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texture_atlas.rs
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texture_atlas.rs
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//! In this example we generate four texture atlases (sprite sheets) from a folder containing
//! individual sprites.
//!
//! The texture atlases are generated with different padding and sampling to demonstrate the
//! effect of these settings, and how bleeding issues can be resolved by padding the sprites.
//!
//! Only one padded and one unpadded texture atlas are rendered to the screen.
//! An upscaled sprite from each of the four atlases are rendered to the screen.
use bevy::{asset::LoadedFolder, prelude::*, render::texture::ImageSampler};
fn main() {
App::new()
.add_plugins(DefaultPlugins.set(ImagePlugin::default_nearest())) // fallback to nearest sampling
.init_state::<AppState>()
.add_systems(OnEnter(AppState::Setup), load_textures)
.add_systems(Update, check_textures.run_if(in_state(AppState::Setup)))
.add_systems(OnEnter(AppState::Finished), setup)
.run();
}
#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Hash, States)]
enum AppState {
#[default]
Setup,
Finished,
}
#[derive(Resource, Default)]
struct RpgSpriteFolder(Handle<LoadedFolder>);
fn load_textures(mut commands: Commands, asset_server: Res<AssetServer>) {
// load multiple, individual sprites from a folder
commands.insert_resource(RpgSpriteFolder(asset_server.load_folder("textures/rpg")));
}
fn check_textures(
mut next_state: ResMut<NextState<AppState>>,
rpg_sprite_folder: Res<RpgSpriteFolder>,
mut events: EventReader<AssetEvent<LoadedFolder>>,
) {
// Advance the `AppState` once all sprite handles have been loaded by the `AssetServer`
for event in events.read() {
if event.is_loaded_with_dependencies(&rpg_sprite_folder.0) {
next_state.set(AppState::Finished);
}
}
}
fn setup(
mut commands: Commands,
rpg_sprite_handles: Res<RpgSpriteFolder>,
asset_server: Res<AssetServer>,
mut texture_atlases: ResMut<Assets<TextureAtlasLayout>>,
loaded_folders: Res<Assets<LoadedFolder>>,
mut textures: ResMut<Assets<Image>>,
) {
let loaded_folder = loaded_folders.get(&rpg_sprite_handles.0).unwrap();
// create texture atlases with different padding and sampling
let (texture_atlas_linear, linear_texture) = create_texture_atlas(
loaded_folder,
None,
Some(ImageSampler::linear()),
&mut textures,
);
let atlas_linear_handle = texture_atlases.add(texture_atlas_linear.clone());
let (texture_atlas_nearest, nearest_texture) = create_texture_atlas(
loaded_folder,
None,
Some(ImageSampler::nearest()),
&mut textures,
);
let atlas_nearest_handle = texture_atlases.add(texture_atlas_nearest);
let (texture_atlas_linear_padded, linear_padded_texture) = create_texture_atlas(
loaded_folder,
Some(UVec2::new(6, 6)),
Some(ImageSampler::linear()),
&mut textures,
);
let atlas_linear_padded_handle = texture_atlases.add(texture_atlas_linear_padded.clone());
let (texture_atlas_nearest_padded, nearest_padded_texture) = create_texture_atlas(
loaded_folder,
Some(UVec2::new(6, 6)),
Some(ImageSampler::nearest()),
&mut textures,
);
let atlas_nearest_padded_handle = texture_atlases.add(texture_atlas_nearest_padded);
// setup 2d scene
commands.spawn(Camera2dBundle::default());
// padded textures are to the right, unpadded to the left
// draw unpadded texture atlas
commands.spawn(SpriteBundle {
texture: linear_texture.clone(),
transform: Transform {
translation: Vec3::new(-250.0, -130.0, 0.0),
scale: Vec3::splat(0.8),
..default()
},
..default()
});
// draw padded texture atlas
commands.spawn(SpriteBundle {
texture: linear_padded_texture.clone(),
transform: Transform {
translation: Vec3::new(250.0, -130.0, 0.0),
scale: Vec3::splat(0.8),
..default()
},
