bevy_pixel_camera

A simple camera plugin for the Bevy game engine, to help with the use of pixel-art sprites.

This crates provides a plugin to automatically configure Bevy's Camera2dBundle. It works by setting the camera to an integer scaling factor (using Bevy's ScalingMode::WindowSize), and automatically updating the zoom level so that the specified target resolution fills as much of the sceen as possible.

The plugin can also automatically set and resize the viewport of the camera to match the target resolution.

Comparison with other methods

There is two main methods to render pixel-art games: upscale each sprite independently, or render everything to an offscreen texture and only upscale this texture. This crate use the first method. There is advantages and drawbacks to both approaches.

Advantages of the "upscale each sprite independently" method (i.e. this crate):

• allows for smoother scrolling and movement of sprites, if you're willing to temporarily break the alignment on virtual pixels (this would be even more effective with a dedicated upscaling shader);
• easier to mix pixel-art and high resolution graphics (for example for text, particles or effects).

Advantages of the "offscreen texture" method:

• always ensure perfect alignment on virtual pixels (authentic "retro" look);
• may be more efficient (in most cases, the difference is probably negligible on modern computers).

How to use

Note that Bevy uses linear sampling by default for textures, which is not what you want for pixel art. The easiest way to change this is to configure Bevy's default plugins with ImagePlugin::default_nearest().

Also note that if either the width or the height of your sprite is not divisible by 2, you may need to change the anchor of the sprite (which is at the center by default), otherwise it won't be aligned with virtual pixels.

use bevy::prelude::*;
use bevy::sprite::Anchor;
use bevy_pixel_camera::{
    PixelCameraPlugin, PixelZoom, PixelViewport
};

fn main() {
    App::new()
        .add_plugins(DefaultPlugins.set(ImagePlugin::default_nearest()))
        .add_plugins(PixelCameraPlugin)
        .add_systems(Startup, setup)
        .run();
}

fn setup(
    mut commands: Commands,
    asset_server: Res<AssetServer>,
) {
    commands.spawn((
        Camera2dBundle::default(),
        PixelZoom::FitSize {
            width: 320,
            height: 180,
        },
        PixelViewport,
    ));

    commands.spawn(SpriteBundle {
        texture: asset_server.load("my-pixel-art-sprite.png"),
        sprite: Sprite {
            anchor: Anchor::BottomLeft,
            ..Default::default()
        },
        ..Default::default()
    });
}

A small example is included in the crate. Run it with:

cargo run --example flappin

Bevy versions supported

Migration guide: 0.4 to 0.5 (Bevy 0.10 to 0.11)

The PixelBorderPlugin has been deprecated. If you want a border around your virtual resolution, pass true to the set_viewport argument when creating the camera bundle (see example above).

Migration guide: 0.5 to 0.12 (Bevy 0.11 to 0.12)

The PixelCameraBundle has been deprecated. Replace it with a standard Camera2dBundle, to which you add the PixelZoom and PixelViewport components.

License

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

License: MIT OR Apache-2.0