Path: utzoo!attcan!uunet!husc6!mailrus!cornell!uw-beaver!uoregon!markv
From: markv@uoregon.uoregon.edu (Mark VandeWettering)
Newsgroups: comp.graphics
Subject: My Raytracer, Questions Answered, and a Bug fix!
Message-ID: <2683@uoregon.uoregon.edu>
Date: 4 Sep 88 22:42:57 GMT
Reply-To: markv@drizzle.UUCP (Mark VandeWettering)
Organization: University of Oregon, Computer Science, Eugene OR
Lines: 83


First of all thanks to everyone who has expressed an interest in my
raytracer.  I wish to address some questions globally rather than to
each individual.

Q:	The raytracer seems to work, but how do I display it on my XXX
	brand workstation?

A:	Well, there are many answers to this.  We only have black and
	white sun workstations here, so I have to display my images on
	an ancient and probably quite rare Tek4115 graphics terminal
	which has only 8 bitplanes.  

	What I do is take the output of this raytracer, and pipe it
	through a program to convert it to the Utah Raster Toolkit
	format that we use here at the U of O.  We have several programs
	to display these files on a wide variety of devices.  The utah
	Raster Toolkit is available via anonymous FTP from cis.utah.edu,
	or you can send them some amount of money, and they can make you
	a tape (I don't have exact details here).

	The only problem with this is the guts of my conversion program
	are not original, they consist of some code that Eugene Miya
	posted to this group awhile ago (never write what you can beg,
	borrow or steal!), and I would have to contact him before I
	distributed said program.  Also you would have to get the Utah
	Raster stuff as well.

	If I get enough mail to warrant posting this stuff, and if I can
	verify it with Eugene Miya, I will post my programs.

	My advice:  Don't bother hacking pic.c too much.  Write a
	program to display general raster images of an rgb bitmap to
	whatever device you have on hand.  Use dithering if you want
	black and white.  And then POST such programs, so that others
	can use/improve them.

Q:	Where can I get Eric Haine's NFF package?
	
A:	Simple:  I will be reposting it right after this message.

Q:	Does anyone have any nifty NFF file objects to trace?

A:	Well, I just converted the teapot to NFF file format (using
	faceted polygons) but it is pretty big.  If someone can suggest
	an anonymous FTP site where I could put some of these, as well
	as other revisions to my programs, I would make them available
	from there.

Q:	What else am I working on?
	
	Well, I would like to add motion blur, and statistically
	optimized anti-aliasing.  I added code so that you can specify
	colors by name rather than by guessing colors.  Parametric
	patches, tori, and surfaces of revolution would be nice to add
	too. As soon as I feel the raytracer has been significantly 
	extended, I will repost.

Finally, a bug fix (courtesy of Cameron Elliot):

Your program will crash on some machines unless you do the following...
(The buf array was too small.)

Modify screen.c:

/* Was before cam...
	[Ed:  Gadzooks, Mark can sure be stupid sometimes....]
        curbuf = (Pixel *) malloc (xres * sizeof (Pixel)) + 1 ;
        buf = (Pixel *) malloc (xres * sizeof (Pixel)) + 1;
*/
        curbuf = (Pixel *) malloc ((xres+1) * sizeof (Pixel)) ;
        buf = (Pixel *) malloc ((xres+1) * sizeof (Pixel));

---
Disclaimer: If employees dont represent an organization what does?
Cameron Elliott		Portable Cellular Communications
Path: ...!uw-beaver!tikal!ptisea!cam

Thanks again for the bug fix, and the nice comments!

Keep the mail coming!  

Mark VandeWettering