Hang on - what about the other blobs?
The cool thing about this effect is the way that the blobs interact with eachother; joining and splitting apart! How do we mix the values together?
The answer is straightforwards - calculate a distance2 value for EVERY blob and multiply them together to get the final value you then convert to a pixel brightness.
To understand this we need to think of a number of specific cases. I hope that what I say is clear enough...
- Near, or very near to the centre of a blob: the distance squared will be 0 - or very close to it - and anything that is multiplied by this will become 0 too. Therefore points that are very close to the centre of a blob will always be bright.
- Far away from any blobs: the distance squared will be very large, and as we multiply it again and again it will only be getting bigger and thus darker.
- Just outside one blob but not near any others: the distance might be fairly small, but because it is a long way from any others their large distance2 values will soon make it too large and thus dark.
- Just outside one blob which is very close to another blob: the distances will be fairly small in all cases meaning that the multiplied value will grow slowly and still be fairly bright.