Some reference pics :
And more reflective:
Any ideas? My initial thought was particles, but it seems they would be too detailed and involved for a particle renderer. Would it be better to use a mesh with shaders? How would you get the "shimmering" effect often seen in moving bubbles?
Yeah. A mesh with shaders is definitely the way to go. Check out this link and this one for some shaders that might be a good starting point. Although, on second thought, you might create a bubble image and put that on a particle system. That probably won't give the effect you're looking for, though. Hope this helps?
It depends on the level of detail, vs. the number of bubbles you want. If you actually want to be able to have bubbles which look similar to your pictures (i.e. fairly large on screen, with a reflection), you'll need to use a mesh and a shader which gives you a reflection. You'd then need to render a "cubemap" to act as the reflection, which should be a decent approximation of the scene within which the bubble will be.
Then you'll need to use a shader which supports both transparency and cubemap reflections. None of the built-in shaders do this, but this "Window Shader" on the Wiki looks just the job!
However, if you want quantity rather than quality, you could use a static image with a particle system, making sure that your image uses transparency to make the bubbles partially see-through. Here are some examples of transparent bubble images that you could use: http://dirt2.com/resources/spheric-bubble-gem-clip-art/
Enjoy :)
did you find any reflective transparent shaders?
getting some blue red green color shaders to twirl on it too would be good.