Am 29.11.16 um 01:09 schrieb Jim Graham:
With respect to float/double, I have another bug somewhere where we
have a large inaccuracy for a very large circle that intersects the
viewing area along only a very tiny portion. The errors get
especially bad with dashing because we iterate each dash using an
incrementally relative sub-divide rather than returning always to the
original curve to sub-divide from t1-to-t2. I'll look it up and send
you a pointer so you can see how Marlin does with those paths. I
believe that I briefly modified the Pisces Dasher to simply use
doubles and the problem went away, but I didn't do any performance
analysis and the newly accurate dashes no longer matched the
still-float-based fills so more work was needed. Modern processors
tend to deal with double precision natively and so other than storage
considerations double calculations are often as fast or sometimes
faster than float (because of not needing to be cast back to 32-bit
float when the FPU always produces 64-bit double answers)...
I can help you out here because I have reported these bugs. The
references are
https://bugs.openjdk.java.net/browse/JDK-8160599
https://bugs.openjdk.java.net/browse/JDK-8160600
I also think that using doubles instead of floats would make things much
more accurate
especially as the user actually can expect that because the JavaFX API
also uses doubles
and it is not clear to the user that this is currently reduced
internally to float.
Michael
