Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!bloom-beacon!oberon!sdcrdcf!trwrb!cadovax!gryphon!richard
From: richard@gryphon.CTS.COM (Richard Sexton)
Newsgroups: comp.sys.amiga.tech
Subject: Rotating Rectangles, was (Re: IFF format for 2D CAD)
Summary: OIC, but I don't agree
Message-ID: <4096@gryphon.CTS.COM>
Date: 19 May 88 19:03:08 GMT
References: <4071@gryphon.CTS.COM> <YWYRI-y00VAAA-Dlgc@andrew.cmu.edu>
Reply-To: richard@gryphon.CTS.COM (Richard Sexton)
Organization: Trailing Edge Technology, Redondo Beach, CA
Lines: 36
Posted: Thu May 19 12:03:08 1988

In article <YWYRI-y00VAAA-Dlgc@andrew.cmu.edu> mp1u+@andrew.cmu.edu (Michael Portuesi) writes:
>Richard Sexton expresses the following question:
>>
>> Huh ?
>
>Imagine you have a rectangle defined by its top/left and bottom/right
>corner points:
>
>	    +------
>	    |     |
>	    ------+
>
>You rotate an object by rotating its points:
>
>		   /\
>	          /  +
>		 /  /
>		+  /
>		 \/
>

Hmm. Okay. You are rotating all four points to generate the rotated rectangle.

I still maintain that rectangles are most efficiantly represented with
top left and bottom right points. It saves space in the display list and
saves transmission time to a rendering host, if there is one.

If you can compute the rotated points, shirley you can compute the "missing"
vertices.

If you cant, write me, I think I have the algorithm somewhere.......


-- 
           Have a nice day or Klortho will rip your nuts off.
richard@gryphon.CTS.COM                          rutgers!marque!gryphon!richard