87 lines
3.7 KiB
Text
87 lines
3.7 KiB
Text
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From fatcity!root@news.cts.com Mon Apr 20 10:54:32 1998
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["2073" "Mon" "20" "April" "1998" "07:50:34" "-0800" "Steve Baker" "sbaker@link.com" nil "54" "Re: How To Q: Off-screen object culling." "^From:" nil nil "4" nil nil nil nil nil]
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X-Comment: OpenGL Game Developers Mailing List
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Organization: Fat City Network Services, San Diego, California
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From: Steve Baker <sbaker@link.com>
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Sender: root@fatcity.com
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To: Multiple recipients of list OPENGL-GAMEDEV-L <OPENGL-GAMEDEV-L@fatcity.com>
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Subject: Re: How To Q: Off-screen object culling.
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Date: Mon, 20 Apr 1998 07:50:34 -0800
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On Sat, 18 Apr 1998, Jason Maskell wrote:
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> This is probably an FAQ, but I'm to the point now where I need to be
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> able to tell when one of my objects is offscreen and not even send it
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> down the pipe. This would be pretty simple if I was using glFrustum,
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> but I'm not at the moment. I could switch, but I haven't quite got my
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> head around how to get the same results as I get using glPerspective..
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> If someone can point me to some code that does some simple pre-culling,
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> I would be most grateful.. >
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Well, if you can do it with glFrustum then you can do it with
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gluPerspective. Note that gluPerspective simply calls glFrustum.
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It's like this:
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void APIENTRY gluPerspective( GLdouble fovy, GLdouble aspect,
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GLdouble zNear, GLdouble zFar )
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{
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GLdouble xmin, xmax, ymin, ymax;
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ymax = zNear * tan( fovy * M_PI / 360.0 );
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ymin = -ymax;
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xmin = ymin * aspect;
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xmax = ymax * aspect;
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glFrustum( xmin, xmax, ymin, ymax, zNear, zFar );
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}
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[This is actually the source code for gluPerspective from the Mesa
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library - but since it only involves regular OpenGL API, it should
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work on any OpenGL implementation]
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> BTW, I've bought the red book finally...
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Always a good move. I have yet to hear anyone who regretted it.
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Steve Baker (817)619-8776 (Vox/Vox-Mail)
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Raytheon Systems Inc. (817)619-4028 (Fax)
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Work: SBaker@link.com http://www.hti.com
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Home: SJBaker1@airmail.net http://web2.airmail.net/sjbaker1
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--
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Author: Steve Baker
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INET: sbaker@link.com
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Fat City Network Services -- (619) 538-5051 FAX: (619) 538-5051
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San Diego, California -- Public Internet access / Mailing Lists
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