbatchableBinnedEntities {
entities: vec![entity],
buffer_indices: default(),
});
}
}
}
BinnedRenderPhaseType::NonMesh => {
// We don't process these items further.
self.non_mesh_items.push((key, entity));
}
}
}
/// Encodes the GPU commands needed to render all entities in this phase.
pub fn render<'w>(
&self,
render_pass: &mut TrackedRenderPass<'w>,
world: &'w World,
view: Entity,
) {
{
let draw_functions = world.resource::<DrawFunctions<BPI>>();
let mut draw_functions = draw_functions.write();
draw_functions.prepare(world);
// Make sure to drop the reader-writer lock here to avoid recursive
// locks.
}
self.render_batchable_meshes(render_pass, world, view);
self.render_unbatchable_meshes(render_pass, world, view);
self.render_non_meshes(render_pass, world, view);
}
/// Renders all batchable meshes queued in this phase.
fn render_batchable_meshes<'w>(
&self,
render_pass: &mut TrackedRenderPass<'w>,
world: &'w World,
view: Entity,
) {
let draw_functions = world.resource::<DrawFunctions<BPI>>();
let mut draw_functions = draw_functions.write();
debug_assert_eq!(self.batchable_mesh_keys.len(), self.batch_sets.len());
for (key, batch_set) in self.batchable_mesh_keys.iter().zip(self.batch_sets.iter()) {
for batch in batch_set {
let binned_phase_item = BPI::new(
key.clone(),
batch.representative_entity,
batch.instance_range.clone(),
batch.extra_index,
);
// Fetch the draw function.
let Some(draw_function) = draw_functions.get_mut(binned_phase_item.draw_function())
else {
continue;
};
draw_function.draw(world, render_pass, view, &binned_phase_item);
}
}
}
/// Renders all unbatchable meshes queued in this phase.
fn render_unbatchable_meshes<'w>(
&self,
render_pass: &mut TrackedRenderPass<'w>,
world: &'w World,
view: Entity,
) {
let draw_functions = world.resource::<DrawFunctions<BPI>>();
let mut draw_functions = draw_functions.write();
for key in &self.unbatchable_mesh_keys {
let unbatchable_entities = &self.unbatchable_mesh_values[key];
for (entity_index, &entity) in unbatchable_entities.entities.iter().enumerate() {
let unbatchable_dynamic_offset = match &unbatchable_entities.buffer_indices {
UnbatchableBinnedEntityIndexSet::NoEntities => {
// Shouldn't happen…
continue;
}
UnbatchableBinnedEntityIndexSet::Sparse {
instance_range,
first_indirect_parameters_index,
} => UnbatchableBinnedEntityIndices {
instance_index: instance_range.start + entity_index as u32,
extra_index: match first_indirect_parameters_index {
None => PhaseItemExtraIndex::NONE,
Some(first_indirect_parameters_index) => {
PhaseItemExtraIndex::indirect_parameters_index(
u32::from(*first_indirect_parameters_index)
+ entity_index as u32,
)
}
},
},
UnbatchableBinnedEntityIndexSet::Dense(ref dynamic_offsets) => {
dynamic_offsets[entity_index]
}
};
let binned_phase_item = BPI::new(
key.clone(),
entity,
unbatchable_dynamic_offset.instance_index
..(unbatchable_dynamic_offset.instance_index + 1),
unbatchable_dynamic_offset.extra_index,
);
// Fetch the draw function.
let Some(draw_function) = draw_functions.get_mut(binned_phase_item.draw_function())
else {
continue;
};
draw_function.draw(world, render_pass, view, &binned_phase_item);
}
}
}
/// Renders all objects of type [`BinnedRenderPhaseType::NonMesh`].
