3ada15ee1c
# Objective Glam has some common and useful types and helpers that are not in the prelude of `bevy_math`. This includes shorthand constructors like `vec3`, or even `Vec3A`, the aligned version of `Vec3`. ```rust // The "normal" way to create a 3D vector let vec = Vec3::new(2.0, 1.0, -3.0); // Shorthand version let vec = vec3(2.0, 1.0, -3.0); ``` ## Solution Add the following types and methods to the prelude: - `vec2`, `vec3`, `vec3a`, `vec4` - `uvec2`, `uvec3`, `uvec4` - `ivec2`, `ivec3`, `ivec4` - `bvec2`, `bvec3`, `bvec3a`, `bvec4`, `bvec4a` - `mat2`, `mat3`, `mat3a`, `mat4` - `quat` (not sure if anyone uses this, but for consistency) - `Vec3A` - `BVec3A`, `BVec4A` - `Mat3A` I did not add the u16, i16, or f64 variants like `dvec2`, since there are currently no existing types like those in the prelude. The shorthand constructors are currently used a lot in some places in Bevy, and not at all in others. In a follow-up, we might want to consider if we have a preference for the shorthand, and make a PR to change the codebase to use it more consistently.
386 lines
14 KiB
Rust
386 lines
14 KiB
Rust
//! Demonstrates how to enqueue custom draw commands in a render phase.
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//!
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//! This example shows how to use the built-in
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//! [`bevy_render::render_phase::BinnedRenderPhase`] functionality with a
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//! custom [`RenderCommand`] to allow inserting arbitrary GPU drawing logic
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//! into Bevy's pipeline. This is not the only way to add custom rendering code
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//! into Bevy—render nodes are another, lower-level method—but it does allow
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//! for better reuse of parts of Bevy's built-in mesh rendering logic.
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use bevy::{
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core_pipeline::core_3d::{Opaque3d, Opaque3dBinKey, CORE_3D_DEPTH_FORMAT},
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ecs::{
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query::ROQueryItem,
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system::{lifetimeless::SRes, SystemParamItem},
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},
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prelude::*,
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render::{
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extract_component::{ExtractComponent, ExtractComponentPlugin},
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primitives::Aabb,
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render_phase::{
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AddRenderCommand, BinnedRenderPhaseType, DrawFunctions, PhaseItem, RenderCommand,
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RenderCommandResult, SetItemPipeline, TrackedRenderPass, ViewBinnedRenderPhases,
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},
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render_resource::{
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BufferUsages, ColorTargetState, ColorWrites, CompareFunction, DepthStencilState,
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FragmentState, IndexFormat, MultisampleState, PipelineCache, PrimitiveState,
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RawBufferVec, RenderPipelineDescriptor, SpecializedRenderPipeline,
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SpecializedRenderPipelines, TextureFormat, VertexAttribute, VertexBufferLayout,
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VertexFormat, VertexState, VertexStepMode,
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},
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renderer::{RenderDevice, RenderQueue},
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view::{self, ExtractedView, RenderVisibleEntities, VisibilitySystems},
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Render, RenderApp, RenderSet,
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},
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};
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use bytemuck::{Pod, Zeroable};
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/// A marker component that represents an entity that is to be rendered using
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/// our custom phase item.
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///
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/// Note the [`ExtractComponent`] trait implementation. This is necessary to
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/// tell Bevy that this object should be pulled into the render world.
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#[derive(Clone, Component, ExtractComponent)]
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struct CustomRenderedEntity;
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/// Holds a reference to our shader.
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///
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/// This is loaded at app creation time.
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#[derive(Resource)]
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struct CustomPhasePipeline {
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shader: Handle<Shader>,
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}
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/// A [`RenderCommand`] that binds the vertex and index buffers and issues the
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/// draw command for our custom phase item.
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struct DrawCustomPhaseItem;
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impl<P> RenderCommand<P> for DrawCustomPhaseItem
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where
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P: PhaseItem,
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{
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type Param = SRes<CustomPhaseItemBuffers>;
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type ViewQuery = ();
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type ItemQuery = ();
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fn render<'w>(
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_: &P,
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_: ROQueryItem<'w, Self::ViewQuery>,
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_: Option<ROQueryItem<'w, Self::ItemQuery>>,
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custom_phase_item_buffers: SystemParamItem<'w, '_, Self::Param>,
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pass: &mut TrackedRenderPass<'w>,
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) -> RenderCommandResult {
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// Borrow check workaround.
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let custom_phase_item_buffers = custom_phase_item_buffers.into_inner();
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// Tell the GPU where the vertices are.
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pass.set_vertex_buffer(
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0,
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custom_phase_item_buffers
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.vertices
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.buffer()
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.unwrap()
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.slice(..),
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);
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// Tell the GPU where the indices are.
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pass.set_index_buffer(
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custom_phase_item_buffers
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.indices
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.buffer()
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.unwrap()
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.slice(..),
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0,
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IndexFormat::Uint32,
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);
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// Draw one triangle (3 vertices).
