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Add user supplied mesh tag (#17648)

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# Objective

Because of mesh preprocessing, users cannot rely on
`@builtin(instance_index)` in order to reference external data, as the
instance index is not stable, either from frame to frame or relative to
the total spawn order of mesh instances.

## Solution

Add a user supplied mesh index that can be used for referencing external
data when drawing instanced meshes.

Closes #13373

## Testing

Benchmarked `many_cubes` showing no difference in total frame time.

## Showcase



https://github.com/user-attachments/assets/80620147-aafc-4d9d-a8ee-e2149f7c8f3b

---------

Co-authored-by: IceSentry <IceSentry@users.noreply.github.com>
This commit is contained in:
charlotte 2025-02-10 14:38:13 -08:00 committed by GitHub
parent 71b22397da
commit a861452d68
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GPG Key ID: B5690EEEBB952194
15 changed files with 196 additions and 68 deletions
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43
assets/shaders/automatic_instancing.wgsl Normal file
View File

@ -0,0 +1,43 @@
#import bevy_pbr::{
mesh_functions,
view_transformations::position_world_to_clip
}
@group(2) @binding(0) var texture: texture_2d<f32>;
@group(2) @binding(1) var texture_sampler: sampler;
struct Vertex {
@builtin(instance_index) instance_index: u32,
@location(0) position: vec3<f32>,
};
struct VertexOutput {
@builtin(position) clip_position: vec4<f32>,
@location(0) world_position: vec4<f32>,
@location(1) color: vec4<f32>,
};
@vertex
fn vertex(vertex: Vertex) -> VertexOutput {
var out: VertexOutput;
// Lookup the tag for the given mesh
let tag = mesh_functions::get_tag(vertex.instance_index);
var world_from_local = mesh_functions::get_world_from_local(vertex.instance_index);
out.world_position = mesh_functions::mesh_position_local_to_world(world_from_local, vec4(vertex.position, 1.0));
out.clip_position = position_world_to_clip(out.world_position.xyz);
let tex_dim = textureDimensions(texture);
// Find the texel coordinate as derived from the tag
let texel_coord = vec2<u32>(tag % tex_dim.x, tag / tex_dim.x);
out.color = textureLoad(texture, texel_coord, 0);
return out;
}
@fragment
fn fragment(
mesh: VertexOutput,
) -> @location(0) vec4<f32> {
return mesh.color;
}

4
assets/shaders/storage_buffer.wgsl
View File

@ -4,7 +4,6 @@
}
@group(2) @binding(0) var<storage, read> colors: array<vec4<f32>, 5>;
@group(2) @binding(1) var<uniform> color_id: u32;
struct Vertex {
@builtin(instance_index) instance_index: u32,
@ -20,11 +19,12 @@ struct VertexOutput {
@vertex
fn vertex(vertex: Vertex) -> VertexOutput {
var out: VertexOutput;
let tag = mesh_functions::get_tag(vertex.instance_index);
var world_from_local = mesh_functions::get_world_from_local(vertex.instance_index);
out.world_position = mesh_functions::mesh_position_local_to_world(world_from_local, vec4(vertex.position, 1.0));
out.clip_position = position_world_to_clip(out.world_position.xyz);
out.color = colors[color_id];
out.color = colors[tag];
return out;
}

1
crates/bevy_pbr/src/meshlet/instance_manager.rs
View File

@ -125,6 +125,7 @@ impl InstanceManager {
None,
None,
None,
None,
);
// Append instance data

