Hi again. I found an implementation of a closed form cubic root solver (from graphics gems): http://read.pudn.com/downloads21/sourcecode/graph/71499/gems/Roots3And4.c__.htm
I did some micro benchmarks, and it's about 25% slower than the one I have. I'm thinking we should use it anyway because it's much better in every other way: it finds all roots, it doesn't make its callers give it a root array that is longer than the total number of roots, and most importantly, it doesn't fail because of an iteration upper bound. From my testing, I noticed that this happens too frequently for comfort in my cubicRootsInAB. I haven't noticed any rendering artifacts caused by this, but I also haven't tried rendering every possible curve and it's better to prevent bugs than fix them. What do you think? Regards, Denis.
