bevy_pixel_camera

A simple pixel-perfect camera plugin for Bevy, suitable for pixel-art.

This crates makes it possible to correctly display low-resolution 2d graphics with Bevy's default renderer and sprites.

While it is possible to achieve pixel-perfect rendering with Bevy's own camera and OrthographicProjection, doing so correctly requires to configure it in a specific way (you can't just use OrhtographicCameraBundle).

This plugin provides a camera which can be easily configured by specifying either the size of the virtual pixels, or the desired resolution.

Note that if either the width or the height of your sprite is not divisible by 2, you need to change the anchor of the sprite (which is at the center by default), or it will not be pixel aligned.

Also 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 set the default_sampler on the ImagePlugin:

    App::new()
        .add_plugins(DefaultPlugins.set(ImagePlugin::default_nearest()))
        ...

You can also ask the plugin to automatically set and resize the viewport of the camera. This way, if the window size is not an exact multiple of the virtual resolution, anything out of bounds will be hidden.

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

cargo run --example flappin

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:

• 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);
• probably more efficient (in most cases, the difference is probably negligible on modern computers).

Example code

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

fn main() {
    App::new()
        .add_plugins(DefaultPlugins.set(ImagePlugin::default_nearest()))
        .add_plugin(PixelCameraPlugin)
        .add_startup_system(setup)
        .run();
}

fn setup(
    mut commands: Commands,
    asset_server: Res<AssetServer>,
) {
    commands.spawn(PixelCameraBundle::from_resolution(320, 240, true));

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

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).

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