///
/// These will have been added by plugins or the application.
fn render_non_meshes<'w>(
&self,
render_pass: &mut TrackedRenderPass<'w>,
world: &'w World,
view: Entity,
) {
let draw_functions = world.resource::<DrawFunctions<BPI>>();
let mut draw_functions = draw_functions.write();
for &(ref key, entity) in &self.non_mesh_items {
// Come up with a fake batch range and extra index. The draw
// function is expected to manage any sort of batching logic itself.
let binned_phase_item = BPI::new(key.clone(), entity, 0..1, PhaseItemExtraIndex(0));
let Some(draw_function) = draw_functions.get_mut(binned_phase_item.draw_function())
else {
continue;
};
draw_function.draw(world, render_pass, view, &binned_phase_item);
}
}
pub fn is_empty(&self) -> bool {
self.batchable_mesh_keys.is_empty()
&& self.unbatchable_mesh_keys.is_empty()
&& self.non_mesh_items.is_empty()
}
pub fn clear(&mut self) {
self.batchable_mesh_keys.clear();
self.batchable_mesh_values.clear();
self.unbatchable_mesh_keys.clear();
self.unbatchable_mesh_values.clear();
self.non_mesh_items.clear();
self.batch_sets.clear();
}
}
impl<BPI> Default for BinnedRenderPhase<BPI>
where
BPI: BinnedPhaseItem,
{
fn default() -> Self {
Self {
batchable_mesh_keys: vec![],
batchable_mesh_values: HashMap::default(),
unbatchable_mesh_keys: vec![],
unbatchable_mesh_values: HashMap::default(),
non_mesh_items: vec![],
batch_sets: vec![],
}
}
}
impl UnbatchableBinnedEntityIndexSet {
/// Returns the [`UnbatchableBinnedEntityIndices`] for the given entity.
fn indices_for_entity_index(
&self,
entity_index: u32,
) -> Option<UnbatchableBinnedEntityIndices> {
match self {
UnbatchableBinnedEntityIndexSet::NoEntities => None,
UnbatchableBinnedEntityIndexSet::Sparse { instance_range, .. }
if entity_index >= instance_range.len() as u32 =>
{
None
}
UnbatchableBinnedEntityIndexSet::Sparse {
instance_range,
first_indirect_parameters_index: None,
} => Some(UnbatchableBinnedEntityIndices {
instance_index: instance_range.start + entity_index,
extra_index: PhaseItemExtraIndex::NONE,
}),
UnbatchableBinnedEntityIndexSet::Sparse {
instance_range,
first_indirect_parameters_index: Some(first_indirect_parameters_index),
} => Some(UnbatchableBinnedEntityIndices {
instance_index: instance_range.start + entity_index,
extra_index: PhaseItemExtraIndex::indirect_parameters_index(
u32::from(*first_indirect_parameters_index) + entity_index,
),
}),
UnbatchableBinnedEntityIndexSet::Dense(ref indices) => {
indices.get(entity_index as usize).copied()
}
}
}
}
/// A convenient abstraction for adding all the systems necessary for a binned
/// render phase to the render app.
///
/// This is the version used when the pipeline supports GPU preprocessing: e.g.
/// 3D PBR meshes.
pub struct BinnedRenderPhasePlugin<BPI, GFBD>(PhantomData<(BPI, GFBD)>)
where
BPI: BinnedPhaseItem,
GFBD: GetFullBatchData;
impl<BPI, GFBD> Default for BinnedRenderPhasePlugin<BPI, GFBD>
where
BPI: BinnedPhaseItem,
GFBD: GetFullBatchData,
{
fn default() -> Self {
Self(PhantomData)
}
}
impl<BPI, GFBD> Plugin for BinnedRenderPhasePlugin<BPI, GFBD>
where
BPI: BinnedPhaseItem,
GFBD: GetFullBatchData + Sync + Send + 'static,
{
fn build(&self, app: &mut App) {
let Some(render_app) = app.get_sub_app_mut(RenderApp) else {
return;
};
render_app
.init_resource::<ViewBinnedRenderPhases<BPI>>()
.add_systems(
Render,
(
batching::sort_binned_render_phase::<BPI>.in_set(RenderSet::PhaseSort),
(
no_gpu_preprocessing::batch_and_prepare_binned_render_phase::<BPI, GFBD>
.run_if(resource_exists::<BatchedInstanceBuffer<GFBD::BufferData>>),
gpu_preprocessing::batch_and_prepare_binned_render_phase::<BPI, GFBD>
.run_if(
resource_exists::<
BatchedInstanceBuffers<GFBD::BufferData, GFBD::BufferInputData>,
>,
),
)
.in_set(RenderSet::PrepareResources),
),
);
}
}
/// Stores the rendering instructions for a single phase that sorts items in all
/// views.
