OK, so for example, if I need some glowing splashes on the box, I need to pain those splashes on the texture, and then, make then black on the alpha channel?
I'm not 100% sure what you mean but I think you understood it right
It's simple: full alpha = now glow, no alpha = max glow
in gimp for example I would create a new, transparent layer (which will be the glow mask), paint the parts which should be illuminated and the use selection from alpha.
Now you just have to select the base layer and hit 'del' to delete the selected parts. These will glow then
Of course it is important that the file format supports alpha.
@ratchet thanks for the kind words
I'll try to make a simple (but similar) bloom-shader for you
With this the glow effect should look nice.
It's so usefull for ancient magic, futurist things and levels or simply to make some retro glowing games.
The main idea of bloom is using it on the whole scene, not just specific parts like glowing stripes
With this all bright areas of the screen will look bright - and this makes the whole scene seem more realistic.
For my bloom shader I tried to make the effect intensive and noticable but still smooth, so without having a brightness overkill