I'm wondering how to achieve a neon-light type effect. For example, in Pac-Man Chamipnship Edition:

PacMan CE

Or in Geometry Wars:

Geometry Wars

Is that a Bloom Effect? Or what techniques would I have to look for?

  • 1
    \$\begingroup\$ There is a great bloom effects tutorial here \$\endgroup\$
    – bobobobo
    Mar 23, 2013 at 23:55

3 Answers 3


Here you go :)

GPU Gems - Glow Effect

With that many entities with a glowing effect on the screen (especially in Geometry Wars), it's more often than not a shader effect that's similar to the shader described in that paper.

  • \$\begingroup\$ This came up in moderation due to a suggested edit for a broken link. While I recognize this answer is old, there's still a policy discouraging link-only answers. Would you consider summarizing the basic approach in the body of this answer, rather than leaving it entirely up to the external resource? In case the link breaks again in future, it would be ideal to have the key points preserved here. \$\endgroup\$
    – DMGregory
    May 26, 2017 at 4:09

You may not even need a full-screen bloom/glow effect (remember that this sort of effect is quite GPU-intensive, particularly if you're making a 2D game and want to avoid high system requirements)

First, try just rendering your sprites with additive blending - with a blending equation such as:


Then bake the glows into your sprites (or render them as additional additive sprites - to create a 'glow sprite', just blur your original sprite using a gaussian blur filter in whatever paint package you use)

Of course, this approach has some limitations - the adding-up of overlapping sprites may be undesirable, and would be avoided by using a full-screen bloom/glow effect


There are two ways of achieving this;

The top one (at a guess) just uses semi-transparent images.

The bottom one more complicated (again a guess) plays with buffers to create the glow (bloom) effect.


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