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use crate::{
define_atomic_id,
render_asset::RenderAssets,
render_resource::{resource_macros::*, BindGroupLayout, Buffer, Sampler, TextureView},
renderer::RenderDevice,
texture::{FallbackImage, GpuImage},
};
pub use bevy_render_macros::AsBindGroup;
use encase::ShaderType;
use std::ops::Deref;
use thiserror::Error;
use wgpu::{BindGroupEntry, BindGroupLayoutEntry, BindingResource};
define_atomic_id!(BindGroupId);
render_resource_wrapper!(ErasedBindGroup, wgpu::BindGroup);
/// Bind groups are responsible for binding render resources (e.g. buffers, textures, samplers)
/// to a [`TrackedRenderPass`](crate::render_phase::TrackedRenderPass).
/// This makes them accessible in the pipeline (shaders) as uniforms.
///
/// May be converted from and dereferences to a wgpu [`BindGroup`](wgpu::BindGroup).
/// Can be created via [`RenderDevice::create_bind_group`](RenderDevice::create_bind_group).
#[derive(Clone, Debug)]
pub struct BindGroup {
id: BindGroupId,
value: ErasedBindGroup,
}
impl BindGroup {
/// Returns the [`BindGroupId`].
#[inline]
pub fn id(&self) -> BindGroupId {
self.id
}
}
impl From<wgpu::BindGroup> for BindGroup {
fn from(value: wgpu::BindGroup) -> Self {
BindGroup {
id: BindGroupId::new(),
value: ErasedBindGroup::new(value),
}
}
}
impl Deref for BindGroup {
type Target = wgpu::BindGroup;
#[inline]
fn deref(&self) -> &Self::Target {
&self.value
}
}
/// Converts a value to a [`BindGroup`] with a given [`BindGroupLayout`], which can then be used in Bevy shaders.
/// This trait can be derived (and generally should be). Read on for details and examples.
///
/// This is an opinionated trait that is intended to make it easy to generically
/// convert a type into a [`BindGroup`]. It provides access to specific render resources,
/// such as [`RenderAssets<GpuImage>`] and [`FallbackImage`]. If a type has a [`Handle<Image>`](bevy_asset::Handle),
/// these can be used to retrieve the corresponding [`Texture`](crate::render_resource::Texture) resource.
///
/// [`AsBindGroup::as_bind_group`] is intended to be called once, then the result cached somewhere. It is generally
/// ok to do "expensive" work here, such as creating a [`Buffer`] for a uniform.
///
/// If for some reason a [`BindGroup`] cannot be created yet (for example, the [`Texture`](crate::render_resource::Texture)
/// for an [`Image`](crate::texture::Image) hasn't loaded yet), just return [`AsBindGroupError::RetryNextUpdate`], which signals that the caller
/// should retry again later.
///
/// # Deriving
///
/// This trait can be derived. Field attributes like `uniform` and `texture` are used to define which fields should be bindings,
/// what their binding type is, and what index they should be bound at:
///
/// ```
/// # use bevy_render::{render_resource::*, texture::Image};
/// # use bevy_color::LinearRgba;
/// # use bevy_asset::Handle;
/// #[derive(AsBindGroup)]
/// struct CoolMaterial {
/// #[uniform(0)]
/// color: LinearRgba,
/// #[texture(1)]
/// #[sampler(2)]
/// color_texture: Handle<Image>,
/// #[storage(3, read_only)]
/// values: Vec<f32>,
/// #[storage(4, read_only, buffer)]
/// buffer: Buffer,
/// #[storage_texture(5)]
/// storage_texture: Handle<Image>,
/// }
/// ```
///
/// In WGSL shaders, the binding would look like this:
///
/// ```wgsl
/// @group(2) @binding(0) var<uniform> color: vec4<f32>;
/// @group(2) @binding(1) var color_texture: texture_2d<f32>;
/// @group(2) @binding(2) var color_sampler: sampler;
/// @group(2) @binding(3) var<storage> values: array<f32>;
/// @group(2) @binding(5) var storage_texture: texture_storage_2d<rgba8unorm, read_write>;
/// ```
/// Note that the "group" index is determined by the usage context. It is not defined in [`AsBindGroup`]. For example, in Bevy material bind groups
/// are generally bound to group 2.