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pass.draw_indexed(0..3, 0, 0..1);
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RenderCommandResult::Success
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}
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}
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/// The GPU vertex and index buffers for our custom phase item.
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///
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/// As the custom phase item is a single triangle, these are uploaded once and
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/// then left alone.
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#[derive(Resource)]
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struct CustomPhaseItemBuffers {
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/// The vertices for the single triangle.
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///
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/// This is a [`RawBufferVec`] because that's the simplest and fastest type
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/// of GPU buffer, and [`Vertex`] objects are simple.
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vertices: RawBufferVec<Vertex>,
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/// The indices of the single triangle.
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///
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/// As above, this is a [`RawBufferVec`] because `u32` values have trivial
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/// size and alignment.
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indices: RawBufferVec<u32>,
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}
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/// The CPU-side structure that describes a single vertex of the triangle.
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#[derive(Clone, Copy, Pod, Zeroable)]
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#[repr(C)]
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struct Vertex {
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/// The 3D position of the triangle vertex.
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position: Vec3,
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/// Padding.
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pad0: u32,
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/// The color of the triangle vertex.
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color: Vec3,
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/// Padding.
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pad1: u32,
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}
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impl Vertex {
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/// Creates a new vertex structure.
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const fn new(position: Vec3, color: Vec3) -> Vertex {
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Vertex {
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position,
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color,
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pad0: 0,
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pad1: 0,
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}
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}
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}
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/// The custom draw commands that Bevy executes for each entity we enqueue into
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/// the render phase.
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type DrawCustomPhaseItemCommands = (SetItemPipeline, DrawCustomPhaseItem);
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/// A query filter that tells [`view::check_visibility`] about our custom
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/// rendered entity.
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type WithCustomRenderedEntity = With<CustomRenderedEntity>;
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/// A single triangle's worth of vertices, for demonstration purposes.
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static VERTICES: [Vertex; 3] = [
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Vertex::new(vec3(-0.866, -0.5, 0.5), vec3(1.0, 0.0, 0.0)),
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Vertex::new(vec3(0.866, -0.5, 0.5), vec3(0.0, 1.0, 0.0)),
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Vertex::new(vec3(0.0, 1.0, 0.5), vec3(0.0, 0.0, 1.0)),
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];
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/// The entry point.
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fn main() {
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let mut app = App::new();
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app.add_plugins(DefaultPlugins)
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.add_plugins(ExtractComponentPlugin::<CustomRenderedEntity>::default())
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.add_systems(Startup, setup)
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// Make sure to tell Bevy to check our entity for visibility. Bevy won't
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// do this by default, for efficiency reasons.
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.add_systems(
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PostUpdate,
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view::check_visibility::<WithCustomRenderedEntity>
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.in_set(VisibilitySystems::CheckVisibility),
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);
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// We make sure to add these to the render app, not the main app.
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app.get_sub_app_mut(RenderApp)
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.unwrap()
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.init_resource::<CustomPhasePipeline>()
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.init_resource::<SpecializedRenderPipelines<CustomPhasePipeline>>()
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.add_render_command::<Opaque3d, DrawCustomPhaseItemCommands>()
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.add_systems(
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Render,
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prepare_custom_phase_item_buffers.in_set(RenderSet::Prepare),
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)
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.add_systems(Render, queue_custom_phase_item.in_set(RenderSet::Queue));
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app.run();
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}
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/// Spawns the objects in the scene.
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fn setup(mut commands: Commands) {
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// Spawn a single entity that has custom rendering. It'll be extracted into
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// the render world via [`ExtractComponent`].
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commands.spawn((
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Visibility::default(),
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Transform::default(),
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// This `Aabb` is necessary for the visibility checks to work.
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Aabb {
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center: Vec3A::ZERO,
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half_extents: Vec3A::splat(0.5),
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},
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CustomRenderedEntity,
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));
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// Spawn the camera.
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commands.spawn((
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Camera3d::default(),
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Transform::from_xyz(0.0, 0.0, 1.0).looking_at(Vec3::ZERO, Vec3::Y),
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));
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}
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/// Creates the [`CustomPhaseItemBuffers`] resource.
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///
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/// This must be done in a startup system because it needs the [`RenderDevice`]
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/// and [`RenderQueue`] to exist, and they don't until [`App::run`] is called.
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fn prepare_custom_phase_item_buffers(mut commands: Commands) {
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commands.init_resource::<CustomPhaseItemBuffers>();
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}
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/// A render-world system that enqueues the entity with custom rendering into
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/// the opaque render phases of each view.
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fn queue_custom_phase_item(
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pipeline_cache: Res<PipelineCache>,
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custom_phase_pipeline: Res<CustomPhasePipeline>,
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mut opaque_render_phases: ResMut<ViewBinnedRenderPhases<Opaque3d>>,
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opaque_draw_functions: Res<DrawFunctions<Opaque3d>>,
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mut specialized_render_pipelines: ResMut<SpecializedRenderPipelines<CustomPhasePipeline>>,
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views: Query<(Entity, &RenderVisibleEntities, &Msaa), With<ExtractedView>>,
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) {
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let draw_custom_phase_item = opaque_draw_functions
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.read()
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.id::<DrawCustomPhaseItemCommands>();
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// Render phases are per-view, so we need to iterate over all views so that
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// the entity appears in them. (In this example, we have only one view, but
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// it's good practice to loop over all views anyway.)