26
crates/bevy_pbr/src/render/mesh.rs
View File

@ -485,6 +485,8 @@ pub struct MeshUniform {
/// Low 16 bits: index of the material inside the bind group data.
/// High 16 bits: index of the lightmap in the binding array.
pub material_and_lightmap_bind_group_slot: u32,
/// User supplied tag to identify this mesh instance.
pub tag: u32,
}
/// Information that has to be transferred from CPU to GPU in order to produce
@ -541,10 +543,10 @@ pub struct MeshInputUniform {
/// Low 16 bits: index of the material inside the bind group data.
/// High 16 bits: index of the lightmap in the binding array.
pub material_and_lightmap_bind_group_slot: u32,
/// User supplied tag to identify this mesh instance.
pub tag: u32,
/// Padding.
pub pad_a: u32,
/// Padding.
pub pad_b: u32,
pub pad: u32,
}
/// Information about each mesh instance needed to cull it on GPU.
@ -578,6 +580,7 @@ impl MeshUniform {
maybe_lightmap: Option<(LightmapSlotIndex, Rect)>,
current_skin_index: Option<u32>,
previous_skin_index: Option<u32>,
tag: Option<u32>,
) -> Self {
let (local_from_world_transpose_a, local_from_world_transpose_b) =
mesh_transforms.world_from_local.inverse_transpose_3x3();
@ -598,6 +601,7 @@ impl MeshUniform {
previous_skin_index: previous_skin_index.unwrap_or(u32::MAX),
material_and_lightmap_bind_group_slot: u32::from(material_bind_group_slot)
| ((lightmap_bind_group_slot as u32) << 16),
tag: tag.unwrap_or(0),
}
}
}
@ -729,6 +733,8 @@ pub struct RenderMeshInstanceShared {
/// Index of the slab that the lightmap resides in, if a lightmap is
/// present.
pub lightmap_slab_index: Option<LightmapSlabIndex>,
/// User supplied tag to identify this mesh instance.
pub tag: u32,
}
/// Information that is gathered during the parallel portion of mesh extraction
@ -808,6 +814,7 @@ impl RenderMeshInstanceShared {
fn from_components(
previous_transform: Option<&PreviousGlobalTransform>,
mesh: &Mesh3d,
tag: Option<&MeshTag>,
not_shadow_caster: bool,
no_automatic_batching: bool,
) -> Self {
@ -828,6 +835,7 @@ impl RenderMeshInstanceShared {
// This gets filled in later, during `RenderMeshGpuBuilder::update`.
material_bindings_index: default(),
lightmap_slab_index: None,
tag: tag.map_or(0, |i| **i),
}
}
@ -1160,8 +1168,8 @@ impl RenderMeshInstanceGpuBuilder {
material_and_lightmap_bind_group_slot: u32::from(
self.shared.material_bindings_index.slot,
) | ((lightmap_slot as u32) << 16),
pad_a: 0,
pad_b: 0,
tag: self.shared.tag,
pad: 0,
};
// Did the last frame contain this entity as well?
@ -1296,6 +1304,7 @@ pub fn extract_meshes_for_cpu_building(
&GlobalTransform,
Option<&PreviousGlobalTransform>,
&Mesh3d,
Option<&MeshTag>,
Has<NoFrustumCulling>,
Has<NotShadowReceiver>,
Has<TransmittedShadowReceiver>,
@ -1314,6 +1323,7 @@ pub fn extract_meshes_for_cpu_building(
transform,
previous_transform,
mesh,
tag,
no_frustum_culling,
not_shadow_receiver,
transmitted_receiver,
@ -1341,6 +1351,7 @@ pub fn extract_meshes_for_cpu_building(
let shared = RenderMeshInstanceShared::from_components(
previous_transform,
mesh,
tag,
not_shadow_caster,
no_automatic_batching,
);
@ -1402,6 +1413,7 @@ pub fn extract_meshes_for_gpu_building(
Option<&Lightmap>,
Option<&Aabb>,
&Mesh3d,
Option<&MeshTag>,
Has<NoFrustumCulling>,
Has<NotShadowReceiver>,
Has<TransmittedShadowReceiver>,
@ -1459,6 +1471,7 @@ pub fn extract_meshes_for_gpu_building(
lightmap,
aabb,
mesh,
tag,
no_frustum_culling,
not_shadow_receiver,
transmitted_receiver,
@ -1487,6 +1500,7 @@ pub fn extract_meshes_for_gpu_building(
let shared = RenderMeshInstanceShared::from_components(
previous_transform,
mesh,
tag,
not_shadow_caster,
no_automatic_batching,
);
@ -1840,6 +1854,7 @@ impl GetBatchData for MeshPipeline {
maybe_lightmap.map(|lightmap| (lightmap.slot_index, lightmap.uv_rect)),
current_skin_index,
previous_skin_index,
Some(mesh_instance.tag),
),
mesh_instance.should_batch().then_some((
material_bind_group_index.group,
@ -1907,6 +1922,7 @@ impl GetFullBatchData for MeshPipeline {
maybe_lightmap.map(|lightmap| (lightmap.slot_index, lightmap.uv_rect)),
current_skin_index,
previous_skin_index,
Some(mesh_instance.tag),
))
}

4
crates/bevy_pbr/src/render/mesh_functions.wgsl
View File

@ -132,3 +132,7 @@ fn get_visibility_range_dither_level(instance_index: u32, world_position: vec4<f
return offset + clamp(level, 0, 16);
}
#endif
fn get_tag(instance_index: u32) -> u32 {
return mesh[instance_index].tag;
}