///
/// They're cleared out every frame, but storing them in a resource like this
/// allows us to reuse allocations.
#[derive(Resource, Deref, DerefMut)]
pub struct ViewSortedRenderPhases<SPI>(pub EntityHashMap<SortedRenderPhase<SPI>>)
where
SPI: SortedPhaseItem;
impl<SPI> Default for ViewSortedRenderPhases<SPI>
where
SPI: SortedPhaseItem,
{
fn default() -> Self {
Self(default())
}
}
impl<SPI> ViewSortedRenderPhases<SPI>
where
SPI: SortedPhaseItem,
{
pub fn insert_or_clear(&mut self, entity: Entity) {
match self.entry(entity) {
Entry::Occupied(mut entry) => entry.get_mut().clear(),
Entry::Vacant(entry) => {
entry.insert(default());
}
}
}
}
/// A convenient abstraction for adding all the systems necessary for a sorted
/// render phase to the render app.
///
/// This is the version used when the pipeline supports GPU preprocessing: e.g.
/// 3D PBR meshes.
pub struct SortedRenderPhasePlugin<SPI, GFBD>(PhantomData<(SPI, GFBD)>)
where
SPI: SortedPhaseItem,
GFBD: GetFullBatchData;
impl<SPI, GFBD> Default for SortedRenderPhasePlugin<SPI, GFBD>
where
SPI: SortedPhaseItem,
GFBD: GetFullBatchData,
{
fn default() -> Self {
Self(PhantomData)
}
}
impl<SPI, GFBD> Plugin for SortedRenderPhasePlugin<SPI, GFBD>
where
SPI: SortedPhaseItem + CachedRenderPipelinePhaseItem,
GFBD: GetFullBatchData + Sync + Send + 'static,
{
fn build(&self, app: &mut App) {
let Some(render_app) = app.get_sub_app_mut(RenderApp) else {
return;
};
render_app
.init_resource::<ViewSortedRenderPhases<SPI>>()
.add_systems(
Render,
(
no_gpu_preprocessing::batch_and_prepare_sorted_render_phase::<SPI, GFBD>
.run_if(resource_exists::<BatchedInstanceBuffer<GFBD::BufferData>>),
gpu_preprocessing::batch_and_prepare_sorted_render_phase::<SPI, GFBD>.run_if(
resource_exists::<
BatchedInstanceBuffers<GFBD::BufferData, GFBD::BufferInputData>,
>,
),
)
.in_set(RenderSet::PrepareResources),
);
}
}
impl UnbatchableBinnedEntityIndexSet {
/// Adds a new entity to the list of unbatchable binned entities.
pub fn add(&mut self, indices: UnbatchableBinnedEntityIndices) {
match self {
UnbatchableBinnedEntityIndexSet::NoEntities => {
if indices.extra_index.is_dynamic_offset() {
// This is the first entity we've seen, and we don't have
// compute shaders. Initialize an array.
*self = UnbatchableBinnedEntityIndexSet::Dense(vec![indices]);
} else {
// This is the first entity we've seen, and we have compute
// shaders. Initialize the fast path.
*self = UnbatchableBinnedEntityIndexSet::Sparse {
instance_range: indices.instance_index..indices.instance_index + 1,
first_indirect_parameters_index: indices
.extra_index
.as_indirect_parameters_index()
.and_then(|index| NonMaxU32::try_from(index).ok()),
}
}
}
UnbatchableBinnedEntityIndexSet::Sparse {
ref mut instance_range,
first_indirect_parameters_index,
} if instance_range.end == indices.instance_index
&& ((first_indirect_parameters_index.is_none()
&& indices.extra_index == PhaseItemExtraIndex::NONE)
|| first_indirect_parameters_index.is_some_and(
|first_indirect_parameters_index| {
Some(
u32::from(first_indirect_parameters_index) + instance_range.end
- instance_range.start,
) == indices.extra_index.as_indirect_parameters_index()
},
)) =>
{
// This is the normal case on non-WebGL 2.
