HDTenEightyP/NetNews huggingface dataset:
From: pff@pablo.b11.ingr.com (Pablo Fernicola)
Subject: Re: Determining if a polygon is convex
Keywords: polygon, convex, area
Organization: Intergraph Corp. Huntsville, AL
Distribution: usa
Date: Wed, 14 Oct 1992 20:49:21 GMT

Walk through all the vertices, taking the cross product between 
the vectors that form the two adjacent edges.  If at any time the 
normal (resulting from the cross product) "flips", pointing in the 
opposite direction of the previous normal, the polygon is not convex.  
As an added bonus, you can use the normal for your face culling too.

-Pablo
------------------------------------------------------------------------------
| Pablo Fernicola	 |                                                   |
| Proprietary Graphics	 |    clip, clip, clip;                              |
| pff@pablo.b11.ingr.com |        render that span                           |
|    			 |    clip, clip, clip;                              |
| (205) 730-4173 (voice) |        your Z has gone too far                    |
------------------------------------------------------------------------------

Newsgroups: comp.graphics
From: hollasch@kpc.com (Steve Hollasch)
Subject: Re: Determining if a polygon is convex
Summary: Ooops, I goofed.
Organization: Kubota Pacific Computer, Inc.
Date: Wed, 14 Oct 1992 17:38:16 GMT

zhu@sgi.com (Benjamin Zhu) writes:
| (2) Walk along the edges. See if every other vertex lies at the
|     same side of current edge. If so, convex. Otherwise, not!

hollasch@kpc.com (Steve Hollasch) writes:
| 
|     This fails for the following polygon:
| 
|                3 ________ 2
|                  \       |         Another way to think of this rule
|                   \   5  |         is that you're always making a left
|                    \ /|  |         turn to get to the next vertex.
|                     X |  |         It's the self-intersection that
|                    / \|  |         screws us up here.
|                   /   4  |
|                  /       |
|                0 ~~~~~~~~ 1

    Sorry Benjamin, I goofed here.  I thought you were testing against only
the successive vertex, not every other vertex as you stated.  This method
should work.

    By the way, it seems that for a polygon with N edges, you'd only need to
test edges 1 through N-1 (you wouldn't need to test the last edge).
However, this method appears to be O(N^2).  Is there another, more efficient
approach in the general case?

______________________________________________________________________________
Steve Hollasch                                   Kubota Pacific Computer, Inc.
hollasch@kpc.com                                 Santa Clara, California
Newsgroups: comp.graphics
From: tlhouse@nyx.cs.du.edu (Thomas House)
Subject: Re: Blue screen image processing
X-Disclaimer: Nyx is a public access Unix system run by the University
	of Denver for the Denver community.  The University has neither
	control over nor responsibility for the opinions of users.
Organization: Nyx, Public Access Unix at U. of Denver Math/CS dept.
Date: Sat, 10 Oct 92 01:39:00 GMT


The program referred to (ZSoft Paintsomethingorother) is PhotoFinish ..
its a stripped down version of its big brother, Publishers PaintBrush ..
both run under MSWindows 3.x, both are pretty well loaded with features
(comparatively speaking, anyway) ..
From: Hoenie.Luk@f217.n914.z8.rbbs-net.ORG (Hoenie Luk)
Newsgroups: comp.graphics
Subject: Vpic and .tga
Date: 15 Oct 92 09:19:00 GMT

Hi all:

        VPIC 4.9 to 5.1 does not seem to be able to change the  
brightness, contrast and color of a 32k-color .tga.  Is it supposed to  
be that way?  Or is there something wrong with my Orchid Fahrenheit 1280  
video adaptor?