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for (view_entity, view_visible_entities, msaa) in views.iter() {
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let Some(opaque_phase) = opaque_render_phases.get_mut(&view_entity) else {
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continue;
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};
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// Find all the custom rendered entities that are visible from this
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// view.
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for &entity in view_visible_entities
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.get::<WithCustomRenderedEntity>()
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.iter()
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{
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// Ordinarily, the [`SpecializedRenderPipeline::Key`] would contain
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// some per-view settings, such as whether the view is HDR, but for
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// simplicity's sake we simply hard-code the view's characteristics,
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// with the exception of number of MSAA samples.
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let pipeline_id = specialized_render_pipelines.specialize(
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&pipeline_cache,
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&custom_phase_pipeline,
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*msaa,
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);
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// Add the custom render item. We use the
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// [`BinnedRenderPhaseType::NonMesh`] type to skip the special
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// handling that Bevy has for meshes (preprocessing, indirect
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// draws, etc.)
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//
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// The asset ID is arbitrary; we simply use [`AssetId::invalid`],
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// but you can use anything you like. Note that the asset ID need
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// not be the ID of a [`Mesh`].
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opaque_phase.add(
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Opaque3dBinKey {
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draw_function: draw_custom_phase_item,
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pipeline: pipeline_id,
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asset_id: AssetId::<Mesh>::invalid().untyped(),
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material_bind_group_id: None,
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lightmap_image: None,
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},
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entity,
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BinnedRenderPhaseType::NonMesh,
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);
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}
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}
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}
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impl SpecializedRenderPipeline for CustomPhasePipeline {
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type Key = Msaa;
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fn specialize(&self, msaa: Self::Key) -> RenderPipelineDescriptor {
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RenderPipelineDescriptor {
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label: Some("custom render pipeline".into()),
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layout: vec![],
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push_constant_ranges: vec![],
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vertex: VertexState {
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shader: self.shader.clone(),
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shader_defs: vec![],
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entry_point: "vertex".into(),
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buffers: vec![VertexBufferLayout {
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array_stride: size_of::<Vertex>() as u64,
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step_mode: VertexStepMode::Vertex,
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// This needs to match the layout of [`Vertex`].
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attributes: vec![
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VertexAttribute {
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format: VertexFormat::Float32x3,
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offset: 0,
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shader_location: 0,
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},
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VertexAttribute {
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format: VertexFormat::Float32x3,
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offset: 16,
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shader_location: 1,
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},
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],
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}],
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},
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fragment: Some(FragmentState {
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shader: self.shader.clone(),
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shader_defs: vec![],
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entry_point: "fragment".into(),
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targets: vec![Some(ColorTargetState {
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// Ordinarily, you'd want to check whether the view has the
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// HDR format and substitute the appropriate texture format
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// here, but we omit that for simplicity.
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format: TextureFormat::bevy_default(),
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blend: None,
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write_mask: ColorWrites::ALL,
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})],
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}),
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primitive: PrimitiveState::default(),
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// Note that if your view has no depth buffer this will need to be
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// changed.
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depth_stencil: Some(DepthStencilState {
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format: CORE_3D_DEPTH_FORMAT,
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depth_write_enabled: false,
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depth_compare: CompareFunction::Always,
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stencil: default(),
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bias: default(),
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}),
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multisample: MultisampleState {
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count: msaa.samples(),
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mask: !0,
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alpha_to_coverage_enabled: false,
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},
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zero_initialize_workgroup_memory: false,
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}
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}
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}
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impl FromWorld for CustomPhaseItemBuffers {
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fn from_world(world: &mut World) -> Self {
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let render_device = world.resource::<RenderDevice>();
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let render_queue = world.resource::<RenderQueue>();
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// Create the vertex and index buffers.
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let mut vbo = RawBufferVec::new(BufferUsages::VERTEX);
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let mut ibo = RawBufferVec::new(BufferUsages::INDEX);
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for vertex in &VERTICES {
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vbo.push(*vertex);
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}
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for index in 0..3 {
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ibo.push(index);
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}
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// These two lines are required in order to trigger the upload to GPU.
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vbo.write_buffer(render_device, render_queue);
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ibo.write_buffer(render_device, render_queue);
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CustomPhaseItemBuffers {
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vertices: vbo,
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indices: ibo,
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}
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}
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}
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impl FromWorld for CustomPhasePipeline {
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fn from_world(world: &mut World) -> Self {
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// Load and compile the shader in the background.
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let asset_server = world.resource::<AssetServer>();
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CustomPhasePipeline {
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shader: asset_server.load("shaders/custom_phase_item.wgsl"),
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}
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}
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}
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