..default()
});
let font = asset_server.load("fonts/FiraSans-Bold.ttf");
// padding label text style
let text_style: TextStyle = TextStyle {
font: font.clone(),
font_size: 50.0,
color: Color::WHITE,
};
// labels to indicate padding
// No padding
create_label(
&mut commands,
(-250.0, 330.0, 0.0),
"No padding",
text_style.clone(),
);
// Padding
create_label(&mut commands, (250.0, 330.0, 0.0), "Padding", text_style);
// get handle to a sprite to render
let vendor_handle: Handle<Image> = asset_server
.get_handle("textures/rpg/chars/vendor/generic-rpg-vendor.png")
.unwrap();
// get index of the sprite in the texture atlas, this is used to render the sprite
// the index is the same for all the texture atlases, since they are created from the same folder
let vendor_index = texture_atlas_linear
.get_texture_index(&vendor_handle)
.unwrap();
// configuration array to render sprites through iteration
let configurations: [(&str, Handle<TextureAtlasLayout>, Handle<Image>, f32); 4] = [
("Linear", atlas_linear_handle, linear_texture, -350.0),
("Nearest", atlas_nearest_handle, nearest_texture, -150.0),
(
"Linear",
atlas_linear_padded_handle,
linear_padded_texture,
150.0,
),
(
"Nearest",
atlas_nearest_padded_handle,
nearest_padded_texture,
350.0,
),
];
// label text style
let sampling_label_style = TextStyle {
font,
font_size: 30.0,
color: Color::WHITE,
};
let base_y = 170.0; // y position of the sprites
for (sampling, atlas_handle, image_handle, x) in configurations {
// render a sprite from the texture_atlas
create_sprite_from_atlas(
&mut commands,
(x, base_y, 0.0),
vendor_index,
atlas_handle,
image_handle,
);
// render a label to indicate the sampling setting
create_label(
&mut commands,
(x, base_y + 110.0, 0.0), // offset to y position of the sprite
sampling,
sampling_label_style.clone(),
);
}
}
/// Create a texture atlas with the given padding and sampling settings
/// from the individual sprites in the given folder.
fn create_texture_atlas(
folder: &LoadedFolder,
padding: Option<UVec2>,
sampling: Option<ImageSampler>,
textures: &mut ResMut<Assets<Image>>,
) -> (TextureAtlasLayout, Handle<Image>) {
// Build a texture atlas using the individual sprites
let mut texture_atlas_builder =
TextureAtlasBuilder::default().padding(padding.unwrap_or_default());
for handle in folder.handles.iter() {
let id = handle.id().typed_unchecked::<Image>();
let Some(texture) = textures.get(id) else {
warn!(
"{:?} did not resolve to an `Image` asset.",
handle.path().unwrap()
);
continue;
};
texture_atlas_builder.add_texture(Some(id), texture);
}
let (texture_atlas_layout, texture) = texture_atlas_builder.finish().unwrap();
let texture = textures.add(texture);
// Update the sampling settings of the texture atlas
let image = textures.get_mut(&texture).unwrap();
image.sampler = sampling.unwrap_or_default();
(texture_atlas_layout, texture)
}
/// Create and spawn a sprite from a texture atlas
fn create_sprite_from_atlas(
commands: &mut Commands,
translation: (f32, f32, f32),
sprite_index: usize,
atlas_handle: Handle<TextureAtlasLayout>,
texture: Handle<Image>,
) {
commands.spawn(SpriteSheetBundle {
transform: Transform {
translation: Vec3::new(translation.0, translation.1, translation.2),
scale: Vec3::splat(3.0),
..default()
},
texture,
atlas: TextureAtlas {
index: sprite_index,
layout: atlas_handle,
},
..default()
});
}
/// Create and spawn a label (text)
fn create_label(
commands: &mut Commands,
translation: (f32, f32, f32),
text: &str,
text_style: TextStyle,
) {
commands.spawn(Text2dBundle {
text: Text::from_section(text, text_style).with_justify(JustifyText::Center),
transform: Transform {
translation: Vec3::new(translation.0, translation.1, translation.2),
..default()
},
..default()
});
}