.............Hoenie

---
 * SLMR 2.1a * Press any key to continue or any other key to quit


 * Origin: The PC GFX Exchange * 415-337-5416 HST/V.32 * (8:914/217.0)
Newsgroups: comp.graphics
From: nino@vmars.tuwien.ac.at (Marinos Yannikos)
Subject: Re: Public domain Raytracing programs
Organization: TU Wien, Vienna, Austria
Date: Thu, 8 Oct 1992 15:15:18 GMT

mike@htsmm1.Las-Vegas.NV.US (Mike Haaland) writes:
: Renee.Teunissen@freudsys.nl.mugnet.org (Renee Teunissen) posts:
: 
: [ Stuff deleted ]
: 
: > DKB is replaced by PoV. pov is availble at same addresses as dkb was
: > availible at nl.cs.emu.edu (128.2.222.56) in /usr/mlm/ftp
: > PoV's c source files should also be availble around here.
: 
: [ more deleted ]
: 
: > DKBtrace - another good ray tracer, from all reports; works on PCs & Mac II.
: 
: DKBTrace and POV run on just about any <= 16 bit machine.  It was originally
: written on an Amiga.  Runs on UNIX boxes, OS-9 machines, PC, Mac, VMS boxes,
: etc.  It's the most portable raytracer around.  D. Buck and the POV team
: deserve a pat on the back for their hard work keeping it portable.
:

Yes, indeed! It only took a couple of minutes to port to the Atari ST running
MiNT and using GCC 2.2.2... And let's not forget the amazing example scene
files! 

Marinos Yannikos

Newsgroups: comp.graphics
From: u926135@tasman.cc.utas.edu.au (Adrian Hassall Lewis)
Subject: image enhancement
Summary: some additions to my previous post
Keywords: image enhancement
Organization: University of Tasmania, Australia.
Date: Fri, 16 Oct 1992 04:38:20 GMT

Oops, I forgot to mention that whilst I'm using a Mac to scan, I'm also
using unix boxes also (currently sparc hopefully RS/6000 soon) so
information/software for any of these platforms is welcome.

Thanks to those people who have already responded.

Adrian

Xref: sparky comp.graphics:10467 comp.os.ms-windows.advocacy:2414 comp.os.os2.advocacy:7354 comp.sys.sgi:14928
From: hatton@socrates.ucsf.edu (Tom Hatton)
Newsgroups: comp.graphics,comp.os.ms-windows.advocacy,comp.os.os2.advocacy,comp.sys.sgi
Subject: Re: Considering getting an SGI machine...
Keywords: SGI
Date: 11 Oct 92 00:20:16 GMT
Organization: UCSF Computer Graphics Lab

hunter@phoenix.apana.org.au (James Gardiner) writes:
>dic5340@hertz.njit.edu (David Charlap) writes:
>>In article <1992Oct2.141914.8147@njitgw.njit.edu> dic5340@hertz.njit.edu (David Charlap) writes:
>>>SGI has anounced NT for one new model workstation.  It is MIPS R4000
>>>based, though, so it's likely that NT will be ported to SGI's other
>>>workstations if this one works out well.

>>One minor correction:  Apparantly (according to one of Brian's posts)
>>SGI has demoed a beta of NT on Indigoes.

>The new R4000 based pizza box type indigo system that NT will be on
>is suppose to be quite price competetive. I'd support the SGI because
>you buying a piece of REAL hardware.  It can also run IRIX(unix) if you grow
>out of NT. (you could boot up in either OS).
>Also an R4000PC (Pc version chip. no secondary cache) still wips
>a 486/50 by many times.

I believe SGI has stated that the current support of NT is a 
"technology demonstration" or something like that. Doesn't sound as
if their heart is in this. They may be throwing it at the fans to see
the response. If it isn't strong, I expect they'll bail.

Tom
Newsgroups: comp.graphics,comp.graphics.visualization,alt.binaries.pictures.d
From: rthomson@mesa.dsd.es.com (Rich Thomson)
Subject: Re: Q:problem with alt.binaries.pictures 
Reply-To: rthomson@dsd.es.com (Rich Thomson)
Organization: Design Systems Division, Evans & Sutherland, SLC, UT
Date: Mon, 12 Oct 92 20:46:06 GMT

In article <1992Oct10.200631.27381@fct.unl.pt>
	jpl@tiger.fct.unl.pt (Joao Prospero Luis [ps]) writes:
>Rich Thomson (rthomson@mesa.dsd.es.com) wrote:
>: Yes, the problem is that "alt.binaries.pictures" is no longer in
>: existence.  It was replaced by the group "alt.binaries.pictures.misc";
>
>	What do you mean "alt.binaries.pictures is no longer in existence"?
>	I am reading this in al.binaries.pictures, do you mean that this
>does not exist?

