Emissive and bloom
Make bright things look bright by letting their light spill over.
Try it
Try to read the signs through this fog. Press TUse the switch to raise the bloom threshold so only the neon glows, then drag the sliders to tune it.
Why it matters
A screen cannot show real brightness, so games fake it. Emissive materials glow on their own, and bloom takes the brightest parts of the image, blurs them and adds them back on top, the way a camera lens or your eye would. It is what makes neon, magic and pickups feel like light sources. The threshold matters most: bloom only the brightest things, or the whole image turns to fog. This demo measures real pixel brightness from 0 to 1, because a web canvas stops at 1. A game engine usually works in HDR, where emissive colours go above 1, so its threshold of about 1 means the same thing.
Where it's used
- Sci-fi and neon: signs, lasers and screens
- Pickups: draw the eye to what matters
- Magic and explosions: the flash that sells the hit
- Arcade games: glowing shapes on black
- Sunlight: a soft glow around bright windows
Add it to your game
How to spot it in your own game: Your whole picture looks hazy and text smears, or bright things glow no more than anything else, so turn bloom off to compare, then raise its threshold and lower its strength.
Paste this into your AI coding tool. It works for 2D or 3D in any engine (Unity, Unreal, Godot, web). Use Quick for a fast fix, or Detailed when you want it done properly.
Add bloom: render in HDR with emissive materials above 1.0, keep only pixels above a threshold of about 1.0, blur them through a chain of smaller and smaller copies, and add the result back at a strength of about 0.1 to 0.3.
Add emissive materials and bloom (Unity Volume Bloom, Unreal Post Process Bloom, Godot WorldEnvironment Glow, or a canvas with downscaled copies). Render to an HDR target if you can, and give glowing things emissive values above 1.0 so only they pass the threshold. Extract pixels above the threshold (start around 1.0) with a soft knee, then blur by repeatedly halving the image and scaling back up, which is far cheaper and smoother than one big blur. Add the result on top of the scene at a low strength (0.1 to 0.3), and tone map afterwards. Mark what should glow on purpose: pickups, magic, screens and neon, not the sky or white walls. Expose threshold, strength and radius as settings, and give players a way to reduce bloom, because too much hurts readability and comfort.
Is it built into your engine?
| Unity | Built in: Bloom Volume Override (URP and HDRP), Lit shader EmissionAdd Bloom to a Volume and set Threshold and Intensity with an emissive material, while the deprecated Built-in Render Pipeline needs the Post Processing package. |
|---|---|
| Unreal | Built in: Bloom post process, Emissive Color inputBloom is on by default so bright emissive materials glow, and you tune its intensity and threshold in a Post Process Volume. |
| Godot | Built in: Environment glow, BaseMaterial3D emissionEnable glow in the Environment, set HDR Threshold and give materials emission, though the Compatibility renderer has fewer glow options and 2D glow there needs Canvas background mode. |
Checked against Unity 6.6, Unreal Engine 5.8 and Godot 4.7 official docs, November 2026.
Common mistakes
A threshold so low everything glows and the image goes foggy, strength turned up until nothing is readable, blooming the whole UI so text smears, and using one large blur that is slow and shows visible banding.
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