I ended up going with:
- get rid of edgeMxy in all methods but addLine()
- addLine computes min/max of first/lastScanline
- addLine also computes min/max of x1,x2 values
this turned out to be just about the same speed for my FX rendering
version (which I believe is more sensitive than the way it is integrated
into JDK, so it should be even less noticeable in JDK). It also paved
the way for a couple of other optimizations that ended up netting about
1FPS for my current test case that I use so I'm happy for now.
The code is a lot simpler now...
...jim
On 11/9/2010 3:26 PM, Denis Lila wrote:
Hi again.
I just thought of this: if we're really concerned about the accuracy
of the edgeMinX edgeMaxX variables, we could find the curves'
critical points and use them to compute the min/max X values. After all,
we're creating (or rather "setting") the Curve objects anyway. This isn't
as fast as using the bounding boxes, but it's close and much more accurate.
Regards,
Denis.
----- "Denis Lila"<dl...@redhat.com> wrote:
Hi Jim.
All lines generated from a given "allegedly monotonic" curve are
recorded with the same "or" (orientation) value. But, if the curves
are not truly monotonic then it might be theoretically possible to
generate a line that is backwards with respect to the expected
orientation. It
would then get recorded in the edges array with the wrong
orientation
and slope and then rasterization might unravel.
I see. In that case, I think it's a good idea if we don't make curves
"monotonic". I already did this, by moving the edgeMin/axX/Y handling
and orientation computations in addLine. This did make it slower
compared
to the file you sent me, but only by very, very little. Curves were
affected the most, and they were only 1% slower. I think we can handle
this, especially since lines were about 1% faster. The code is also 70
lines shorter.
The edgeM* members are used only so we don't have to iterate through
every
scanline if this is not necessary, and so that we can tell PiscesCache
that the bounding box is smaller than what Renderer is given. However,
now
that we keep the bucket list, I think it would be more efficient if we
got rid if EdgeM[in|ax]Y and simply computed the y bounds by looking
at the
head and tail of the bucket list.
Also, perhaps we can keep track of edgeM[in|ax]X using the bounding
boxes
of curves, instead of the lines in the flattened curves. This would
not
be accurate, but I don't think it would affect rendering. It would
simply
result in a few more alpha boxes than necessary. I don't think these
would
be too bad, because mostly they're just going to be all 0 so they will
be skipped because getTypicalAlpha() is now implemented.
How do you think we should handle these 4 variables?
Thank you,
Denis.
----- "Jim Graham"<james.gra...@oracle.com> wrote:
Hi Denis,
On 11/8/2010 2:39 PM, Denis Lila wrote:
Finally, I discovered (while testing for other problems) that the
curves are not truly monotonic after slicing them. I realized
this
years ago
when I was writing my Area code (see sun.awt.geom.Curve) and put
in
tweaking code to make them monotonic after they were split. They
are
never off by more than a few bits, but you can't trust the curve
splitting math to generate purely monotonic segments based on a t
generated by some unrelated math. Sometimes the truly horizontal
or
vertical t value requires more precision than a float (or even a
double) can provide and splitting at the highest representable
float less than
the t value produces a pair of curves on one side of the hill and
splitting at the next float value (which is greater than the true
t
value) produces curves on the other side of the hill. Also, when
the
curve has been split a few times already, the t values loose
accuracy
with each split. This will all be moot if I can eliminate the
splitting code from the renderer, but it may also play a factor
in
the
stroke/dash
code...
Making curves monotonic is only used for optimization purposes,
so it can't see how it would affect rendering correctness.
Fortunately, the non-monotonicity is limited to a few bits of
precision
so this may never generate an errant edge in practice unless
flattening
gets really fine-grained...
...jim