instance_range.end += 1;
}
UnbatchableBinnedEntityIndexSet::Sparse { instance_range, .. } => {
// We thought we were in non-WebGL 2 mode, but we got a dynamic
// offset or non-contiguous index anyway. This shouldn't happen,
// but let's go ahead and do the sensible thing anyhow: demote
// the compressed `NoDynamicOffsets` field to the full
// `DynamicOffsets` array.
let new_dynamic_offsets = (0..instance_range.len() as u32)
.flat_map(|entity_index| self.indices_for_entity_index(entity_index))
.chain(iter::once(indices))
.collect();
*self = UnbatchableBinnedEntityIndexSet::Dense(new_dynamic_offsets);
}
UnbatchableBinnedEntityIndexSet::Dense(ref mut dense_indices) => {
dense_indices.push(indices);
}
}
}
}
/// A collection of all items to be rendered that will be encoded to GPU
/// commands for a single render phase for a single view.
///
/// Each view (camera, or shadow-casting light, etc.) can have one or multiple render phases.
/// They are used to queue entities for rendering.
/// Multiple phases might be required due to different sorting/batching behaviors
/// (e.g. opaque: front to back, transparent: back to front) or because one phase depends on
/// the rendered texture of the previous phase (e.g. for screen-space reflections).
/// All [`PhaseItem`]s are then rendered using a single [`TrackedRenderPass`].
/// The render pass might be reused for multiple phases to reduce GPU overhead.
///
/// This flavor of render phase is used only for meshes that need to be sorted
/// back-to-front, such as transparent meshes. For items that don't need strict
/// sorting, [`BinnedRenderPhase`] is preferred, for performance.
pub struct SortedRenderPhase<I>
where
I: SortedPhaseItem,
{
/// The items within this [`SortedRenderPhase`].
pub items: Vec<I>,
}
impl<I> Default for SortedRenderPhase<I>
where
I: SortedPhaseItem,
{
fn default() -> Self {
Self { items: Vec::new() }
}
}
impl<I> SortedRenderPhase<I>
where
I: SortedPhaseItem,
{
/// Adds a [`PhaseItem`] to this render phase.
#[inline]
pub fn add(&mut self, item: I) {
self.items.push(item);
}
/// Removes all [`PhaseItem`]s from this render phase.
#[inline]
pub fn clear(&mut self) {
self.items.clear();
}
/// Sorts all of its [`PhaseItem`]s.
pub fn sort(&mut self) {
I::sort(&mut self.items);
}
/// An [`Iterator`] through the associated [`Entity`] for each [`PhaseItem`] in order.
#[inline]
pub fn iter_entities(&'_ self) -> impl Iterator<Item = Entity> + '_ {
self.items.iter().map(|item| item.entity())
}
/// Renders all of its [`PhaseItem`]s using their corresponding draw functions.
pub fn render<'w>(
&self,
render_pass: &mut TrackedRenderPass<'w>,
world: &'w World,
view: Entity,
) {
self.render_range(render_pass, world, view, ..);
}
/// Renders all [`PhaseItem`]s in the provided `range` (based on their index in `self.items`) using their corresponding draw functions.
pub fn render_range<'w>(
&self,
render_pass: &mut TrackedRenderPass<'w>,
world: &'w World,
view: Entity,
range: impl SliceIndex<[I], Output = [I]>,
) {
let items = self
.items
.get(range)
.expect("`Range` provided to `render_range()` is out of bounds");
let draw_functions = world.resource::<DrawFunctions<I>>();
let mut draw_functions = draw_functions.write();
draw_functions.prepare(world);
let mut index = 0;
while index < items.len() {
let item = &items[index];
let batch_range = item.batch_range();
if batch_range.is_empty() {
index += 1;
} else {
let draw_function = draw_functions.get_mut(item.draw_function()).unwrap();
draw_function.draw(world, render_pass, view, item);
index += batch_range.len();
}
}
}
}
/// An item (entity of the render world) which will be drawn to a texture or the screen,
/// as part of a render phase.