1
crates/bevy_pbr/src/render/mesh_preprocess.wgsl
View File

@ -345,4 +345,5 @@ fn main(@builtin(global_invocation_id) global_invocation_id: vec3<u32>) {
output[mesh_output_index].previous_skin_index = current_input[input_index].previous_skin_index;
output[mesh_output_index].material_and_lightmap_bind_group_slot =
current_input[input_index].material_and_lightmap_bind_group_slot;
output[mesh_output_index].tag = current_input[input_index].tag;
}

2
crates/bevy_pbr/src/render/mesh_types.wgsl
View File

@ -22,6 +22,8 @@ struct Mesh {
// Low 16 bits: index of the material inside the bind group data.
// High 16 bits: index of the lightmap in the binding array.
material_and_lightmap_bind_group_slot: u32,
// User supplied index to identify the mesh instance
tag: u32,
};
#ifdef SKINNED

5
crates/bevy_render/src/experimental/occlusion_culling/mesh_preprocess_types.wgsl
View File

@ -19,8 +19,9 @@ struct MeshInput {
// Low 16 bits: index of the material inside the bind group data.
// High 16 bits: index of the lightmap in the binding array.
material_and_lightmap_bind_group_slot: u32,
pad_a: u32,
pad_b: u32,
// User supplied index to identify the mesh instance
tag: u32,
pad: u32,
}
// The `wgpu` indirect parameters structure. This is a union of two structures.

5
crates/bevy_render/src/mesh/components.rs
View File

@ -150,3 +150,8 @@ pub fn mark_3d_meshes_as_changed_if_their_assets_changed(
}
}
}
/// A component that stores an arbitrary index used to identify the mesh instance when rendering.
#[derive(Component, Clone, Debug, Default, Deref, DerefMut, Reflect, PartialEq, Eq)]
#[reflect(Component, Default)]
pub struct MeshTag(pub u32);

2
crates/bevy_render/src/mesh/mod.rs
View File

@ -21,7 +21,7 @@ use bevy_ecs::{
SystemParamItem,
},
};
pub use components::{mark_3d_meshes_as_changed_if_their_assets_changed, Mesh2d, Mesh3d};
pub use components::{mark_3d_meshes_as_changed_if_their_assets_changed, Mesh2d, Mesh3d, MeshTag};
use wgpu::IndexFormat;
/// Registers all [`MeshBuilder`] types.

19
crates/bevy_sprite/src/mesh2d/mesh.rs
View File

@ -19,6 +19,7 @@ use bevy_ecs::{
};
use bevy_image::{BevyDefault, Image, ImageSampler, TextureFormatPixelInfo};
use bevy_math::{Affine3, Vec4};
use bevy_render::mesh::MeshTag;
use bevy_render::prelude::Msaa;
use bevy_render::RenderSet::PrepareAssets;
use bevy_render::{
@ -230,10 +231,11 @@ pub struct Mesh2dUniform {
pub local_from_world_transpose_a: [Vec4; 2],
pub local_from_world_transpose_b: f32,
pub flags: u32,
pub tag: u32,
}
impl From<&Mesh2dTransforms> for Mesh2dUniform {
fn from(mesh_transforms: &Mesh2dTransforms) -> Self {
impl Mesh2dUniform {
fn from_components(mesh_transforms: &Mesh2dTransforms, tag: u32) -> Self {
let (local_from_world_transpose_a, local_from_world_transpose_b) =
mesh_transforms.world_from_local.inverse_transpose_3x3();
Self {
@ -241,6 +243,7 @@ impl From<&Mesh2dTransforms> for Mesh2dUniform {
local_from_world_transpose_a,
local_from_world_transpose_b,
flags: mesh_transforms.flags,
tag,
}
}
}
@ -259,6 +262,7 @@ pub struct RenderMesh2dInstance {
pub mesh_asset_id: AssetId<Mesh>,
pub material_bind_group_id: Material2dBindGroupId,
pub automatic_batching: bool,
pub tag: u32,
}
#[derive(Default, Resource, Deref, DerefMut)]
@ -275,13 +279,14 @@ pub fn extract_mesh2d(
&ViewVisibility,
&GlobalTransform,
&Mesh2d,
Option<&MeshTag>,
Has<NoAutomaticBatching>,
)>,
>,
) {
render_mesh_instances.clear();
for (entity, view_visibility, transform, handle, no_automatic_batching) in &query {
for (entity, view_visibility, transform, handle, tag, no_automatic_batching) in &query {
if !view_visibility.get() {
continue;
}
@ -295,6 +300,7 @@ pub fn extract_mesh2d(
mesh_asset_id: handle.0.id(),
material_bind_group_id: Material2dBindGroupId::default(),
automatic_batching: !no_automatic_batching,
tag: tag.map_or(0, |i| **i),
},
);
}
@ -422,7 +428,7 @@ impl GetBatchData for Mesh2dPipeline {
) -> Option<(Self::BufferData, Option<Self::CompareData>)> {
let mesh_instance = mesh_instances.get(&main_entity)?;
Some((
(&mesh_instance.transforms).into(),
Mesh2dUniform::from_components(&mesh_instance.transforms, mesh_instance.tag),
mesh_instance.automatic_batching.then_some((
mesh_instance.material_bind_group_id,
mesh_instance.mesh_asset_id,
@ -439,7 +445,10 @@ impl GetFullBatchData for Mesh2dPipeline {
main_entity: MainEntity,
) -> Option<Self::BufferData> {
let mesh_instance = mesh_instances.get(&main_entity)?;
Some((&mesh_instance.transforms).into())
Some(Mesh2dUniform::from_components(
&mesh_instance.transforms,
mesh_instance.tag,
))
}
fn get_index_and_compare_data(

