[OpenJDK 2D-Dev] Rotation per-pixel accuracy

Jim Graham Jim.A.Graham at Sun.COM
Fri Jun 6 20:38:41 UTC 2008

Good to hear it as it avoids some hard decisions.

Per-pixel consistency is always the desired goal, but sometimes you have 
to look at what is possible to accomplish with the APIs we depend on and 
make some hard decisions.  If it would take a "work around" technique 
that would take 100x as long in order to get per-pixel accuracy we start 
looking the other way, when it takes only 20% longer, we usually go for 
it and somewhere in between is a line we've never really drawn very well.

And then there is always the possibility that a fresh approach will 
discover a new way to get per-pixel accuracy without any performance 
hits and so we sometimes stall on the hard question waiting for someone 
to have a flash of inspiration.  :-(

So, all in all, good to hear that we don't have to make a decision 
here... ;-)


Clemens Eisserer wrote:
> Hi again,
>> Are there rules that rendering has to be per-pixel consistent, with
>> what should I compare to see wether my implementation works correct?
> Sorry about the traffic ... it seems different rounding errors were
> the cause for the different results,
> the rotated text was drawn to the BI at the position 0/20, whereas it
> was rendered at 100/100 to screen.
> With adjusted positions I get consistent rendering with rotation also.
> Sorry for the traffic :-/
> Thanks, Clemens

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