Re: Does cocoa just leak?
Re: Does cocoa just leak?
- Subject: Re: Does cocoa just leak?
- From: John Hörnkvist <email@hidden>
- Date: Mon, 1 Oct 2001 02:40:45 +0200
On Sunday, September 30, 2001, at 10:07 PM, j o a r wrote:
On Sunday, September 30, 2001, at 08:34 , John Hvrnkvist wrote:
It's quite possible that NSBezierPath calls
"bezierPathByFlatteningPath" in that code and solves each generated
line segment for the point. Flattening will eat lots of memory for
complex paths.
This is what ObjectAlloc tells me about one of the allocations. It does
seem like it uses "bezierPathByFlatteningPath" - it seemed to me like a
class method to return a new path - that 's why I said it copied the
path. Perhaps it isn't so?
It flattens the path, and that means replacing any curve segment by a
lot of short lines.
You are absolutely right about it requiring a lot of resources though
John - is there an alternative way to obtain the x position on a path
given a known y-position? It takes way to long time as it is now. I was
never very good at math in school, mind you... ;)
Here is the fundamental formula:
<
http://www.bergen.org/AAST/Projects/3DSMaxTutorial/bezier_formula.gif>
and this picture illustrates the meaning:
<
http://www.bergen.org/AAST/Projects/3DSMaxTutorial/bezier_diagram1.gif>
You can iterate over the function until you find a point that matches
yours, or you can try to solve the equation for each line segment. You
should be able to make Newton-Raphson solve it, or you could solve the
cubic equation. Solving cubics is a bit messy; pick up a good math
reference book. (I like "Beta, Mathematics Handbook" by Lennart Rede and
Bertil Westergren. For those that happen to be in Sweden, it should be
available from your nearest university bookstore, eg Cremona at
Chalmers.)
Regards,
John Hornkvist
--
ToastedMarshmallow, the perfect Cocoa companion
http://www.toastedmarshmallow.com