///
/// The following field-level attributes are supported:
///
/// * `uniform(BINDING_INDEX)`
/// * The field will be converted to a shader-compatible type using the [`ShaderType`] trait, written to a [`Buffer`], and bound as a uniform.
/// [`ShaderType`] is implemented for most math types already, such as [`f32`], [`Vec4`](bevy_math::Vec4), and
/// [`LinearRgba`](bevy_color::LinearRgba). It can also be derived for custom structs.
///
/// * `texture(BINDING_INDEX, arguments)`
/// * This field's [`Handle<Image>`](bevy_asset::Handle) will be used to look up the matching [`Texture`](crate::render_resource::Texture)
/// GPU resource, which will be bound as a texture in shaders. The field will be assumed to implement [`Into<Option<Handle<Image>>>`]. In practice,
/// most fields should be a [`Handle<Image>`](bevy_asset::Handle) or [`Option<Handle<Image>>`]. If the value of an [`Option<Handle<Image>>`] is
/// [`None`], the [`FallbackImage`] resource will be used instead. This attribute can be used in conjunction with a `sampler` binding attribute
/// (with a different binding index) if a binding of the sampler for the [`Image`](crate::texture::Image) is also required.
///
/// | Arguments | Values | Default |
/// |-----------------------|-------------------------------------------------------------------------|----------------------|
/// | `dimension` = "..." | `"1d"`, `"2d"`, `"2d_array"`, `"3d"`, `"cube"`, `"cube_array"` | `"2d"` |
/// | `sample_type` = "..." | `"float"`, `"depth"`, `"s_int"` or `"u_int"` | `"float"` |
/// | `filterable` = ... | `true`, `false` | `true` |
/// | `multisampled` = ... | `true`, `false` | `false` |
/// | `visibility(...)` | `all`, `none`, or a list-combination of `vertex`, `fragment`, `compute` | `vertex`, `fragment` |
///
/// * `storage_texture(BINDING_INDEX, arguments)`
/// * This field's [`Handle<Image>`](bevy_asset::Handle) will be used to look up the matching [`Texture`](crate::render_resource::Texture)
/// GPU resource, which will be bound as a storage texture in shaders. The field will be assumed to implement [`Into<Option<Handle<Image>>>`]. In practice,
/// most fields should be a [`Handle<Image>`](bevy_asset::Handle) or [`Option<Handle<Image>>`]. If the value of an [`Option<Handle<Image>>`] is
/// [`None`], the [`FallbackImage`] resource will be used instead.
///
/// | Arguments | Values | Default |
/// |------------------------|--------------------------------------------------------------------------------------------|---------------|
/// | `dimension` = "..." | `"1d"`, `"2d"`, `"2d_array"`, `"3d"`, `"cube"`, `"cube_array"` | `"2d"` |
/// | `image_format` = ... | any member of [`TextureFormat`](crate::render_resource::TextureFormat) | `Rgba8Unorm` |
/// | `access` = ... | any member of [`StorageTextureAccess`](crate::render_resource::StorageTextureAccess) | `ReadWrite` |
/// | `visibility(...)` | `all`, `none`, or a list-combination of `vertex`, `fragment`, `compute` | `compute` |
///
/// * `sampler(BINDING_INDEX, arguments)`
/// * This field's [`Handle<Image>`](bevy_asset::Handle) will be used to look up the matching [`Sampler`] GPU
/// resource, which will be bound as a sampler in shaders. The field will be assumed to implement [`Into<Option<Handle<Image>>>`]. In practice,
/// most fields should be a [`Handle<Image>`](bevy_asset::Handle) or [`Option<Handle<Image>>`]. If the value of an [`Option<Handle<Image>>`] is
/// [`None`], the [`FallbackImage`] resource will be used instead. This attribute can be used in conjunction with a `texture` binding attribute
/// (with a different binding index) if a binding of the texture for the [`Image`](crate::texture::Image) is also required.