1. Discussion postings should to to a.b.p.d; sorry for the followup
   that leaked over there.

2. alt.binaries.pictures was rmgrouped long ago and replaced with
   alt.binaries.pictures.misc.

3. Your site may have aliased alt.binaries.pictures to
   alt.binaries.pictures.misc as was recommended at the time of the
   great binaries reorganization.

4. Since alt is under noone's control, groups often remain long after
   they are dead.  It is suggested that the bonafide groups be used,
   but there is no way of enforcing this.

5. Distribution of alt is spotty in places.  Using antiquated
   newsgroup names further exacerbates the problem.

							-- Rich
-- 
	Repeal the personal income tax; vote Libertarian in 1992.
Disclaimer: I speak for myself, except as noted; Copyright 1992 Rich Thomson
UUCP: ...!uunet!dsd.es.com!rthomson			Rich Thomson
Internet: rthomson@dsd.es.com	IRC: _Rich_		PEXt Programmer
Newsgroups: comp.graphics,alt.graphics
From: mcfarlin@mmedia.uucp (David McFarling)
Subject: Re: scanning slides/negatives.
Organization: Midwest Multimedia
Date: Fri, 09 Oct 1992 00:55:16 GMT
Keywords: slides,negatives,scanner,photostyler

In <1992Oct5.033655.7996@monu6.cc.monash.edu.au> steve@monu6.cc.monash.edu.au (Steve Balogh (+61 3 565 4747)) writes:

>In article <1992Oct02.212558.9303@mmedia.uucp> mcfarlin@mmedia.uucp (David McFarling) writes:
>>In <1992Sep23.212509.26254@newstand.syr.edu> cjwong@rodan.acs.syr.edu (Christopher J. Wong) writes:
>>
>>>Hi, does anyone know if it is possible to get decent images scanning
>>>slides/negatives using Aldus Photostyler and a "normal" 
>>>scanner(microtek 600Z), not a slide scanner?
>>>
>>>I've tried tweaking with the gamma curve controls, brightness/contrast
>>>, and shawdow/Highlight controls, but have been unable to achieve a 
>>>decent image.
>>>
>>
>>Probably not (depends on your definition of "normal").  I'm not
>>familiar with Microtek, but "slide" scanners capture light that has
>>passed *through* the slide, NOT bounced off it.
>
>Would this work?
>
>=====================================================  Lid of scanner
>-----------------------------------------------------  Mirror facing downwards
>-----------------------------------------------------  Your slide/negative
>=====================================================  Glass surface
>
>I guess that there may be parallax problems and/or color problems due to the
>light passing through the image twice. But is it workable?
>
>
Steve, your desperation is showing. :=)))

I'd bet against it, but it should prove an interesting exercise!  Who knows,
it might make for some special effects!  Seriously, as you guessed, light
passing through the negative twice - the second time from a different angle 
and distance should produce a color-shifted out-of-focus glob.

I don't have a thin flat mirror, or I'd try it.  E-mail me an anonymous
ftp site down there I can put them on and I'll try it and send you the files.
I may not get to until next week.

-Dave

mcfarlin@mmedia.UUCP
From: banshee@cats.ucsc.edu (Wailer at the Gates of Dawn)
Newsgroups: comp.graphics
Subject: PCXDUMP invocation from C?
Date: 9 Oct 92 02:29:30 GMT
Organization: University of California, Santa Cruz
NNTP-Posting-Host: am.ucsc.edu


	Has anyone had any success using the program PCXDUMP
(avail from simtel and mirrors) to invoke itself via an interupt from
C?  I'm having no end of problems though it works fine when invoked
directly (from the keyboard).
From: Renee.Teunissen@freudsys.nl.mugnet.org (Renee Teunissen)
Sender: Usenet@freudsys.nl.mugnet.org
Newsgroups: comp.graphics
Subject: Volume Visualization Workshop - call for posters
Date: 07 Oct 92  21:54:25 EST

To: yagel@news.cis.ohio-state.edu

Hi Roni, on 5 Oct 92  (about 3:35:27) yo wrote to All :

 RY> From: yagel@news.cis.ohio-state.edu (Roni Yagel)
 RY> Newsgroups: comp.graphics
 RY> Organization: The Ohio State University Department of Computer
 RY> and Information Science

You wrote several things about ACM/siggraph.
do you know how i become a siggraph member ?? someone told me there is a special students offer. 

can you give me an address where i can write to or even better where i can send a fax message to ???


