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alice-i-cecile
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Zeophlite
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Oct 8, 2026
Zeophlite
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Oct 8, 2026
There's almost certainly more we'll want on a point light, but this is the bare minimum we need to get something working with a reasonably sane API.
Not really needed yet, but might as well get all our patterns setup.
bevy_sprite_render does all our sprite rendering work, so it needs to be the one to consume bevy_sprite_light. This adds a top level flag for 2d lighting, so that it can remain opt in until it's at the point where we can start including it in our 2d profile.
Nothing sophisticated going on here yet, but it's a good starting point.
To avoid breaking every 2d game ever, we're keeping the brightness at full. This means users will need to turn down ambient light for lights to have an effect, but I think I'm okay with that (especially when compared to breaking everything is the alternative).
Because we don't need a different data shape (like a transform), we can just extract the main world type.
We're sticking with a uniform buffer for now, as it gets us WebGL2 support for free. Obviously it's nice to not have a limit imposed on us here, but in reality we'll likely need something more sophisticated than "one big storage buffer" to get decent performance with that many lights anyway. Happy to kick that down the road for now.
This gets a little bit messy with the feature flag, but should be something we can remove soon.
Our builtin 2d materials all go through the same mesh 2d pipeline, so it's mostly just a one line change (minus the shaderdef) to apply lighting to each one. Ambient light is already multiplied by it's brightness in the prepare step, so we can just multiply it by the output color directly.
Now that the pieces are in place, let's render some lights. Nothing too crazy here. For each vertex, check if we're in range of each light. If we are, add in the amount of light, using the attenuation formula. I used this same formula in bevy_light_2d, and have been pretty happy with how it works. Though adding it back in made me realize we need to have a falloff setting on the light itself.
This adds a level of customization to lights that really lets you make them your own. We changed from a Vec4 to Vec3 on our color to keep everything within 32 bytes. We weren't using the alpha on the color, so no harm done.
This color was changed so it's not really final. Renamed to output_color to match how the sprite and material shaders work.
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Objective
This PR aims to showcase what the first step of first-party 2d lighting in Bevy could look like. This initial version adds 2d ambient light and 2d point lights.
While the solution is complete and usable, it's not (at this stage at least) intended as a merge candidate, but rather to help bring to life the approach outlined in the design doc.
Solution
For a full rundown, see the design doc on hackmd.
Testing
Lighting can be tested with the new 2d lighting example:
Showcase
2026-10-07.11-41-08.mp4
Claude Code was used in the research phase, specifically to compare and contrast a lot of the prior art that exists, and how they do or don't support the design goals outlined in the above document. The code was written by me, with some assistance from Claude Code, most notably to help put together the example. Documentation was written by me (with some of it lifted from how I originally wrote it in bevy_light_2d).