///
/// | Arguments | Values | Default |
/// |------------------------|-------------------------------------------------------------------------|------------------------|
/// | `sampler_type` = "..." | `"filtering"`, `"non_filtering"`, `"comparison"`. | `"filtering"` |
/// | `visibility(...)` | `all`, `none`, or a list-combination of `vertex`, `fragment`, `compute` | `vertex`, `fragment` |
///
/// * `storage(BINDING_INDEX, arguments)`
/// * The field will be converted to a shader-compatible type using the [`ShaderType`] trait, written to a [`Buffer`], and bound as a storage buffer.
/// * It supports and optional `read_only` parameter. Defaults to false if not present.
///
/// | Arguments | Values | Default |
/// |------------------------|-------------------------------------------------------------------------|----------------------|
/// | `visibility(...)` | `all`, `none`, or a list-combination of `vertex`, `fragment`, `compute` | `vertex`, `fragment` |
/// | `read_only` | if present then value is true, otherwise false | `false` |
///
/// Note that fields without field-level binding attributes will be ignored.
/// ```
/// # use bevy_render::{render_resource::AsBindGroup};
/// # use bevy_color::LinearRgba;
/// # use bevy_asset::Handle;
/// #[derive(AsBindGroup)]
/// struct CoolMaterial {
/// #[uniform(0)]
/// color: LinearRgba,
/// this_field_is_ignored: String,
/// }
/// ```
///
/// As mentioned above, [`Option<Handle<Image>>`] is also supported:
/// ```
/// # use bevy_render::{render_resource::AsBindGroup, texture::Image};
/// # use bevy_color::LinearRgba;
/// # use bevy_asset::Handle;
/// #[derive(AsBindGroup)]
/// struct CoolMaterial {
/// #[uniform(0)]
/// color: LinearRgba,
/// #[texture(1)]
/// #[sampler(2)]
/// color_texture: Option<Handle<Image>>,
/// }
/// ```
/// This is useful if you want a texture to be optional. When the value is [`None`], the [`FallbackImage`] will be used for the binding instead, which defaults
/// to "pure white".
///
/// Field uniforms with the same index will be combined into a single binding:
/// ```
/// # use bevy_render::{render_resource::AsBindGroup};
/// # use bevy_color::LinearRgba;
/// #[derive(AsBindGroup)]
/// struct CoolMaterial {
/// #[uniform(0)]
/// color: LinearRgba,
/// #[uniform(0)]
/// roughness: f32,
/// }
/// ```
///
/// In WGSL shaders, the binding would look like this:
/// ```wgsl
/// struct CoolMaterial {
/// color: vec4<f32>,
/// roughness: f32,
/// };
///
/// @group(2) @binding(0) var<uniform> material: CoolMaterial;
/// ```
///
/// Some less common scenarios will require "struct-level" attributes. These are the currently supported struct-level attributes:
/// * `uniform(BINDING_INDEX, ConvertedShaderType)`
/// * This also creates a [`Buffer`] using [`ShaderType`] and binds it as a uniform, much
/// much like the field-level `uniform` attribute. The difference is that the entire [`AsBindGroup`] value is converted to `ConvertedShaderType`,
/// which must implement [`ShaderType`], instead of a specific field implementing [`ShaderType`]. This is useful if more complicated conversion
/// logic is required. The conversion is done using the [`AsBindGroupShaderType<ConvertedShaderType>`] trait, which is automatically implemented
/// if `&Self` implements [`Into<ConvertedShaderType>`]. Only use [`AsBindGroupShaderType`] if access to resources like [`RenderAssets<GpuImage>`] is
/// required.
