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_ __ ______ _ __ ' ) ) / ' ) ) /--' __. __ , --/ __ __. _. o ____ _, / / _ , , , _ / \_(_/|_/ (_/_ (_/ / (_(_/|_(__<_/ / <_(_)_ / (_</_(_(_/_/_)_ / /| ' |/ "Light Makes Right" October 13, 1989 Volume 2, Number 7 Compiled by Eric Haines, 3D/Eye Inc, 2359 Triphammer Rd, Ithaca, NY 14850 NOTE ADDRESS CHANGE: wrath.cs.cornell.edu!eye!erich [distributed by Michael Cohen <m-cohen@cs.utah.edu>, but send contributions and subscriptions requests to Eric Haines] All contents are US copyright (c) 1989 by the individual authors Archive locations: anonymous FTP at cs.uoregon.edu (128.223.4.1) and at freedom.graphics.cornell.edu (128.84.247.85), /pub/RTNews Contents: Introduction New People and Address Changes Solid Surface Modeler Information, by Eric Haines Minimum Bounding Sphere Program, by Marshall Levine Parallelism & Modeler Info Request, by Brian Corrie ======== USENET cullings follow ======== Ray Tracer Available, by Craig Kolb Source from Roy Hall's Book, by Tim O'Connor More on Texture Mapping by Spatial Position, by Paul Lalonde Procedural Bump-mapping Query, by Prem Subrahmanyam Ray Tracer Performance on Machines, by Gavin A. Bell, Phil Dykstra, Steve Lamont Projective Mapping Explanation, by Ken "Turk" Turkowski Intersection Calculation Problem Request, Jari Toivanen Mathematical Elements for Computer Graphics - Call for Errata, by David Rogers Raytracing on NCUBE Request, by Ping Kang Hsiung Intersection Between a Line and a Polygon (UNDECIDABLE??), by Dave Baraff, Tom Duff ------------------------------------------------------------------------------- Introduction It's October, the time when the air turns chilly, the leaves turn red, and people's minds turn towards releasing a public domain version of their ray tracer. Holy smokes there's a lot of them coming out lately! This month Craig Kolb's ray tracer has become available, along with the first PD ray tracer from Australia, by David Hook. Paul Lalonde mentions that his will be coming out soon, and will include spline surfaces. Also, David Kirk and Jim Arvo have created a ray tracer which they used in their workshop in Australia, and which may be released to the general public soon. Other code that has been made available is that printed in Roy Hall's _Illumination and Color in Computer Generated Imagery_ book. Next month I hope to collect various timing information from all sorts of ray tracers on all sorts of machines. I hope to do a "trace-off" sometime soon, comparing MTV's, Craig's, DBW, QRT, ART, mine, and any others I can get up and running. If anyone else has any timings or observations on performance of ray tracers and various machines, please send them to me. ------------------------------------------------------------------------------- New People and Address Changes David Hook dgh@munnari.OZ.AU Dept. Of Engineering Computer Resources University Of Melbourne Parkville, Vic, 3052 Australia G'day. Our major area of interest in ray tracing is CSG modeling and we have a locally developed ray tracer which is a step towards this, as a department we are also involved with the Faculty of Architecture at this University, so we are starting to look at special effects somewhat more seriously than before. This has also led to a greater interest in acceleration techniques. Personally, I am currently doing a masters degree in the area of CSG and ways of introducing patches into the model. The rendering technique being used is ray tracing. [And a further note from David Hook:] The mailing list has been set up on munnari, so if you send it to rtnews@munnari.OZ.AU, it will (should) travel around Oz to the people who want it. I am asking people who subscribe if they wish to be on the contact list, etc... As a bit of additional info, I have written a ray-tracer which does CSG and renders algebraic surfaces, (ala Pat Hanrahan), although in this case it's built around Sturm Sequences and we occasionally use CSG to take cross-sections of the surfaces. The interest in algebraic surfaces began because a friend of mine was struggling with a 6th order surface known as the Hunt Surface, getting a good feel for the cusps on it was turning out to be awful using polygonal subdivision. In any case there is a public domain version of all this sitting in pub on munnari.OZ.AU (128.250.1.21) which can be got by anonymous ftp. The file is vort.tar.Z. Knowing a bit more about the whole business now, it's a bit of