bevy_render/
globals.rs

1use crate::{
2    extract_resource::ExtractResource,
3    prelude::Shader,
4    render_resource::{ShaderType, UniformBuffer},
5    renderer::{RenderDevice, RenderQueue},
6    Extract, ExtractSchedule, Render, RenderApp, RenderSet,
7};
8use bevy_app::{App, Plugin};
9use bevy_asset::{load_internal_asset, weak_handle, Handle};
10use bevy_diagnostic::FrameCount;
11use bevy_ecs::prelude::*;
12use bevy_reflect::prelude::*;
13use bevy_time::Time;
14
15pub const GLOBALS_TYPE_HANDLE: Handle<Shader> =
16    weak_handle!("9e22a765-30ca-4070-9a4c-34ac08f1c0e7");
17
18pub struct GlobalsPlugin;
19
20impl Plugin for GlobalsPlugin {
21    fn build(&self, app: &mut App) {
22        load_internal_asset!(app, GLOBALS_TYPE_HANDLE, "globals.wgsl", Shader::from_wgsl);
23        app.register_type::<GlobalsUniform>();
24
25        if let Some(render_app) = app.get_sub_app_mut(RenderApp) {
26            render_app
27                .init_resource::<GlobalsBuffer>()
28                .init_resource::<Time>()
29                .add_systems(ExtractSchedule, (extract_frame_count, extract_time))
30                .add_systems(
31                    Render,
32                    prepare_globals_buffer.in_set(RenderSet::PrepareResources),
33                );
34        }
35    }
36}
37
38fn extract_frame_count(mut commands: Commands, frame_count: Extract<Res<FrameCount>>) {
39    commands.insert_resource(**frame_count);
40}
41
42fn extract_time(mut commands: Commands, time: Extract<Res<Time>>) {
43    commands.insert_resource(**time);
44}
45
46/// Contains global values useful when writing shaders.
47/// Currently only contains values related to time.
48#[derive(Default, Clone, Resource, ExtractResource, Reflect, ShaderType)]
49#[reflect(Resource, Default, Clone)]
50pub struct GlobalsUniform {
51    /// The time since startup in seconds.
52    /// Wraps to 0 after 1 hour.
53    time: f32,
54    /// The delta time since the previous frame in seconds
55    delta_time: f32,
56    /// Frame count since the start of the app.
57    /// It wraps to zero when it reaches the maximum value of a u32.
58    frame_count: u32,
59    /// WebGL2 structs must be 16 byte aligned.
60    #[cfg(all(feature = "webgl", target_arch = "wasm32", not(feature = "webgpu")))]
61    _wasm_padding: f32,
62}
63
64/// The buffer containing the [`GlobalsUniform`]
65#[derive(Resource, Default)]
66pub struct GlobalsBuffer {
67    pub buffer: UniformBuffer<GlobalsUniform>,
68}
69
70fn prepare_globals_buffer(
71    render_device: Res<RenderDevice>,
72    render_queue: Res<RenderQueue>,
73    mut globals_buffer: ResMut<GlobalsBuffer>,
74    time: Res<Time>,
75    frame_count: Res<FrameCount>,
76) {
77    let buffer = globals_buffer.buffer.get_mut();
78    buffer.time = time.elapsed_secs_wrapped();
79    buffer.delta_time = time.delta_secs();
80    buffer.frame_count = frame_count.0;
81
82    globals_buffer
83        .buffer
84        .write_buffer(&render_device, &render_queue);
85}
bevy_render/globals.rs

bevy_render/
globals.rs