///
/// The data required for rendering an entity is extracted from the main world in the
/// [`ExtractSchedule`](crate::ExtractSchedule).
/// Then it has to be queued up for rendering during the [`RenderSet::Queue`],
/// by adding a corresponding phase item to a render phase.
/// Afterwards it will be possibly sorted and rendered automatically in the
/// [`RenderSet::PhaseSort`] and [`RenderSet::Render`], respectively.
///
/// `PhaseItem`s come in two flavors: [`BinnedPhaseItem`]s and
/// [`SortedPhaseItem`]s.
///
/// * Binned phase items have a `BinKey` which specifies what bin they're to be
/// placed in. All items in the same bin are eligible to be batched together.
/// The `BinKey`s are sorted, but the individual bin items aren't. Binned phase
/// items are good for opaque meshes, in which the order of rendering isn't
/// important. Generally, binned phase items are faster than sorted phase items.
///
/// * Sorted phase items, on the other hand, are placed into one large buffer
/// and then sorted all at once. This is needed for transparent meshes, which
/// have to be sorted back-to-front to render with the painter's algorithm.
/// These types of phase items are generally slower than binned phase items.
pub trait PhaseItem: Sized + Send + Sync + 'static {
/// Whether or not this `PhaseItem` should be subjected to automatic batching. (Default: `true`)
const AUTOMATIC_BATCHING: bool = true;
/// The corresponding entity that will be drawn.
///
/// This is used to fetch the render data of the entity, required by the draw function,
/// from the render world .
fn entity(&self) -> Entity;
/// Specifies the [`Draw`] function used to render the item.
fn draw_function(&self) -> DrawFunctionId;
/// The range of instances that the batch covers. After doing a batched draw, batch range
/// length phase items will be skipped. This design is to avoid having to restructure the
/// render phase unnecessarily.
fn batch_range(&self) -> &Range<u32>;
fn batch_range_mut(&mut self) -> &mut Range<u32>;
/// Returns the [`PhaseItemExtraIndex`].
///
/// If present, this is either a dynamic offset or an indirect parameters
/// index.
fn extra_index(&self) -> PhaseItemExtraIndex;
/// Returns a pair of mutable references to both the batch range and extra
/// index.
fn batch_range_and_extra_index_mut(&mut self) -> (&mut Range<u32>, &mut PhaseItemExtraIndex);
}
/// The "extra index" associated with some [`PhaseItem`]s, alongside the
/// indirect instance index.
///
/// Sometimes phase items require another index in addition to the range of
/// instances they already have. These can be:
///
/// * The *dynamic offset*: a `wgpu` dynamic offset into the uniform buffer of
/// instance data. This is used on platforms that don't support storage
/// buffers, to work around uniform buffer size limitations.
///
/// * The *indirect parameters index*: an index into the buffer that specifies
/// the indirect parameters for this [`PhaseItem`]'s drawcall. This is used when
/// indirect mode is on (as used for GPU culling).
///
/// Note that our indirect draw functionality requires storage buffers, so it's
/// impossible to have both a dynamic offset and an indirect parameters index.
/// This convenient fact allows us to pack both indices into a single `u32`.
#[derive(Clone, Copy, PartialEq, Eq, Hash)]
pub struct PhaseItemExtraIndex(pub u32);
impl Debug for PhaseItemExtraIndex {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
if self.is_dynamic_offset() {
write!(f, "DynamicOffset({})", self.offset())
} else if self.is_indirect_parameters_index() {
write!(f, "IndirectParametersIndex({})", self.offset())
} else {
write!(f, "None")
}
}
}
impl PhaseItemExtraIndex {
/// The flag that indicates that this index is an indirect parameter. If not
/// set, this is a dynamic offset.
pub const INDIRECT_PARAMETER_INDEX: u32 = 1 << 31;
/// To extract the index from a packed [`PhaseItemExtraIndex`], bitwise-and
/// the contents with this value.
pub const OFFSET_MASK: u32 = Self::INDIRECT_PARAMETER_INDEX - 1;
/// To extract the flag from a packed [`PhaseItemExtraIndex`], bitwise-and
/// the contents with this value.
pub const FLAGS_MASK: u32 = !Self::OFFSET_MASK;
/// The special value that indicates that no extra index is present.
pub const NONE: PhaseItemExtraIndex = PhaseItemExtraIndex(u32::MAX);
/// Returns either the indirect parameters index or the dynamic offset,
/// depending on which is in use.
