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render_to_texture.rs
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render_to_texture.rs
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//! Shows how to render to a texture. Useful for mirrors, UI, or exporting images.
use std::f32::consts::PI;
use bevy::{
prelude::*,
render::{
render_resource::{
Extent3d, TextureDescriptor, TextureDimension, TextureFormat, TextureUsages,
},
view::RenderLayers,
},
};
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_systems(Startup, setup)
.add_systems(Update, (cube_rotator_system, rotator_system))
.run();
}
// Marks the first pass cube (rendered to a texture.)
#[derive(Component)]
struct FirstPassCube;
// Marks the main pass cube, to which the texture is applied.
#[derive(Component)]
struct MainPassCube;
fn setup(
mut commands: Commands,
mut meshes: ResMut<Assets<Mesh>>,
mut materials: ResMut<Assets<StandardMaterial>>,
mut images: ResMut<Assets<Image>>,
) {
let size = Extent3d {
width: 512,
height: 512,
..default()
};
// This is the texture that will be rendered to.
let mut image = Image {
texture_descriptor: TextureDescriptor {
label: None,
size,
dimension: TextureDimension::D2,
format: TextureFormat::Bgra8UnormSrgb,
mip_level_count: 1,
sample_count: 1,
usage: TextureUsages::TEXTURE_BINDING
| TextureUsages::COPY_DST
| TextureUsages::RENDER_ATTACHMENT,
view_formats: &[],
},
..default()
};
// fill image.data with zeroes
image.resize(size);
let image_handle = images.add(image);
let cube_handle = meshes.add(Cuboid::new(4.0, 4.0, 4.0));
let cube_material_handle = materials.add(StandardMaterial {
base_color: Color::rgb(0.8, 0.7, 0.6),
reflectance: 0.02,
unlit: false,
..default()
});
// This specifies the layer used for the first pass, which will be attached to the first pass camera and cube.
let first_pass_layer = RenderLayers::layer(1);
// The cube that will be rendered to the texture.
commands.spawn((
PbrBundle {
mesh: cube_handle,
material: cube_material_handle,
transform: Transform::from_translation(Vec3::new(0.0, 0.0, 1.0)),
..default()
},
FirstPassCube,
first_pass_layer,
));
// Light
// NOTE: we add the light to all layers so it affects both the rendered-to-texture cube, and the cube on which we display the texture
// Setting the layer to RenderLayers::layer(0) would cause the main view to be lit, but the rendered-to-texture cube to be unlit.
// Setting the layer to RenderLayers::layer(1) would cause the rendered-to-texture cube to be lit, but the main view to be unlit.
commands.spawn((
PointLightBundle {
transform: Transform::from_translation(Vec3::new(0.0, 0.0, 10.0)),
..default()
},
RenderLayers::all(),
));
commands.spawn((
Camera3dBundle {
camera: Camera {
// render before the "main pass" camera
order: -1,
target: image_handle.clone().into(),
clear_color: Color::WHITE.into(),
..default()
},
transform: Transform::from_translation(Vec3::new(0.0, 0.0, 15.0))
.looking_at(Vec3::ZERO, Vec3::Y),
..default()
},
first_pass_layer,
));
let cube_size = 4.0;
let cube_handle = meshes.add(Cuboid::new(cube_size, cube_size, cube_size));
// This material has the texture that has been rendered.
let material_handle = materials.add(StandardMaterial {
base_color_texture: Some(image_handle),
reflectance: 0.02,
unlit: false,
..default()
});
// Main pass cube, with material containing the rendered first pass texture.
commands.spawn((
PbrBundle {
mesh: cube_handle,
material: material_handle,
transform: Transform::from_xyz(0.0, 0.0, 1.5)
.with_rotation(Quat::from_rotation_x(-PI / 5.0)),
..default()
},
MainPassCube,
));
// The main pass camera.
commands.spawn(Camera3dBundle {
transform: Transform::from_xyz(0.0, 0.0, 15.0).looking_at(Vec3::ZERO, Vec3::Y),
..default()
});
}
/// Rotates the inner cube (first pass)
fn rotator_system(time: Res<Time>, mut query: Query<&mut Transform, With<FirstPassCube>>) {
for mut transform in &mut query {
transform.rotate_x(1.5 * time.delta_seconds());
transform.rotate_z(1.3 * time.delta_seconds());
}
}
/// Rotates the outer cube (main pass)
fn cube_rotator_system(time: Res<Time>, mut query: Query<&mut Transform, With<MainPassCube>>) {
for mut transform in &mut query {
transform.rotate_x(1.0 * time.delta_seconds());
transform.rotate_y(0.7 * time.delta_seconds());
}
}