[OpenJDK Rasterizer] Fwd: Re: Fwd: RFR: Marlin renderer #3

[Laurent Bourgès]

Jim,

I advocate I simply made a port of your FP approach in ShapeSpanIterator.c
without really understanding well the equations to adjust the edge to pixel
centers.
If there is a precision issue, it is also impacting the ShapeSpanIterator.c
!

Your recent proposal is very interesting (32.32 FP) as it could be
generalized to lineTo / curveTo in order to make all curve breaking
computations in 32.32 (long) maths ?

When I compared marlin vs ductus quality, small difference remain on lines
and I suspect it is related to the pen fitting. Do you know how to apply
the polygonal pen approach ( mentioned in graphics gem I ) ?
It seems a good method to ensure consistent line width based on adjusting
coordinates on the raster grid (24.8 FP).

I will make corrections soon and try your new approach asap (double + 32.32)

Moreover, could you explain me the dec/inc algo for quad/cubic curves ?
I found error= | dd (x,y) | / 8.

However the norm is not equal to max [ abs (ddx), abs (ddy) ]...
I now use squared norm check = ddx * ddx + ddy * ddy.

Thanks for all your advices,
Laurent
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