Don't confuse this with meat balls, this has absolutely nothing to do with it! My friend Garry Williams posted this video on Youtube. These are meta-balls he computed in real time:

Meta balls in 2D are quite simple. Take an image. Each of you meta balls emit a field, the closer you are from the emitter, the stronger is the field. Then, your color each pixel depending on the value of field at that position. The field doesn't necessarily describe a circle, it can be elipses or anything. Anyway, it can look like that:

2D Meta Balls

Is this case, pixels are colored in black where the field is the strongest and uses gradients of orange and yellow for the other values. So when these shapes move around and meet, they seem to "merge" in an hypnotic lava lamp effect!

Well that's pretty easy in 2D space, because you're computing your values in a discrete finite domain. But how do you do that in 3D space, where the values are in a continuous domain? Well you have make it discrete. And then use voxels (volumetric pixels) and find a way to render them, which is not trivial (our GPUs only know how to render triangles).

Any questions? Wanna know more? Well ask Garry! Hahaha, just kidding, ask your questions in the comments.

Note that this is work in progress.
Garry's meta-balls project page.
Download the application.
Download the source code.