an embarrassment! Still it may be of interest to someone and constructive criticism is always welcome. [From a README file in his ray tracing distribution:] By the by, for people who are interested, there are an excellent series of papers on ray tracing and computer graphics in general published in the NATO ASI Series of books. The volume in question is in Vol. 40, series F, and is titled "Theoretical Foundations of Computer Graphics and CAD". It was published in 1988 Springer-Verlag. Roman Kuchkuda's paper in it "An Introduction To Ray Tracing", would be the best introductory paper we have seen to date. Apart from that it was the first paper we found that actually said what a superquadric was! -------- NAME: Hench, Stephen D. SNAIL MAIL: 2621-C Stewart Drive E MAIL: hench@csclea.ncsu.edu Raleigh, NC 27603 BRIEF: Undergrad in Mathematics and Computer Science at NCSU. Interested in ray tracing (would I want to subscribe if I wasn't?), radiosity, and rendering in general. -------- Marshall Levine 136 1937 Hall Wilson College Princeton University Princeton, NJ 08544 (609) 734-6061 Home: Marshall Levine 5212 Louise Avenue Encino, California 91316 (818) 995-6528 (818) 906-7068 E-mail: (1) mplevine@phoenix.princeton.edu or: (2) mplevine@gauguin.princeton.edu or: (3) mplevine@bogey.princeton.edu My main interests are helicopters and computer graphics. Within graphics, I am interested in animation and motion control. While I think it is great to see a ray-traced magnifying glass sitting on top of a cicuit board, I would rather see the magnifying glass fly smoothly over a spinning board while the camera flies smoothly through the scene. I am currently designing a flexible graphics language with a friend of mine, Chris Williams (Princeton U. '92). If anyone is interested, I can say more about that later. -------- Cornell Program of Computer Graphics A ray tracing mailing list has been set up by Tim O'Connor: ray-tracing-news@wisdom.graphics.cornell.edu Program of Computer Graphics 120 Rand Hall Cornell University Ithaca, NY 14853 People on this list who've already been intro'ed here include: Roy Hall, Mark Reichert, Ben Trumbore, and Tim O'Connor. New people and brief bio sketches: Wash Wawrzynek - paw@squid.graphics.cornell.edu Current interest are user interfaces and visualization for computational mechanics. -------- Len Wanger - lrw@freedom.graphics.cornell.edu My sketch is on a piece of paper, but my interests are: I am a graduate student in the department of computer graphics at Cornell University. I am interested in modeling and visual perception. -------- Filippo Tampieri - fxt@freedom.graphics.cornell.edu Areas of interest: parallel/distributed ray tracing, fast algorithms for ray tracing. -------- Ricardo Pomeranz - rxp@venus.graphics.cornell.edu Interests: constructive solid geometry and rendering -------- Paul Wanuga - phw@neptune.graphics.cornell.edu Masters student at Cornell's Computer Graphics Lab. Interests - rendering realistic complex environments in realistic times. -------- Kathy Kershaw - kershaw@hope.graphics.cornell.edu I'm Kathy Kershaw. I did the ray tracing thing once. Maybe it'll have something to do w/ my master's thesis; maybe not. -------- Colin Summers - colin@scarpa.graphics.cornell.edu Just recently interested in computer graphics and heading into the abyss from the architecture side, I have a background in personal computers and spent a year out of the design studio to computer consult in Manhattan. Glad to be back in the world of academia. As soon as someone comes across with a Macintosh like text processor for xWindows, let me know. -------- Ted Himlan - thh@squid.Graphics.Cornell.EDU Color science, radiometric measurement, array camera. interest: detailed measurements on an environment for comparison to simulation. -------- Julie O'Brien Dorsey - job@hope.graphics.cornell.edu Computer aided design applications, radiosity, lighting design -------- Francois Sillion - fxs@bruno.graphics.cornell.edu I am currently on a Post-Doc position at Cornell, after having completed my PhD at the 'Ecole Normale Superieure' in Paris, France, where my work included the development of a two-pass method for lighting calculations, combining ray tracing and radiosity. My interests are illumination models (local and global), animation and interactivity. ------------------------------------------------------------------------------- Solid Surface Modeler Information, by Eric Haines The