Greetzzz,
 _
|_)
|\_enee. 

 * Origin: freusys.nl.mugnet.org, a prive uucp gate at (27:4331/107.19)
Newsgroups: comp.graphics
From: Chris_F_Chiesa@cup.portal.com
Newsgroups: comp.graphics
Subject: Re: Spyrograph Kinematics
Date: Mon, 12 Oct 92 22:40:22 PDT
Organization: The Portal System (TM)

Aside from the spelling (Kenner's product is SpIrograph, with an I, not a Y),
I have to throw my two cents in here...

I wrote a Spirograph simulator for the DEC VT240 terminal using ReGIS graph-
ics back in 1986 at Ball State University; it was extremely popular while I
was a student there, and is still on the system although probably not used
as frequently now that people are less impressed with "simple" computer gra-
phics! :-)  Anyway, I've had a lot of fun with it and have also begun port-
ing it to the Amiga...

The original was written in (cringe) VAX Basic, although I later wrote a
new version in (cringe cringe) VAX Macro assembly; the Amiga version is cur-
rently in AmigaBASIC.

I'd be interested in seeing the program whose originator started this thread
just now; what language is it and on what platform does it operate?

Anyone interested in an executable ReGIS-outputting Spirograph simulator
for VAX/VMS, or to discuss the wonders of Spirograph and its kinematics in
general, be sure to write me at the e-mail address below.  One cool thing
about SIMULATING Spirograph in a computer is that you need not be bound
by physical constraints, for instance you can make the "inner wheel" BIGGER
than the "outer ring" in which it revolves, for some physically-impossible 
effects...  And there's lots more where that comes from...

BTW I also still have my original late-60's Spirograph set, complete with
"idea book" -- the one containing all the full-color sample designs with
instructions on how to create each...  That's fun to duplicate on the screen.

Chris Chiesa
   Chris_F_Chiesa@cup.portal.com
Newsgroups: comp.graphics
From: nectar@world.std.com (Jacques A Vidrine)
Subject: Primer for image processing?
Organization: The World Public Access UNIX, Brookline, MA
Date: Tue, 13 Oct 1992 19:09:00 GMT

I have inherited some code for the processing of grayscale
images such as used in radiology.  Since I am now responsible
for its upkeep, I would like to know if anyone has pointers to
a good book I may read to bring myself somewhat up to speed
on image processing algorithms and programming.

Thanks in advance!
-- 
Jacques A. Vidrine? 	   |
nectar@world.std.com	   | "Do what thou wilt
			   |  shall be the whole of the Law"
Request my PGP public key  |
Newsgroups: comp.graphics
From: wgreen@eckhart.scd.ucar.edu (Wayne Green)
Subject: Need yacc/lex for Autocad dwg or dxf files.
Reply-To: wgreen@eckhart.scd.ucar.edu (Wayne Green)
Organization: Scientific Computing Division/NCAR, Boulder, CO
Date: Thu, 15 Oct 1992 16:33:07 GMT


We are looking at developing translators to convert data
into our own definition of a database. The interface
will be to yacc/lex files and pick the data we want
to assert to a SQL database from the grammer. I would
like mail or a FTP pointer to any yacc/lex for Autocad dwg or dxf
files. The actions of the grammer are not needed, just
the ability to "see" the files in the context of these
tools.


Thanks,,



Wayne Green      NCAR (National Center for Atmospheric Research)
FL2-1042         (303) 497-8540  FAX (303) 497-8520
P.O. Box 3000, Boulder Colorado, 80307-3000 wgreen@ncar.ucar.edu
--

Wayne Green      NCAR (National Center for Atmospheric Research)
FL2-1042         (303) 497-8540  FAX (303) 497-8520
P.O. Box 3000, Boulder Colorado, 80307-3000 wgreen@ncar.ucar.edu
From: wb104@mbuf.bio.cam.ac.uk (Wayne Boucher)
Newsgroups: comp.graphics
Subject: Re: Determining if a polygon is convex
Date: 16 Oct 92 12:11:02 GMT
Organization: U. of Cambridge, England