#[inline]
fn offset(&self) -> u32 {
self.0 & Self::OFFSET_MASK
}
/// Determines whether this extra index is a dynamic offset.
#[inline]
fn is_dynamic_offset(&self) -> bool {
*self != Self::NONE && (self.0 & Self::INDIRECT_PARAMETER_INDEX) == 0
}
/// Determines whether this extra index is an indirect parameters index.
#[inline]
fn is_indirect_parameters_index(&self) -> bool {
*self != Self::NONE && (self.0 & Self::INDIRECT_PARAMETER_INDEX) != 0
}
/// Packs a indirect parameters index into this extra index.
#[inline]
pub fn indirect_parameters_index(indirect_parameter_index: u32) -> PhaseItemExtraIndex {
// Make sure we didn't overflow.
debug_assert_eq!(indirect_parameter_index & Self::FLAGS_MASK, 0);
PhaseItemExtraIndex(indirect_parameter_index | Self::INDIRECT_PARAMETER_INDEX)
}
/// Returns either an indirect parameters index or
/// [`PhaseItemExtraIndex::NONE`], as appropriate.
#[inline]
pub fn maybe_indirect_parameters_index(
maybe_indirect_parameters_index: Option<NonMaxU32>,
) -> PhaseItemExtraIndex {
match maybe_indirect_parameters_index {
Some(indirect_parameters_index) => {
Self::indirect_parameters_index(indirect_parameters_index.into())
}
None => PhaseItemExtraIndex::NONE,
}
}
/// Packs a dynamic offset into this extra index.
#[inline]
pub fn dynamic_offset(dynamic_offset: u32) -> PhaseItemExtraIndex {
// Make sure we didn't overflow.
debug_assert_eq!(dynamic_offset & Self::FLAGS_MASK, 0);
PhaseItemExtraIndex(dynamic_offset)
}
/// Returns either a dynamic offset or [`PhaseItemExtraIndex::NONE`], as
/// appropriate.
#[inline]
pub fn maybe_dynamic_offset(maybe_dynamic_offset: Option<NonMaxU32>) -> PhaseItemExtraIndex {
match maybe_dynamic_offset {
Some(dynamic_offset) => Self::dynamic_offset(dynamic_offset.into()),
None => PhaseItemExtraIndex::NONE,
}
}
/// If this extra index describes a dynamic offset, returns it; otherwise,
/// returns `None`.
#[inline]
pub fn as_dynamic_offset(&self) -> Option<NonMaxU32> {
if self.is_dynamic_offset() {
NonMaxU32::try_from(self.0 & Self::OFFSET_MASK).ok()
} else {
None
}
}
/// If this extra index describes an indirect parameters index, returns it;
/// otherwise, returns `None`.
#[inline]
pub fn as_indirect_parameters_index(&self) -> Option<u32> {
if self.is_indirect_parameters_index() {
Some(self.0 & Self::OFFSET_MASK)
} else {
None
}
}
}
/// Represents phase items that are placed into bins. The `BinKey` specifies
/// which bin they're to be placed in. Bin keys are sorted, and items within the
/// same bin are eligible to be batched together. The elements within the bins
/// aren't themselves sorted.
///
/// An example of a binned phase item is `Opaque3d`, for which the rendering
/// order isn't critical.
pub trait BinnedPhaseItem: PhaseItem {
/// The key used for binning [`PhaseItem`]s into bins. Order the members of
/// [`BinnedPhaseItem::BinKey`] by the order of binding for best
/// performance. For example, pipeline id, draw function id, mesh asset id,
/// lowest variable bind group id such as the material bind group id, and
/// its dynamic offsets if any, next bind group and offsets, etc. This
/// reduces the need for rebinding between bins and improves performance.
type BinKey: Clone + Send + Sync + Eq + Ord + Hash;
/// Creates a new binned phase item from the key and per-entity data.