Solid Surface Modeler from NASA finally came out. The disappointing news is that even though it's "a non-profit unit of the University of Georgia," the thing is priced at $1250 for a cartridge tape and documentation (which is $43 separately). The reason I mention it is this newsletter is that it was used for some rather elaborate databases that were both modeled and ray traced on the AT&T Pixel Machine. Unfortunately, it's unclear whether the Pixel Machine driver program is included in the distribution. The modeler itself sounds reasonable, source code comes on the tape, and there seems to be no restrictions on the use of the software. It's a pity that it's pricey when compared to, say, FSF stuff, but I guess someone has to pay for those glossy advertisement folders. >From their literature: "SSM was written in standard C with Silicon Graphic's Iris Graphics Library calls and AT&T PicLib calls.... The program is available for the Silicon Graphics IRIS workstation running version 3.1 of IRIX, and a Sun Workstation with AT&T PXM964 running 4.2 BSD." For more information contact: COSMIC The University of Georgia 382 East Broad Street Athens, GA 30602 (404)-542-3265 ------------------------------------------------------------------------------- Minimum Bounding Sphere Program, by Marshall Levine I think you will be interested in the following program. It is a minimum-bounding-sphere program. As the explained in the header comments, the main algorithm seems to solve the problem in linear time. Please let me know what you think. { clusters.p Written by Marshall Levine (Princeton University '92) e-mail: mplevine@phoenix.princeton.edu Algorithm designed by Marshall Levine and Chris Williams (Princeton U. '92) This program searches through a 3-dimensional space of randomly distributed points for a cluster of 10 stars within the smallest radius possible. I first implemented a "pri" list. This is a linked list of real numbers (representing distances). The list is kept in order. However, when a number that would go farther into the list than the number of points per sphere (NUMINSPHERE) tries to go into the list, the insert procedure stops it. This is done because the distance is useless. For example, if NUMINSPHERE is 5 and a number would be inserted into the 7th slot in the list, it is not inserted. The minimum radius of a sphere with 5 points would be determined by the 5th element of the list (not including the header), so any number inserted after the 5th element is useless and is therefore not inserted. If there are not NUMINSPHERE elements in the pri, then there are not enough points to fill the sphere. The brute-force algorithm loops through every point in space. For each point, the algorithm finds the distance between that point and every other point and puts that distance into the pri. When all points have been compared against this point, the NUMINSPHERE'th element is taken to be the minimum radius of a sphere centered at this point containing NUMINSPHERE points. However, points are not compared against themselves, so the exact number of comparisons is N^2-N, making this an N^2 algorithm. The efficient algorithm designed by Chris Williams and me divides the space into a 3-dimensional grid. If the grid is divided into NUMPOINTS/NUMINSPHERE sectors, then at least one of the sectors must have at least NUMINSPHERE points. Now, make spheres with the same volume as the sectors. At least one sphere surrounding one point will have at least NUMINSPHERE points. It turns out that the tradeoff between fewer computations and more overhead is minimized by choosing the grid to have enough sectors such that each sector is r/2 on each side (where r is the radius of the aforementioned sphere). Our algorithm starts with a sphere radius equal to the distance from one corner of the unit cube to another (3^.5). Given the first point in the list, we compare that point against every other point in sectors touching the sphere (In this case, every other point in space!) By storing the distances and then taking the NUMINSPHERE'th number from the pri list, as in the brute algorithm, we frequently reduce the size of the sphere. Then, we check the next point with the new, smaller sphere size and continue in this way until we have tested every point. As we go along, the minimum sphere size keeps shrinking until for any given point, we only check a few neighboring sectors, if any. In practice, this radius shrinks so quickly that