/*
The following is hopefully an implementation of the algorithm given by
Peter Schorn to determine whether a (planar) polygon is convex.  I have
changed the idea slightly, so beware!  The algorithm checks for those
points where the x-coordinates and y-coordinates change from increasing
to decreasing, or vice-versa.  For x (and similary for y) this must occur
exactly twice (if you think of the array as circular, not linear), and
the two x changes must alternate with the two y changes (with suitable
care taken of what is meant by alternation).  Any formal proofs that
this really works?
*/

#define  TRUE  1
#define  FALSE  0

typedef int Bool;

int ptr_x[2], ptr_y[2];

static Bool alternation()
{
    if (ptr_x[0] < ptr_y[0])
    {
	if (ptr_x[1] < ptr_y[0])  return  FALSE;
	if (ptr_x[1] > ptr_y[1])  return  FALSE;
    }
    else if (ptr_x[0] > ptr_y[0])
    {
	if (ptr_y[1] < ptr_x[0])  return  FALSE;
	if (ptr_y[1] > ptr_x[1])  return  FALSE;
    }

    return  TRUE;
}

#define  INCREASING(w, i, j)  ((w[j] > w[i]) ? TRUE : FALSE)

Bool convex_polygon(x, y, n)
    float *x, *y;
    int n;
{
    int i, j, k;
    int changes_x = 0, changes_y = 0;
    Bool dx1, dy1, dx2, dy2;

    dx1 = INCREASING(x, 0, 1);
    dy1 = INCREASING(y, 0, 1);

    for (i = 0; i < n; i++)
    {
	j = (i + 1) % n;  k = (j + 1) % n;

	dx2 = INCREASING(x, j, k);
	dy2 = INCREASING(y, j, k);

	if (dx2 ^ dx1)
	{
	    if (changes_x == 2)  return  FALSE;
	    ptr_x[changes_x++] = i;
	}

	if (dy2 ^ dy1)
	{
	    if (changes_y == 2)  return  FALSE;
	    ptr_y[changes_y++] = i;
	}

	dx1 = dx2;  dy1 = dy2;
    }

    return alternation();
}
From: gavin@krypton.asd.sgi.com (Gavin Bell)
Newsgroups: comp.graphics
Subject: Re: Help with perspective texture mapping on polygons, please help
Date: 12 Oct 1992 20:51:58 GMT
Organization: Silicon Graphics, Inc.  Mountain View, CA
NNTP-Posting-Host: krypton.asd.sgi.com

In <718762533snx@rjck.UUCP> rob@rjck.UUCP (Robert J.C. Kyanko) writes:

>I am trying to write a program which will do correct perspective texture
>mapping onto polygons.

There is a very nice article about this in the July 1992 issue of IEEE
"Computer Graphics and Applications"-- "Hyberbolic Interpolation", on
Page 89, by Jim Blinn.

You can request back issues of CG&A for $20.00 ($10.00 for IEEE members)
from:

IEEE Computer Graphics and Applications
IEEE Computer Society
PO BOX 3014
Los Alamitos CA 90720-1264

--
--gavin     (gavin@sgi.com,  (415)390-1024)
From: slzg4@cc.usu.edu
Newsgroups: comp.graphics
Subject: Need: Convert PS-file to gl-file.
Date: 13 Oct 92 14:07:00 MDT
Organization: Utah State University

Hi!
Could someone send me a program to convert a PS-file to a gl-file?
Thank you.
S. Kuntanapreeda
Newsgroups: comp.graphics,comp.graphics.visualization
From: raju@sol.cs.wmich.edu (Venkat C. Raju)
Subject: Info on (Remote) Incremental image transfer.
Organization: Computer Science Dept., Western Michigan Univ., Kalamazoo, MI.
Date: Tue, 13 Oct 1992 15:05:01 GMT

Hi,

Can someone guide me on how how to get started with Incremental Image
transfer, as to references, papers, articles etc. 

