   Selecting a circle in a grid/2d array?
  I'm trying to select all the points (say 3 points away) in a circle around a specific point.I am working on a simple terrain editor to raise/lower heights, but right now when I raise/lower,I do it based on the distance away from the point clicked(so farther the distance from the clicked point, the less the vertex is moved), but I am not sure how to select all the vertex's around my point in a circular pattern.To show an example(although this is more of a diamond shape than a circle- can't even figure that out :-/ )0123456789101112131415161718192021 22 23242526272829 30 31 32 3334353637 38 39 40 41 42 4344454647 48 49 50 51525354555657 58 59606162636465666768697071727374757677787980   
.;  Thanks! I know it's something I should have remembered, but for the life of me couldn't!Thanks!   