the algorithm displays LINEAR BEHAVIOR! NOTE: This program was written for clarity, not for efficiency. If it is to be used in any real applications, there are many ways to speed it up. Bruteforce: Our algorithm: (Average of 3 runs) Points: #Comparisons: comps/points: #Comparisons: comps/points: 50 2450 49.000 958 19.160 75 5550 74.000 1241 16.547 100 9900 99.000 2111 21.110 150 22350 149.000 2785 18.567 200 3689 18.445 250 5120 20.480 300 6010 20.033 350 7149 20.426 400 7658 19.145 600 11404 19.007 800 16781 20.976 1000 20438 20.438 Testing 50 points. Brute-force: Best sphere: 0.3067962678 Number of comparisons: 2450 Efficient Algorithm: Best sphere: 0.3067962678 Number of comparisons: 946 %time cumsecs #call ms/call name 31.6 0.10 1 100.01 _brutecluster <==== 10.5 0.18 1 33.34 _elegantcluster <==== 5.3 0.25 101 0.17 _clearprilist 5.3 0.27 581 0.03 _insertprilist 5.3 0.28 1 16.67 _makespace Testing 300 points. Brute-force: Best sphere: 0.1569231423 Number of comparisons: 89700 Efficient Algorithm: Best sphere: 0.1569231423 Number of comparisons: 5617 %time cumsecs #call ms/call name 44.2 3.27 1 3267.00 _brutecluster <==== 2.9 6.82 1 216.69 _elegantcluster <==== 1.1 7.00 2358 0.04 _insertprilist 0.2 7.33 601 0.03 _clearprilist 0.0 7.38 1 0.00 _makespace } {==========================================================================} program clusters(input,output); const MAXNUMPOINTS = 501; { The maximum # of points we can handle } NUMINSPHERE = 10; { # stars to find inside sphere } INFINITY = 999999.9; { Larger than largest distance possible } MAXUSESPACE = 20; { Maximum length per edge of space-grid } PI = 3.1415926535; type datatype = real; point = record { The type of a point } x : real; y : real; z : real; data : datatype; end; ptr = ^node; node = record { Linked list for a distances list called "pri" } data : real; next : ptr; end; sptr = ^spacenode; { Linked list for each sector in the space-grid } spacenode = record index : integer; { Stores index of that point in points[] } next : sptr; end; var rndnm : integer; { Needed for the random number generator } points : array [1..MAXNUMPOINTS] of point; { All points in space } listhead : ptr; { List head for distances list called "pri" } space : array[0..MAXUSESPACE, 0..MAXUSESPACE, 0..MAXUSESPACE] of sptr; { The space-grid (hereafter called 'grid') } spacesize, usespace : integer; { Size per edge of grid } NUMPOINTS : integer; { The number of points we have in space } { **************** Support routines for random generators ************** } procedure seed; { Seed the random number generator } begin writeln('seed:'); readln(rndnm); end; function rndom(scale : integer) : real; { Make random real from 0 to scale } begin rndnm := abs(abs((rndnm*921+1)) mod 32749); rndom := (rndnm*scale/32749) end; procedure randompoint(var pt : point); { Generate a random point within } begin { a unit cube. } pt.x := rndom(1); pt.y := rndom(1); pt.z := rndom(1) end; procedure generatepoints; { Generate NUMPOINTS points in space } var x : integer; begin for x := 1 to NUMPOINTS do randompoint(points[x]) end; { *************** Support routines for the "pri" list ******************** } procedure initprilist; { Initialize the pri list } begin new(listhead); listhead^.data := 0.0; new(listhead^.next); listhead^.next^.data := INFINITY; listhead^.next^.next := nil end; procedure clearprilist; { Clear the pri list } var p,oldp : ptr; begin p := listhead; while p <> nil do begin oldp := p; p := p^.next; dispose(oldp) end; new(listhead); listhead^.data := 0.0; new(listhead^.next); listhead^.next^.data := INFINITY; listhead^.next^.next := nil end; procedure insertprilist(r : real); { Insert a distance into pri list } var p,oldp,temp : ptr; { "pri" is just a linked list of distances } x : integer; { kept in low -> high order. The catch is } begin { that if a number should be inserted after } x := 1; { the NUMINSPHERE'th node, we don't bother } p := listhead^.next; { inserting it, because it isn't in the } oldp := listhead; { smallest sphere with NUMINSPHERE points. } while (r > p^.data) and (x <= NUMINSPHERE) do begin oldp := p; p := p^.next; x := x + 1 end; if x <= NUMINSPHERE then begin new(temp); temp^.data := r; temp^.next := p; oldp^.next := temp end end; function getbiggestinsphere : real; { Returns value of the NUMINSPHERE'th } var x : integer; { element in pri list, or INFINITY } p : ptr; { if the list isn't that long. } begin x := 1; p := listhead^.next; while (x < NUMINSPHERE) and (p <> nil) do begin x := x + 1; p := p^.next end; if (x < NUMINSPHERE) or (p = nil) then getbiggestinsphere := INFINITY else getbiggestinsphere := p^.data end; procedure printprilist; { Print the pri list, for debugging } var p : ptr; begin p := listhead; { DO print the head } while p <> nil do begin writeln(p^.data:15:10); p := p^.next end; writeln('nil') end; { ******************* Miscellaneous support routines ******************** } procedure printpoint(pt : point); { Print out a point } begin writeln('(',pt.x:8:5,',',pt.y:8:5,',',pt.z:8:5,')') end; function cube(x : real) : real; { Return cube root of a number } begin cube := exp((1/3)*ln(x)) end; { *********************** Brute Force algorithm ************************* } procedure brutecluster; { Find minimum sphere containing NUMINSPHERE } { points by testing the distance between } { every point. } var distx,disty,distz,dist : real; { Find distance between two points } bestsphere,trysphere : real; { Find minimum sphere } numcomps : integer; { # comparisons } thispoint,againstpoint : integer; { Counters } begin clearprilist; { Kill the priority list } bestsphere := INFINITY; numcomps := 0; for thispoint := 1 to NUMPOINTS do { Test every point... } begin clearprilist; for againstpoint := 1 to NUMPOINTS do { ...against every other point } if thispoint <> againstpoint then { Don't compare point against self} begin distx := points[thispoint].x - points[againstpoint].x; disty := points[thispoint].y - points[againstpoint].y; distz := points[thispoint].z - points[againstpoint].z; dist := sqrt(distx*distx + disty*disty + distz*distz); numcomps := numcomps + 1; if dist < bestsphere then { If dist less than smallest sphere,} insertprilist(dist) { insert distance into pri list } end; trysphere := getbiggestinsphere; { Get 'NUMINSPHERE'th item from list } if trysphere < bestsphere then { If this radius is the smallest yet,} bestsphere := trysphere; { then remember it. } end; writeln('Brute-force:'); writeln(' Best sphere: ',bestsphere:15:10); writeln(' Number of comparisons: ',numcomps:8) end; { **************************** My algorithm *********************** } procedure makespace; { Build the space-grid. See documentation at } var x,y,z : integer; { beginning of program for details. } temp : sptr; thispoint : integer; begin spacesize := trunc(cube(8*PI*NUMPOINTS/NUMINSPHERE)); usespace := spacesize-1; if usespace > MAXUSESPACE then writeln('****** NOT ENOUGH MEMORY FOR GRID'); for x := 0 to usespace do for y := 0 to usespace do for z := 0 to usespace do space[x,y,z] := nil; { Clear the grid } for thispoint := 1 to NUMPOINTS do { Go through every point... } begin new(temp); temp^.index := thispoint; x := trunc(points[thispoint].x * spacesize); y := trunc(points[thispoint].y * spacesize); z := trunc(points[thispoint].z * spacesize); temp^.next := space[x,y,z]; { Put this point into proper } space[x,y,z] := temp; { sector in grid. } end end; procedure elegantcluster; { Find smallest sphere containing NUMINSPHERE } { points by looping through every point, } { checking ROUGHLY only the points within } { a radius less than or equal to the } { minimum radius found so far. } var bestsphere,trysphere : real; xmin,xmax,ymin,ymax,zmin,zmax : integer; { Dimensions of box to check } thispoint : integer; { The current point to test against } x,y,z : integer; { The current grid we are testing } distx,disty,distz,dist : real; { For computing distances } numcomps : integer; { # comparisons } cpindex : sptr; { Pointer into point list for a grid sector } begin makespace; bestsphere := 1.732050808; { Start with radius of distance from one } numcomps := 0; { corner of unit cube to other: 3^.5 } for thispoint := 1 to NUMPOINTS do { Loop for every point } begin clearprilist; xmin := trunc((points[thispoint].x - bestsphere) * spacesize); xmax := trunc((points[thispoint].x + bestsphere) * spacesize); ymin := trunc((points[thispoint].y - bestsphere) * spacesize); ymax := trunc((points[thispoint].y + bestsphere) * spacesize); zmin := trunc((points[thispoint].z - bestsphere) * spacesize); zmax := trunc((points[thispoint].z + bestsphere) * spacesize); if xmin < 0 then xmin := 0; if ymin < 0 then ymin := 0; { Get dimensions of box } if zmin < 0 then zmin := 0; { containing every sector in } if xmax > usespace then xmax := usespace; { grid that we want to check } if ymax > usespace then ymax := usespace; { against the current point } if zmax > usespace then zmax := usespace; for x := xmin to xmax do for y := ymin to ymax do for z := ymin to ymax do { Loop through every sector in this box } begin cpindex := space[x,y,z]; while cpindex <> nil do { Test against every point in this sector} begin if thispoint <> cpindex^.index then { Don't test point against } begin { itself. } distx := points[thispoint].x - points[cpindex^.index].x; disty := points[thispoint].y - points[cpindex^.index].y; distz := points[thispoint].z - points[cpindex^.index].z; dist := sqrt(distx*distx + disty*disty + distz*distz); numcomps := numcomps + 1; if dist < bestsphere then { If dist less than smallest sphere} insertprilist(dist) { insert distance into pri list } end; cpindex := cpindex^.next { Get next point in this sector } end end; trysphere := getbiggestinsphere; if trysphere < bestsphere then bestsphere := trysphere end; writeln('Efficient Algorithm:'); writeln(' Best sphere: ',bestsphere:15:10); writeln(' Number of comparisons: ',numcomps:8) end; begin seed; writeln('How many points?'); readln(NUMPOINTS); if NUMPOINTS < NUMINSPHERE then writeln('***** Must have at least ',NUMINSPHERE:1,' points.') else begin writeln('Testing ',NUMPOINTS:1,' points.'); initprilist; generatepoints; brutecluster; elegantcluster end end. ------------------------------------------------------------------------------- Parallelism & Modeler Info Request, by Brian Corrie ...!uw-beaver!uvicctr!bcorrie bcorrie@uvicctr.UVic.ca [soon to be a posting on USENET, but it hadn't reached my node yet.] Howdy folks.... It's survey time again, and I would appreciate your participation in this version of twenty questions. I am interested in parallel algorithms for ray tracing, and I am curious about a couple of things. Please note that I have most of the "standard references" that get cited in the literature, but I am interested in some of the OTHER stuff that is out there. The papers that I have: Cleary et al. "Multiprocessor Ray Tracing", Internal Report, 83/128/17, Department of Computer Science, University of Calgary, Calgary, Alberta, Canada. Dippe et al "An Adaptive Subdivision Algorithm and Parallel Architecture for Realistic Image Synthesis", Computer Graphics, Volume 18, Number 3. Gaudet et al "Multiprocessor Experiments for High Speed Ray Tracing", ACM TOG, Volume 7, Number 3. etc..... What I am interested in are references to some of the goodies that are out there in the real world. Are there any papers on the hardware Pixar uses. How about the AT&T pixel machine, the Connection Machine (there is a piece on it in Scientific American, Volume 256, Number 6 that I already have), and other bizarre architectures. Dave Jevans from the University of Calgary (Hi Dave, remember me? I met you at SIGGRAPH this year) mentioned at one point he implemented some stuff on a BBN Butterfly (I think). Any more info on that Dave? Did you write it up? Anybody else doing anything similar? Here is the info I want.... 1) What architecture do you run on? 2) Parallel, vectorized etc? For parallel systems: 3) How many processors do you use? 4) How tightly coupled are they? 5) Do you perform any load balancing, and if so how? 6) Architectural requirements (memory/node, communications etc)? 7) Anything else you can think of that might be useful. Thanks in advance for any help you can give me. Replies by email are of course the best route to take, but I read comp.graphics every morning, so a reply here will be seen. I will post a summary to the net if I get enough information. ======== Question number two.... This should be quick and easy. I would like to know what kind of modelling software people use out there in the real world. We have all seen the pretty pictures, but how do they get created? I would appreciate a quick or not so quick review of what kind of software is used at your site to model 3D scenes. For those of you in the RT News mailing list and don't read the net like I do, I will send a copy of both this and the summary to Eric. Thanks, Brian ======== USENET cullings follow =============================================== Ray Tracer Available, by Craig Kolb From: craig@weedeater.math.yale.edu Newsgroups: comp.graphics Organization: Math Department, Yale University All of this talk of solid texturing and the like has convinced me to pull together my raytracer for public consumption. Although I'm calling this a beta release, relatives of this version of rayshade have been making pretty pictures for about a year now. For