1
examples/2d/mesh2d_manual.rs
View File

@ -352,6 +352,7 @@ pub fn extract_colored_mesh2d(
transforms,
material_bind_group_id: Material2dBindGroupId::default(),
automatic_batching: false,
tag: 0,
},
);
}

109
examples/shader/automatic_instancing.rs
View File

@ -1,51 +1,104 @@
//! Shows that multiple instances of a cube are automatically instanced in one draw call
//! Try running this example in a graphics profiler and all the cubes should be only a single draw call.
//! Also demonstrates how to use `MeshTag` to use external data in a custom material.
use bevy::prelude::*;
use bevy::{
prelude::*,
reflect::TypePath,
render::{
mesh::MeshTag,
render_resource::{AsBindGroup, ShaderRef},
},
};
const SHADER_ASSET_PATH: &str = "shaders/automatic_instancing.wgsl";
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_plugins((DefaultPlugins, MaterialPlugin::<CustomMaterial>::default()))
.add_systems(Startup, setup)
.add_systems(Update, update)
.run();
}
/// set up a simple 3D scene
/// Sets up an instanced grid of cubes, where each cube is colored based on an image that is
/// sampled in the vertex shader. The cubes are then animated in a spiral pattern.
///
/// This example demonstrates one use of automatic instancing and how to use `MeshTag` to use
/// external data in a custom material. For example, here we use the "index" of each cube to
/// determine the texel coordinate to sample from the image in the shader.
fn setup(
mut commands: Commands,
assets: Res<AssetServer>,
mut meshes: ResMut<Assets<Mesh>>,
mut materials: ResMut<Assets<StandardMaterial>>,
mut materials: ResMut<Assets<CustomMaterial>>,
) {
// camera
commands.spawn((
Camera3d::default(),
Transform::from_xyz(0.0, 48.0, 20.0).looking_at(Vec3::ZERO, Vec3::Y),
));
// light
commands.spawn((
PointLight {
shadows_enabled: true,
..default()
},
Transform::from_xyz(0.0, 16.0, 8.0),
));
// We will use this image as our external data for our material to sample from in the vertex shader
let image = assets.load("branding/icon.png");
let mesh = meshes.add(Cuboid::from_size(Vec3::splat(0.5)));
// This example uses the StandardMaterial but it can work with most custom material too
let material = materials.add(Color::srgb_u8(124, 144, 255));
// Our single mesh handle that will be instanced
let mesh_handle = meshes.add(Cuboid::from_size(Vec3::splat(0.01)));
// Create the custom material with a reference to our texture
// Automatic instancing works with any Material, including the `StandardMaterial`.
// This custom material is used to demonstrate the optional `MeshTag` feature.
let material_handle = materials.add(CustomMaterial {
image: image.clone(),
});
// We're hardcoding the image dimensions for simplicity
let image_dims = UVec2::new(256, 256);
let total_pixels = image_dims.x * image_dims.y;
for index in 0..total_pixels {
// Get x,y from index - x goes left to right, y goes top to bottom
let x = index % image_dims.x;
let y = index / image_dims.x;
// Convert to centered world coordinates
let world_x = (x as f32 - image_dims.x as f32 / 2.0) / 50.0;
let world_y = -((y as f32 - image_dims.y as f32 / 2.0) / 50.0); // Still need negative for world space
// spawn 1000 cubes
for x in -5..5 {
for y in -5..5 {
for z in -5..5 {
commands.spawn((
// For automatic instancing to take effect you need to
// use the same mesh handle and material handle for each instance
Mesh3d(mesh.clone()),
MeshMaterial3d(material.clone()),
Transform::from_xyz(x as f32, y as f32, z as f32),
Mesh3d(mesh_handle.clone()),
MeshMaterial3d(material_handle.clone()),
// This is an optional component that can be used to help tie external data to a mesh instance
MeshTag(index),
Transform::from_xyz(world_x, world_y, 0.0),
));
}
}
// Camera
commands.spawn((
Camera3d::default(),
Transform::from_xyz(0.0, 0.0, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
));
}
// Animate the transform
fn update(time: Res<Time>, mut transforms: Query<(&mut Transform, &MeshTag)>) {
for (mut transform, index) in transforms.iter_mut() {
// Animate the z position based on time using the index to create a spiral
transform.translation.z = ops::sin(time.elapsed_secs() + index.0 as f32 * 0.01);
}
}
// This struct defines the data that will be passed to your shader
#[derive(Asset, TypePath, AsBindGroup, Debug, Clone)]
struct CustomMaterial {
#[texture(0)]
#[sampler(1)]
image: Handle<Image>,
}
impl Material for CustomMaterial {
fn vertex_shader() -> ShaderRef {
SHADER_ASSET_PATH.into()
}
fn fragment_shader() -> ShaderRef {
SHADER_ASSET_PATH.into()
}
}