/// * `bind_group_data(DataType)`
/// * The [`AsBindGroup`] type will be converted to some `DataType` using [`Into<DataType>`] and stored
/// as [`AsBindGroup::Data`] as part of the [`AsBindGroup::as_bind_group`] call. This is useful if data needs to be stored alongside
/// the generated bind group, such as a unique identifier for a material's bind group. The most common use case for this attribute
/// is "shader pipeline specialization". See [`SpecializedRenderPipeline`](crate::render_resource::SpecializedRenderPipeline).
///
/// The previous `CoolMaterial` example illustrating "combining multiple field-level uniform attributes with the same binding index" can
/// also be equivalently represented with a single struct-level uniform attribute:
/// ```
/// # use bevy_render::{render_resource::{AsBindGroup, ShaderType}};
/// # use bevy_color::LinearRgba;
/// #[derive(AsBindGroup)]
/// #[uniform(0, CoolMaterialUniform)]
/// struct CoolMaterial {
/// color: LinearRgba,
/// roughness: f32,
/// }
///
/// #[derive(ShaderType)]
/// struct CoolMaterialUniform {
/// color: LinearRgba,
/// roughness: f32,
/// }
///
/// impl From<&CoolMaterial> for CoolMaterialUniform {
/// fn from(material: &CoolMaterial) -> CoolMaterialUniform {
/// CoolMaterialUniform {
/// color: material.color,
/// roughness: material.roughness,
/// }
/// }
/// }
/// ```
///
/// Setting `bind_group_data` looks like this:
/// ```
/// # use bevy_render::{render_resource::AsBindGroup};
/// # use bevy_color::LinearRgba;
/// #[derive(AsBindGroup)]
/// #[bind_group_data(CoolMaterialKey)]
/// struct CoolMaterial {
/// #[uniform(0)]
/// color: LinearRgba,
/// is_shaded: bool,
/// }
///
/// #[derive(Copy, Clone, Hash, Eq, PartialEq)]
/// struct CoolMaterialKey {
/// is_shaded: bool,
/// }
///
/// impl From<&CoolMaterial> for CoolMaterialKey {
/// fn from(material: &CoolMaterial) -> CoolMaterialKey {
/// CoolMaterialKey {
/// is_shaded: material.is_shaded,
/// }
/// }
/// }
/// ```
pub trait AsBindGroup {
/// Data that will be stored alongside the "prepared" bind group.
type Data: Send + Sync;
/// label
fn label() -> Option<&'static str> {
None
}
/// Creates a bind group for `self` matching the layout defined in [`AsBindGroup::bind_group_layout`].
fn as_bind_group(
&self,
layout: &BindGroupLayout,
render_device: &RenderDevice,
images: &RenderAssets<GpuImage>,
fallback_image: &FallbackImage,
) -> Result<PreparedBindGroup<Self::Data>, AsBindGroupError> {
let UnpreparedBindGroup { bindings, data } =
Self::unprepared_bind_group(self, layout, render_device, images, fallback_image)?;
let entries = bindings
.iter()
.map(|(index, binding)| BindGroupEntry {
binding: *index,
resource: binding.get_binding(),
})
.collect::<Vec<_>>();
let bind_group = render_device.create_bind_group(Self::label(), layout, &entries);
Ok(PreparedBindGroup {
bindings,
bind_group,
data,
})
}
/// Returns a vec of (binding index, `OwnedBindingResource`).