In brief, I need to interact with a remote computer with a high resolution
screen, and need to transfer the image on  to my screen regularly. So instead
of sending the whole pixel info, need to use a technique to send as less info
as possible to  get a useful picture. (I hope I am clear, I have just started
on the project and don't know much about it) Thanks in advance,

-regards,

Venkat Raju
raju@cs.wmich.edu
From: aaron@clark.edu (Aaron Auseth)
Newsgroups: comp.graphics
Subject: Weather maps?
Date: 16 Oct 92 17:46:48 GMT
Article-I.D.: clark.1992Oct16.174648.20421
Organization: Clark College, Vancouver, Wa.  USA

Where can I get the latest statalite weather maps?  I found them last year
but I can't remember where they were.

They were GIF's or something like that.  They showed the Earth with clouds
and the states borders were marked.

Anyone know where the FTP site is?
Email is fine.
From: Renee.Teunissen@freudsys.nl.mugnet.org (Renee Teunissen)
Sender: Usenet@freudsys.nl.mugnet.org
Newsgroups: comp.graphics
Subject: Re: Wang OPEN/image document imaging for AIX starts shipments
Date: 12 Oct 92  17:36:37 EST

Hi Juhana, on 9 Oct 92  (about 8:51:55) yo wrote to All :

 JK> respect
 JK> others opinions.
^^^^^^^^^^^^^^^^^^^^^^^^
 JK> Reposting the article was unnecessary.


 JK> Juhana Kouhia
 JK> =============
 JK> Vote Clinton for president!
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

and how about politics in a comp.graphics group ?
could you let politcs out of here ?

Thanx,
 _
|_)
|\_enee.

 * Origin: freusys.nl.mugnet.org, a prive uucp gate at (27:4331/107.19)
From: spl@szechuan.ucsd.edu (Steve Lamont)
Newsgroups: comp.graphics
Subject: Re: Digital Darkroom
Keywords: source book
Date: 7 Oct 92 15:40:33 GMT
Article-I.D.: network.1av0dhINNbhn
Organization: University of Calif., San Diego/Microscopy and Imaging Resource
NNTP-Posting-Host: szechuan.ucsd.edu

In article <1992Oct7.144134.8566@socrates.umd.edu> collins@socrates.umd.edu (Jim C) writes:
>I'm looking fro the source code to the book. I know I've seen it
>somewhere, I just can't remember, and it's not in my notes.

It's called popi and is available at all the usual ftp sites.
ftp.uu.net, gatekeeper.dec.com, research.att.com, and
wuarchive.wustl.edu, for instance.

							spl
-- 
Steve Lamont, SciViGuy -- (619) 534-7968 -- spl@szechuan.ucsd.edu
UCSD Microscopy and Imaging Resource/UCSD Med School/La Jolla, CA 92093-0608
"If you don't think people are this crazy, you need to move to LA!"
                                     - Gary Stollman
From: kipp@warp.asd.sgi.com (Kipp Hickman)
Newsgroups: comp.graphics.opengl
Subject: Re: Availability of OpenGL
Date: 12 Oct 1992 17:39:28 GMT
Organization: Silicon Graphics, Inc.  Mountain View, CA
NNTP-Posting-Host: warp.asd.sgi.com


In article <1bcaoiINNs4m@fido.asd.sgi.com>, kipp@warp.asd.sgi.com writes:
> 
> Another thing you can do to ease portability of IrisGL code to OpenGL
> is to always use the following style of rendering commands:
> 
> 	beginpolygon
> 		v3f
> 		v3f
> 		v3f
> 		...
> 	endpolygon
> 
> Don't use the relative move,draw stuff, or any of the move draw stuff,
> pclos, etc.  Don't use subpixel(true).

OOPS!  Make that subpixel(false)!!!  Sorry!

 					kipp hickman
 					silicon graphics inc.
From: kipp@warp.asd.sgi.com (Kipp Hickman)
Newsgroups: comp.graphics.opengl
Subject: Re: Availability of OpenGL
Date: 12 Oct 1992 16:56:50 GMT
Organization: Silicon Graphics, Inc.  Mountain View, CA
NNTP-Posting-Host: warp.asd.sgi.com


Another thing you can do to ease portability of IrisGL code to OpenGL
is to always use the following style of rendering commands:

	beginpolygon
		v3f
		v3f
		v3f
		...
	endpolygon

Don't use the relative move,draw stuff, or any of the move draw stuff,
pclos, etc.  Don't use subpixel(true).

					kipp hickman
					silicon graphics inc.
Newsgroups: comp.graphics.opengl