halo: you have to copy the scene to a texture then multiply blend it a few tines to make only the bright parts to stay (you can use alpha also to regulate the initial darknes), then blur the texture (using additive blending) with few passes to make the glow bleed from the edges... then additive blend with the scene.
napoleOn: you can't really compare my code for filax's code because you should have same amount of passes and same texture size to compare. (not saying mine isn't slower... because it's far from optimised)
napoleOn: you can't really compare my code for filax's code because you should have same amount of passes and same texture size to compare. (not saying mine isn't slower... because it's far from optimised)