bevy_fast_light 0.10.0

# Bevy Fast Light

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Simple 2D lighting for Bevy focused on performance over features.

:warning: | This is still in development and not at all feature complete.

## Features

### Lights

| Purpose       | Component        | Config                  |
| ------------- | ---------------- | ----------------------- |
| Ambient light | `AmbientLight2d` | `color` and `intensity` |
| Mesh light    | `MeshLight`      | `color`, `intensity`    |

### Occluders

| Purpose       | Component      |
| ------------- | -------------- |
| Mesh occluder | `MeshOccluder` |

`Sprites` are rendered above occluders if they are on the same or a higher z-level. Also see [Showcase](#showcase).

### Mesh2d

The following `Components` allow the customization of their shape via attaching a `Mesh2d`:

- `MeshLight`
- `MeshOccluder`

The `Mesh2d` is required for the `Components` to render.

## Limitations

- There is currently no shadow casting for light occluders.

## Usage

Take a look at [`/examples`](https://github.com/leomeinel/bevy_fast_light/tree/main/examples) to find out how to use this crate.

### Showcase

I am using most features in my learning project [Slimy Mist](https://github.com/leomeinel/slimy_mist) and have also successfully implemented a day/night cycle.

This also visualizes how `Sprites` are rendered above occluders if they are on the same or a higher z-level.

<img src="https://github.com/leomeinel/bevy_fast_light/blob/main/static/slimy_mist.webp?raw=true" width="400" alt="slimy mist example">

### Examples

#### `ambient_light.rs`

Scene with a light sky colored `AmbientLight2d` with a lower `intensity`, a green `Rectangle` as background and an amber `MeshLight`.

<img src="https://github.com/leomeinel/bevy_fast_light/blob/main/static/ambient_light.webp?raw=true" width="400" alt="ambient light example">

#### `mesh_light.rs`

Scene with a green `Rectangle` as background and an amber `MeshLight`.

<img src="https://github.com/leomeinel/bevy_fast_light/blob/main/static/mesh_light.webp?raw=true" width="400" alt="mesh light example">
    
#### `mesh_occluder.rs`

Scene with a light sky colored `AmbientLight2d` with a lower `intensity`, a green `Rectangle` as background, an amber `MeshLight` and a `MeshOccluder`.

<img src="https://github.com/leomeinel/bevy_fast_light/blob/main/static/mesh_occluder.webp?raw=true" width="400" alt="mesh occluder example">

## Alternatives

- [bevy_firefly](https://crates.io/crates/bevy_firefly)
- [bevy_2d_screen_space_lightmaps](https://crates.io/crates/bevy_2d_screen_space_lightmaps)
- [bevy_light_2d](https://crates.io/crates/bevy_light_2d)
- [bevy_lit](https://crates.io/crates/bevy_lit)

## Resources

### Code

- [Bevy Example - Custom Post Processing](https://bevy.org/examples/shaders/custom-post-processing/)
- [Bevy Example - Custom Render Phase](https://bevy.org/examples/shaders/custom-render-phase/)

### Articles

- [hackmd.io - Bevy's Rendering Crates](https://hackmd.io/@bevy/rendering_summary)
- [hackmd.io - The Abyss](https://hackmd.io/@bevy/the_abyss)
- [slembcke.net - 2D Lighting Techniques](https://www.slembcke.net/blog/2DLightingTechniques/)
- [slembcke.net - 2D Lighting with Hard Shadows](https://www.slembcke.net/blog/SuperFastHardShadows/)
- [WebGPU Shading Language](https://www.w3.org/TR/WGSL/)