///
/// Unlike [`SortedPhaseItem`]s, this is generally called "just in time"
/// before rendering. The resulting phase item isn't stored in any data
/// structures, resulting in significant memory savings.
fn new(
key: Self::BinKey,
representative_entity: Entity,
batch_range: Range<u32>,
extra_index: PhaseItemExtraIndex,
) -> Self;
}
/// Represents phase items that must be sorted. The `SortKey` specifies the
/// order that these items are drawn in. These are placed into a single array,
/// and the array as a whole is then sorted.
///
/// An example of a sorted phase item is `Transparent3d`, which must be sorted
/// back to front in order to correctly render with the painter's algorithm.
pub trait SortedPhaseItem: PhaseItem {
/// The type used for ordering the items. The smallest values are drawn first.
/// This order can be calculated using the [`ViewRangefinder3d`],
/// based on the view-space `Z` value of the corresponding view matrix.
type SortKey: Ord;
/// Determines the order in which the items are drawn.
fn sort_key(&self) -> Self::SortKey;
/// Sorts a slice of phase items into render order. Generally if the same type
/// is batched this should use a stable sort like [`slice::sort_by_key`].
/// In almost all other cases, this should not be altered from the default,
/// which uses a unstable sort, as this provides the best balance of CPU and GPU
/// performance.
///
/// Implementers can optionally not sort the list at all. This is generally advisable if and
/// only if the renderer supports a depth prepass, which is by default not supported by
/// the rest of Bevy's first party rendering crates. Even then, this may have a negative
/// impact on GPU-side performance due to overdraw.
///
/// It's advised to always profile for performance changes when changing this implementation.
#[inline]
fn sort(items: &mut [Self]) {
items.sort_unstable_by_key(|item| item.sort_key());
}
}
/// A [`PhaseItem`] item, that automatically sets the appropriate render pipeline,
/// cached in the [`PipelineCache`].
///
/// You can use the [`SetItemPipeline`] render command to set the pipeline for this item.
pub trait CachedRenderPipelinePhaseItem: PhaseItem {
/// The id of the render pipeline, cached in the [`PipelineCache`], that will be used to draw
/// this phase item.
fn cached_pipeline(&self) -> CachedRenderPipelineId;
}
/// A [`RenderCommand`] that sets the pipeline for the [`CachedRenderPipelinePhaseItem`].
pub struct SetItemPipeline;
impl<P: CachedRenderPipelinePhaseItem> RenderCommand<P> for SetItemPipeline {
type Param = SRes<PipelineCache>;
type ViewQuery = ();
type ItemQuery = ();
#[inline]
fn render<'w>(
item: &P,
_view: (),
_entity: Option<()>,
pipeline_cache: SystemParamItem<'w, '_, Self::Param>,
pass: &mut TrackedRenderPass<'w>,
) -> RenderCommandResult {
if let Some(pipeline) = pipeline_cache
.into_inner()
.get_render_pipeline(item.cached_pipeline())
{
pass.set_render_pipeline(pipeline);
RenderCommandResult::Success
} else {
RenderCommandResult::Failure
}
}
}
/// This system sorts the [`PhaseItem`]s of all [`SortedRenderPhase`]s of this
/// type.
pub fn sort_phase_system<I>(mut render_phases: ResMut<ViewSortedRenderPhases<I>>)
where
I: SortedPhaseItem,
{
for phase in render_phases.values_mut() {
phase.sort();
}
}
impl BinnedRenderPhaseType {
/// Creates the appropriate [`BinnedRenderPhaseType`] for a mesh, given its
/// batchability.
pub fn mesh(batchable: bool) -> BinnedRenderPhaseType {
if batchable {
BinnedRenderPhaseType::BatchableMesh
} else {
BinnedRenderPhaseType::UnbatchableMesh
}
}
}