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Path: abcfd20.larc.nasa.gov!amiga-request From: amiga-request@abcfd20.larc.nasa.gov (Amiga Sources/Binaries Moderator) Subject: v90i258: DKBTrace 2.01 - DKBtrace Ray-Tracer, Part10/10 Reply-To: David Schanen <mtv@milton.u.washington.edu> Newsgroups: comp.sources.amiga Message-ID: <comp.sources.amiga:v90i258@abcfd20.larc.nasa.gov> References: <comp.sources.amiga:v90i249@abcfd20.larc.nasa.gov> Date: 03 Sep 90 23:22:50 GMT Approved: tadguy@uunet.UU.NET (Tad Guy) X-Mail-Submissions-To: amiga@uunet.uu.net X-Post-Discussions-To: comp.sys.amiga Submitted-by: David Schanen <mtv@milton.u.washington.edu> Posting-number: Volume 90, Issue 258 Archive-name: applications/dkbtrace-2.01/part10 #!/bin/sh # This is a shell archive. Remove anything before this line, then unpack # it by saving it into a file and typing "sh file". To overwrite existing # files, type "sh file -c". You can also feed this as standard input via # unshar, or by typing "sh <file", e.g.. If this archive is complete, you # will see the following message at the end: # "End of archive 10 (of 10)." # Contents: Docs/dkb.doc # Wrapped by tadguy@abcfd20 on Mon Sep 3 19:21:23 1990 PATH=/bin:/usr/bin:/usr/ucb ; export PATH if test -f 'Docs/dkb.doc' -a "${1}" != "-c" ; then echo shar: Will not clobber existing file \"'Docs/dkb.doc'\" else echo shar: Extracting \"'Docs/dkb.doc'\" $65462 characters$ sed "s/^X//" >'Docs/dkb.doc' <<'END_OF_FILE' X X X X X X X DKBtrace Ray-Tracer, Amiga/IBM Version 2.0 X X "It's free, and it's well worth the price!" X X X X X X X X This program was written by: X X David Buck X 22C Sonnet Cres. X Nepean, Ontario X Canada, K2H 8W7 X X It has been made freely distributable. The author retains the copyright X to the program but authorizes free distribution by BBS'es, networks or X by magnetic media. The distributer may choose to charge for the cost of X the disk but should not sell the software for profit. Non-profit X organizations such as clubs may charge for the software so long as the X price is reasonable (less than $5.00 more than the cost of the disk) and X so long as the buyers are informed that the program is freely X distributable. X X The images and data files generated by the raytracer are the property of X the user of the software and may be used for any purpose without X restriction. X X The author makes no guarantees or warantees with this program and claims X no responsibility for any damage or loss of time caused by this program. X Bug reports may be sent to the author but the author is under no X obligation to provide bug fixes, features, or any support for this X software. X X I would also like to place the following conditions on the use of this X program: X X 1) that it should not be used as part of any commercial package without X my explicit written consent. X X 2) if you make any neat and interesting pictures, please send them to X me. X X 3) If you make any changes to the source code, please let me know. I'd X like to see what you've done. X X 4) This text file should accompany the program. X X X X I can be reached on the following BBS'es X X ATX (613) 526-4141 X OMX (613) 731-3419 X Mystic (613) 731-0088 or (613) 731-6698 X FidoNet 1:163/109.9 X Bitnet David_Buck@Carleton.CA X X X X XSection 0.1 - Recent Update History: X X Version 1.2 First release X Version 2.0 Conversion to the IBM done by Aaron A. Collins X New textures, Specular and Phong highlighting added by X Aaron A. Collins X Triangle, Smooth Triangle, Sphere, Plane support added by X David Buck X RAW, IFF and GIF image mapping added by David Buck and Aaron X Collins X Transparency and Fog added by David Buck X GIF format file reader by Steve Bennett (used with permission) X New Noise and DNoise functions by Robert Skinner X (used with permission) X X Aaron Collins can be reached on the following BBS'es X X Lattice BBS (708) 916-1200 X The Information Exchange BBS (708) 945-5575 X Stillwaters BBS (708) 403-2826 X X AAC: As of July of 1990, there will be a Ray-Trace specific BBS in the X (708) Area Code (Chicago suburbia) for all you Traceaholics out there. X The phone number of this new BBS is (708) 358-5611. I will be Co-Sysop X of that board. There is also a new Ray-Trace and Computer-Generated X Art specific SIG on Compuserve, GO COMART. And now, back to the DOCS... X X Version 2.0 includes ANSI-C function prototyping for ALL functions, X TARGA format output file capability, and a reversal of the order of X writing screen data from the original DKB/QRT "RAW" file format. For X IBM's, it has a crude VGA 320x200 by 256 color display rendering X ability. If the image requested is larger than 320x200, every other X pixel horizontally and vertically is dropped from the display to keep it X all on the screen. X X Version 2.0 compiles under Turbo-C 2.0 on the IBM P.C. and Lattice C X 5.05 on the Amiga. The only file which contains the ANSI extensions is X dkbproto.h, so for non-ANSI compilers, you only need to remove the X declaration of the parameters in the config.h file and the whole thing X should compile. There are several example config.h files