/// In cases where `OwnedBindingResource` is not available (as for bindless texture arrays currently),
/// an implementor may define `as_bind_group` directly. This may prevent certain features
/// from working correctly.
fn unprepared_bind_group(
&self,
layout: &BindGroupLayout,
render_device: &RenderDevice,
images: &RenderAssets<GpuImage>,
fallback_image: &FallbackImage,
) -> Result<UnpreparedBindGroup<Self::Data>, AsBindGroupError>;
/// Creates the bind group layout matching all bind groups returned by [`AsBindGroup::as_bind_group`]
fn bind_group_layout(render_device: &RenderDevice) -> BindGroupLayout
where
Self: Sized,
{
render_device.create_bind_group_layout(
Self::label(),
&Self::bind_group_layout_entries(render_device),
)
}
/// Returns a vec of bind group layout entries
fn bind_group_layout_entries(render_device: &RenderDevice) -> Vec<BindGroupLayoutEntry>
where
Self: Sized;
}
/// An error that occurs during [`AsBindGroup::as_bind_group`] calls.
#[derive(Debug, Error)]
pub enum AsBindGroupError {
/// The bind group could not be generated. Try again next frame.
#[error("The bind group could not be generated")]
RetryNextUpdate,
}
/// A prepared bind group returned as a result of [`AsBindGroup::as_bind_group`].
pub struct PreparedBindGroup<T> {
pub bindings: Vec<(u32, OwnedBindingResource)>,
pub bind_group: BindGroup,
pub data: T,
}
/// a map containing `OwnedBindingResource`s, keyed by the target binding index
pub struct UnpreparedBindGroup<T> {
pub bindings: Vec<(u32, OwnedBindingResource)>,
pub data: T,
}
/// An owned binding resource of any type (ex: a [`Buffer`], [`TextureView`], etc).
/// This is used by types like [`PreparedBindGroup`] to hold a single list of all
/// render resources used by bindings.
#[derive(Debug)]
pub enum OwnedBindingResource {
Buffer(Buffer),
TextureView(TextureView),
Sampler(Sampler),
}
impl OwnedBindingResource {
pub fn get_binding(&self) -> BindingResource {
match self {
OwnedBindingResource::Buffer(buffer) => buffer.as_entire_binding(),
OwnedBindingResource::TextureView(view) => BindingResource::TextureView(view),
OwnedBindingResource::Sampler(sampler) => BindingResource::Sampler(sampler),
}
}
}
/// Converts a value to a [`ShaderType`] for use in a bind group.
/// This is automatically implemented for references that implement [`Into`].
/// Generally normal [`Into`] / [`From`] impls should be preferred, but
/// sometimes additional runtime metadata is required.
/// This exists largely to make some [`AsBindGroup`] use cases easier.
pub trait AsBindGroupShaderType<T: ShaderType> {
/// Return the `T` [`ShaderType`] for `self`. When used in [`AsBindGroup`]
/// derives, it is safe to assume that all images in `self` exist.
fn as_bind_group_shader_type(&self, images: &RenderAssets<GpuImage>) -> T;
}
impl<T, U: ShaderType> AsBindGroupShaderType<U> for T
where
for<'a> &'a T: Into<U>,
{
#[inline]
fn as_bind_group_shader_type(&self, _images: &RenderAssets<GpuImage>) -> U {
self.into()
}
}
#[cfg(test)]
mod test {
use super::*;
use crate::{self as bevy_render, prelude::Image};
use bevy_asset::Handle;
#[test]
fn texture_visibility() {
#[derive(AsBindGroup)]
pub struct TextureVisibilityTest {
#[texture(0, visibility(all))]
pub all: Handle<Image>,
#[texture(1, visibility(none))]
pub none: Handle<Image>,
#[texture(2, visibility(fragment))]
pub fragment: Handle<Image>,
#[texture(3, visibility(vertex))]
pub vertex: Handle<Image>,
#[texture(4, visibility(compute))]
pub compute: Handle<Image>,
#[texture(5, visibility(vertex, fragment))]
pub vertex_fragment: Handle<Image>,
#[texture(6, visibility(vertex, compute))]
pub vertex_compute: Handle<Image>,
#[texture(7, visibility(fragment, compute))]
pub fragment_compute: Handle<Image>,
#[texture(8, visibility(vertex, fragment, compute))]
pub vertex_fragment_compute: Handle<Image>,
}
}
}