Aleksei, If you relax the condition, you increase the number of splits. Normally, making such a change is a mistake because the benefit of simplifying the condition is easily outweighed by the greater cost of increasing the recursive depth. This is the very reason why we ended up with a much more complex set of conditions than in earlier version of FT: it reduces the number of splits very significantly.
I've just had a brief chance to look at your proposal, and I now understand why it makes no difference to the output. The chances of your relaxed condition causing a split when the current (theoretically correct) condition doesn't is very small: a control point would have to be in the small white areas in the bottom corners of the rectangle in your diagram. Note that this check is only made after subdivisions for the distance from the chord. Since this is the most expensive test, it is done last, and normally only once. Since there is no performance improvement, I don't believe that your proposal should be included in the code. It would make the code more opaque: It is obvious why the current code [if P1 or P2 is outside P0-P3, split the curve] does what it does (especially if reference is made to Hain's paper); it would not be at all clear why your condition for splitting [if P1 or P2 is far from the center of P0-P3, split the curve] was there. If you do come up with an improvement to the algorithm that is significantly faster (and still provably correct), then by all means submit it for review (but don't expect a quick or uncritical response). Thanks. David %^> -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of ??????? ????????????? Sent: 11 November 2010 20:23 To: GRAHAM ASHER Cc: freetype-devel Subject: Re: [ft-devel] cubic clean up Shaded areas "Before" and "After" in the attached figures show where control points have should be to permit flattening. Is this a risky change? If anything, it is slightly more conservative, yet the conditional is quite a bit simpler. _______________________________________________ Freetype-devel mailing list [email protected] http://lists.nongnu.org/mailman/listinfo/freetype-devel
