# [OpenJDK 2D-Dev] X11 uniform scaled wide lines and dashed lines; STROKE_CONTROL in Pisces

Denis Lila dlila at redhat.com
Wed Oct 20 07:54:52 PDT 2010

```Hi Jim.

> I wasn't sure why you isolated that term out there instead of just
> grouping it with the rest of the numerator - is there a danger of
> overflow if you multiply it before you do the division?  If so, then
> that is fine since it doesn't actually affect the number of fp ops so
> it should be the same performance.

I'm not sure if there's a danger of overflow, but the numbers there do
tend to be large, so I wanted to be safe.

> In #2, you have a bunch of "I'() || B'()" which I read as "the slope
> of the derivative (i.e. acceleration) is equal", don't you really mean
> "I() || B()" which would mean the original curves should be parallel?
> Otherwise you could say "I'() == B'()", but I think you want to show
> parallels because that shows how you can use the dxy1,dxy4 values as
> the parallel equivalents.

Not really. I've updated the comment explaining what || does, and
it should be clearer now. Basically, A(t) || B(t) means that vectors
A(t) and B(t) are parallel (i.e. A(t) = c*B(t), for some nonzero t),
not that curves A and B are parallel at t.

> so it works out the same either way.  Fun...

Yeah - if one is consistent with one's definitions and if the algebra
is followed mechanically the signs take care of themselves.

> No, the existing stuff is clean and works fine so let's leave it - for
> now at the very least...

Sure. I just meant that when I have some free time in the future I'll
implement this other idea just to satisfy my curiosity. I doubt it
will work better than what we have though (or work at all).

Regards,
Denis.

```

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