Krita to Bevy animation workflow

Goal: 1-click in Krita, see animation in game within seconds (milliseconds?)

I tried to find a nice way to export krita animations to something Bevy would accept, but couldn't find any, this is what I've got so far.

Status

Work in progress!

The workflow... works, but there are a few manual steps left

• make bevy_krita_anim able to watch itself, so we don't need watchexec
• support for bevy_trickfilm animation manifest format?
• support for multi-row atlases

Prerequisites

• Krita 5+
• cargo

Preparation

Install the atlas baking tool from this repository:

cargo install --git https://github.com/johanhelsing/krita_bevy_anim

Install watchexec-cli so we can trigger baking automatically after rendering:

cargo install watchexec-cli

Create an empty render folder

mkdir -p /path/to/render

Watch for renders appearing here:

cd /path/to/render
watchexec -e png "krita_bevy_anim . --rm --output /path/to/game/assets/your_anim"

This will watch for new images appearing in the render folder and

Let this run in the background while you work in Krita

Workflow

1. Make an animation

Make an animation with Krita, using animation tools with dope sheet, onion skinning etc.

2. Render the animation

Hit File -> Render Animation

• Choose "Image sequence"
• Set the location to the empty render folder you created earlier
• Leave "base name" empty (required, for now at least)
• Choose "Only render unique frames"

Don't worry, Krita will remember these settings. Next time you'll only need to hit render and ok.

...or bind the "Render Animation Again" action to a keyboard shortcut through the Krita settings.

Using the assets in your game

Our watcher script will detect the render and create some new files in your assets folder:

• your_anim.png: All the unique sprites baked into one texture
• your_anim.titan: Manifest file containing details about how the atlas is partitioned.
• your_anim.flippy: A file containing frame timing

1. Add bevy_titan plugin

Add bevy_titan to your game's dependencies and add its SpriteSheetLoaderPlugin. This is a tiny plugin that adds support for the .titan sprite sheet manifest, we generated earlier, which we're using to communicate grid size and dimensions to Bevy.

2. Load the .titan file

let anim_atlas: Handle<TextureAtlas> = asset_server.load("your_anim.titan");

TODO: explain how to use timings file.

3. Enable asset hot reloading

Read bevy docs for how.

You should now be good to go, for subsequent updates, simply leave your game running, then:

1. render the animation
2. run the baking command

And you should see your updated animation.

The solutions I didn't like

https://github.com/Falano/kritaSpritesheetManager only supports fixed intervals, meaning your sprite sheets will have to run at a homogenous speed, meaning you will can't time animations as you want, or you'll have to choose a really high speed and have lots of wasted identical frames.

Another issue with it, is that it seems to bake the onion skinning trails into the actual sprites, so you'll have a lot of green and red in your game unless you remember to turn that off before exporting.