for Amiga, X IBM, and Unix. The appropriate one should be copied over CONFIG.H, and X the MAKEFILE should be edited for your particular system and compiler X configuration before compilation. X X Version 2.0 has a significant difference from prior releases: Speed! X The new primitives of SPHERE, PLANE, TRIANGLE, etc. greatly speed up X tracing. Another significant speed-up is that world X-Y-Z values beyond X 10 Million or so are ignored, and ray tracing beyond that distance will X cease. This produces 2 minor peculiarities: X X 1) A black stripe at the horizon point of Pre-2.0 scene description X .data files that have "ground" and "sky" planes defined. The X planes were traced out to a much greater "infinity" so this effect X was unnoticeable, prior to version 2.0. X 2) Tiny black pixels in the texture, or "Surface Acne". X X X This is usually caused by rays being refracted or reflected such that X the ray does not happen to hit any object, and eventually becomes black X in color as it gets too far away and gets clipped. This effect can be X minimized by enclosing the scene with distant "walls", "floors", or X placing "ocean floors" beneath water, etc. So far, no scenes have X required placing such planes behind the camera, unless an "environment X map" of sorts is desired. See SKYTEST.DAT for several examples of X spurious distant planes. If your "acne" still doesn't go away, it may X be due to a large pixel sample area and it's accidentally picking a point X which is just inside the primitive being hit. This is a more tricky X problem to solve, and anti-aliasing the image will definitely help if X this sort of thing occurs. X X For IBM's, the program PICLAB by the Stone Soup Group offers excellent X image post-processing features and has direct TARGA 16/24/32 file format X compatibility, and will serve to palette map and translate the TARGA X images into .GIF's, etc. The commercial application AUTODESK ANIMATOR X offers a CONVERT utility that also does an excellent job of palette X mapping a TARGA to .GIF format. COLORIX VGA PAINT also offers TARGA X format reading and conversion facilities. Those of you with real TARGA X boards can view the files directly in 16 million colors and are lucky X and should know it! X X The Stone Soup Group also produces FRACTINT, the best fractal/Mandelbrot X program available at ANY price (and it too is FREE!) for the PC. I X (AAC) have borrowed their Public Domain .GIF file reading routines for X the Image Map texture. Here is their Copyright Notice from the GIF X Decoder module: X X * DECODER.C - An LZW decoder for GIF X * Copyright (C) 1987, by Steven A. Bennett X * X * Permission is given by the author to freely redistribute and include X * this code in any program as long as this credit is given where due. X * X * In accordance with the above, I want to credit Steve Wilhite, who X * wrote the code which this is heavily inspired by... X * X * GIF and 'Graphics Interchange Format' are trademarks (tm) of X * Compuserve, Incorporated, an H&R Block Company. X X X XSection 0.5 - Program Description: X X X This program is a ray tracer written completely in C. It supports X arbitrary quadric surfaces (spheres, ellipsoids, cones, cylinders, X planes, etc.), constructive solid geometry, and various shading models X (reflection, refraction, marble, wood, and many others). It also has X special-case code to handle spheres, planes, triangles, and smooth X triangles. By using these special primitives, the rendering can be done X much more quickly than by using the more general quadrics. X In order to create pictures with this program, you must describe the X objects in the world. This description is a text file called X "<filename>.data", and <filename> defaults to "object" if not specified. X Normally, such files are difficult to write and to read. In order to X make this task easier, the program contains a two-pass parser to read X the data file. It allows the user to easily create complex worlds from X simple components. Since the parser allows include files, the user may X put the object descriptions into different files and combine them all X into one final image. X X This manual is divided into four main sections. The first section X describes the command-line parameters for the program. The second X section describes the syntax and semantics of the description language. X Some sample worlds and their corresponding images are provided on the X disk. The third section details how to display and convert the images X using various postprocesors, and section four has a collection of handy X hints for using the tracer most effectively as well as some quick start X procedures. X X XSection 1 - Command Line Parameters X X This program is designed to be run from the CLI, although it can be run X from the Workbench if desired. From the CLI, the program accepts X various parameters: X X -wxxx width of the picture in pixels X (On the Amiga, use 319 for full-sized pictures) X -hxxx height of the picture in pixels X (On the Amiga, use 400 for full-sized pictures) X X +v verbose option - print out the scan line number. X -v disable