Re: performance of NSBezierPath
Re: performance of NSBezierPath
- Subject: Re: performance of NSBezierPath
- From: "John C. Randolph" <email@hidden>
- Date: Mon, 8 Apr 2002 14:24:31 -0700
The cost of drawing an NSBezierPath is a function of the number
of times it intersects itself. In the case you describe, you
might want to simply call [NSBezierPath
strokeLineFromPoint:toPoint:], and not worry about getting
strictly correct anti-aliased intersections.
A few weeks back, someone on the CG team explained to me that:
"Drawing 1000 individual moveto/lineto segments is essentially
equivalent to drawing 1000 independent thin rectangles of
various lengths at various orientations. Drawing a 1000 segment
connected/stroked path with round linejoins involves parallel
curve formation (including arc line joins), flattening the
curves, feeding the entire beast to the scan converter as a
huge self-intersecting polygon, resolving the self-intersections
to get the antialiasing right, etc...."
-jcr
On Sunday, April 7, 2002, at 08:30 AM, ruediger schmidt wrote:
Hi,
just tested the performance of NSBezierPath because I'm
thinking about a
graphic app where polygons with a lot of points ( up to 20000 )
will be common.
I did the testing with a NSBezierPaths with random points in
the rang 0,200,0,300.
For paths with more then 1500 I had to wait more then 1 minute
(G4, 400 MHz) and
even on a new dual G4 it was slow.
My question is: Did some one else had same results? Is there a
pitfall witch causes
this poor performance? Is there a easy way to improve
performance significantly beside using OpenGL witch gives good
results?
If it's not my fault is there a chance that apple will fix this (bug)?
thanks
ruediger
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John C. Randolph <email@hidden> (408) 974-8819
Sr. Cocoa Software Engineer,
Apple Worldwide Developer Relations
http://developer.apple.com/cocoa/index.html
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