I'm wondering how to achieve a neon-light type effect. For example, in Pac-Man Chamipnship Edition:
Or in Geometry Wars:
Is that a Bloom Effect? Or what techniques would I have to look for?
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Here you go :)
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.
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:
(SRC_COLOUR * SRC_ALPHA) + (DST_COLOUR * ONE)
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.