examples, see slides 32 and 57 from the SIGGRAPH '89 technical slide set and slides 67/68 from the stereo slide set. If there's enough interest, I'll post rayshade to comp.sources.unix once the bugfixes stop rolling in. [I would like to add that Craig's ray tracer is fairly nice, and most of the portability problems and minor bugs have been fixed since its release. Its input language is much more full featured than NFF (which, I'll say again, was made only for testing ray tracers, not photorealism) and looks more mainstream than some of the other public domain ray tracers I've seen. If you're looking for a reasonable input language, check his out. His latest and greatest version (i.e. newer that 2.21) might be available via ftp by now. - EAH] -- Rayshade, a raytracing program, is available for "Beta" testing. Rayshade reads a multi-line ASCII file describing a scene to be rendered and produces a Utah Raster RLE format file of the raytraced image. Features: Primitives: boxes cones cylinders height fields planes polygons spheres triangles (flat- or Phong-shaded) [he forgot to mention there are also superquadrics! - EAH] Composite objects Point, directional, and extended (area) light sources Solid texturing and bump mapping of primitives, objects, and individual instances of objects Antialiasing through adaptive supersampling or "jittered" sampling Arbitrary linear transformations of primitives, instances of objects, and texture/bump maps Use of uniform spatial subdivision and/or hierarchy of bounding volumes to speed rendering Options to facilitate rendering of stereo pairs Support for the Linda parallel programming language An awk script is provided to translate NFF format scripts to rayshade format. Rayshade is written in C with parsing support provided through lex and yacc. The C, lex and yacc files comprise approximately eight thousand lines of code. Sites without lex and yacc can make use of the C source files produced by lex and yacc which are included in this distribution. Rayshade has been tested on a number of UNIX-based machines, including Vaxes, Sun Workstations, Iris 4D Workstations, Encore Multimax, AT&T 3B2/310, Cray XMP, and IBM RTs. In addition, support is provided for the Amiga using the Aztec C compiler. Rayshade makes use of the Utah Raster toolkit, a package consisting of a large number of useful image manipulation programs, test images, and a library to read and write images written using the toolkit's RLE format. The toolkit is available via anonymous FTP from cs.utah.edu or from weedeater.math.yale.edu. Those sites that cannot or do not want to use the Utah Raster toolkit can make use of a compile-time option to produce images written using a generic file format identical to that used in Mark VandeWettering's "MTV" raytracer. This version of rayshade is a "beta" release. The first "real" release will include an updated manual page and additional documentation as well as any bugfixes or extensions born out of this release. Rayshade is copyrighted in a "Gnu-like" manner. Rayshade is available via anonymous ftp from weedeater.math.yale.edu (192.26.88.42) in pub/Rayshade.2.21.tar.Z. The Utah Raster toolkit is available in pub/UtahToolkit.tar.Z. ------------------------------------------------------------------------------- Source from Roy Hall's Book, by Tim O'Connor From: toc@batcomputer.tn.cornell.edu Newsgroups: comp.graphics Straight from the dragon's mouth (so to speak) comes the source from "Illumination and Color in Computer Generated Imagery" by Roy Hall. It's now available via anonymous ftp from: freedom.graphics.cornell.edu (128.84.247.85) It's under pub/Hall and comes in two files: 1) README (of course) which also contains some code necessary to convert 2) code.tar.Z.a which contains the actual code. So, as always, read README first. Those of you who do not have ftp access may wish to drop me a short line (a Subject: of "gimme roy's source" is adequate). If there's enough interest I'll post to this group, if not I'll (shudder!) attempt to mail it right to you. Also of interest on freedom are the Ray Tracing News archives (under pub/RTNews) and the Xcu Widget Set. (Sorry, this code available only in stores, no mailing.) fishing in McElligot's Pool, to'c ------------------------------------------------------------------------------- I decided to repost the above two notes again, since they are very worthwhile. For the rest of the USENET cullings, check the archives.