2
examples/shader/custom_render_phase.rs
View File

@ -372,6 +372,7 @@ impl GetBatchData for StencilPipeline {
current_skin_index: u32::MAX,
previous_skin_index: u32::MAX,
material_and_lightmap_bind_group_slot: 0,
tag: 0,
}
};
Some((mesh_uniform, None))
@ -425,6 +426,7 @@ impl GetFullBatchData for StencilPipeline {
None,
None,
None,
None,
))
}

32
examples/shader/storage_buffer.rs
View File

@ -1,10 +1,9 @@
//! This example demonstrates how to use a storage buffer with `AsBindGroup` in a custom material.
use std::array;
use bevy::{
prelude::*,
reflect::TypePath,
render::{
mesh::MeshTag,
render_resource::{AsBindGroup, ShaderRef},
storage::ShaderStorageBuffer,
},
@ -38,23 +37,22 @@ fn setup(
let colors = buffers.add(ShaderStorageBuffer::from(color_data));
let mesh_handle = meshes.add(Cuboid::from_size(Vec3::splat(0.3)));
// Create the custom material with the storage buffer
let material_handles: [Handle<CustomMaterial>; 5] = array::from_fn(|color_id| {
materials.add(CustomMaterial {
let material_handle = materials.add(CustomMaterial {
colors: colors.clone(),
color_id: color_id as u32,
})
});
commands.insert_resource(CustomMaterialHandles(material_handles.clone()));
commands.insert_resource(CustomMaterialHandle(material_handle.clone()));
// Spawn cubes with the custom material
let mut current_color_id = 0;
let mut current_color_id: u32 = 0;
for i in -6..=6 {
for j in -3..=3 {
commands.spawn((
Mesh3d(meshes.add(Cuboid::from_size(Vec3::splat(0.3)))),
MeshMaterial3d(material_handles[current_color_id % 5].clone()),
Mesh3d(mesh_handle.clone()),
MeshMaterial3d(material_handle.clone()),
MeshTag(current_color_id % 5),
Transform::from_xyz(i as f32, j as f32, 0.0),
));
current_color_id += 1;
@ -71,17 +69,11 @@ fn setup(
// Update the material color by time
fn update(
time: Res<Time>,
material_handles: Res<CustomMaterialHandles>,
material_handles: Res<CustomMaterialHandle>,
mut materials: ResMut<Assets<CustomMaterial>>,
mut buffers: ResMut<Assets<ShaderStorageBuffer>>,
) {
// All materials use the same buffer, so we only need to update one of them.
// But we do need to at least mark the others as changed, so that Bevy will
// reupload their contents to the GPU.
for material in &material_handles.0[1..] {
materials.get_mut(material);
}
let material = materials.get_mut(&material_handles.0[0]).unwrap();
let material = materials.get_mut(&material_handles.0).unwrap();
let buffer = buffers.get_mut(&material.colors).unwrap();
buffer.set_data(
@ -102,15 +94,13 @@ fn update(
// Holds handles to the custom materials
#[derive(Resource)]
struct CustomMaterialHandles([Handle<CustomMaterial>; 5]);
struct CustomMaterialHandle(Handle<CustomMaterial>);
// This struct defines the data that will be passed to your shader
#[derive(Asset, TypePath, AsBindGroup, Debug, Clone)]
struct CustomMaterial {
#[storage(0, read_only)]
colors: Handle<ShaderStorageBuffer>,
#[uniform(1)]
color_id: u32,
}
impl Material for CustomMaterial {