verbose option X X +f produce an output file X -f don't produce an output file X X If the +f option is used, the ray tracer will produce an X output file of the picture. This output file describes each X pixel with 24 bits (8 bits for red, 8 for green, and 8 for X blue). A post processor (Amiga only) called "DumpToIFF" can X convert this format to hi-res HAM format (320 x 400) making X reasonable choices for the colour registers. For compati- X bility, the format of the dump file is the same as the format X for the QRT ray tracer. With Version 2.0, you can substitute X the "t" character for the "f" character and produce output X files directly in the Truevision (R) TARGA 24 format. This X format is remarkably like the QRT/DKB raw format, so it was X easily done, and allows for a wider range of post-processing X programs to be used. The extension .TGA is normally used for X such files, but any may be chosen. X X +d display the picture while tracing X -d don't display the picture while tracing X X If the +d option is used, then the picture will be displayed X while the program performs the ray tracing. On the Amiga, X this picture is not as good as the one created by "DumpToIFF" X because it does not try to make optimum choices for the colour X registers. Version 2.0 will produce a display on an IBM-PS/2 X compatible VGA/MCGA display in 320x200 x 256 colours if the +d X option is given (Anyone for adding in SVGA resolutions??) but X the same basic caveat is still applicable: A good post- X processor will make better choices of the most popular colors X in the image to map to the display. X X +p wait for prompt (beep and pause) before quitting X -p finish without waiting X X The +p option makes the program wait for a carriage return X before exiting (and closing the graphics screen). This gives X you time to admire the final picture before destroying it. X X X -ifilename set the input filename X -ofilename set output filename X X If your input file is not "Object.data", then you can use -i X to set the filename. The default output filename will be X "data.display" on Amiga's, and either "data.dis" or "data.tga" X on IBM's, depending on the output file format that is being X used. If you want a different output file name, use the -o X option. X X +a[xxx] anti-alias - xxx is an optional tolerance level (default 0.3) X -a don't anti-alias X X The +a option enables adaptive anti-aliasing. The number X after the +a option determines the threshold for the anti- X aliasing. If the colour of a pixel differs from its neighbor X (to the left or above) by more than the threshold, then the X pixel is subdivided and super-sampled. The samples are X jittered to introduce noise and make the pictures look better. X If the anti-aliasing threshold is 0.0, then every pixel is X supersampled. If the threshold is 1.0, then no anti-aliasing X is done. Good values seem to be around 0.2 to 0.4. X X +x allow early exit by hitting any key (IBM only) X -x lock in trace until finished (IBM only) X X On the IBM, the -e option disables the ability to abort the X trace by hitting a key. If you are unusually clumsy or have X CATS that stomp on your keyboard (like I do - AAC :-)), you X may want to use it. If you are writing a file, the system X will recognize ^C at the end of line if BREAK is on (on the X IBM). If you aren't writing a file, you won't be able to X abort the trace until it's done. X X This option was meant for big, long late-nite traces that take X ALL night (or longer!), and you don't want them interrupted by X anything less important than a natural disaster such as hur- X ricane, fire, flood, famine, etc. X X -bxxx use an output file buffer of xxx kilobytes. X (if 0, flush the file on every line - this is the default) X X The -b option allows you to assign large buffers to the output X file. This reduces the amount of time spent writing to the X disk and prevents unnecessary wear (especially for floppies). X If this parameter is zero, then as each scanline is finished, X the line is written to the file and the file is flushed. On X most systems, this operation insures that the file is written X to the disk so that in the event of a system crash or other X catastrophic event, at least part of the picture has been X stored properly on disk. X X X -sxxx start tracing at line number xxx. X -exxx end tracing at line number xxx. X X The -s option is provided for when some natural or unnatural X catastrophe has occurred, and you want to restart the trace at X a given line number after the crash. One is subtracted from X the given line number if anti-aliasing is activated (the prior X line's being computed is required for the anti-aliasing mech- X anism to function properly). It can also be used to re-render X parts of an image (perhaps with anti-aliasing turned on). A X separate utility can then merge the new lines into the old X file. The particularly faint of heart or weak of power supply X may want to batch the image in "strips" of 10-20 lines and X concatenate them later. X X -qx rendering quality X X The -q option allows you to specify the image rendering X quality. The parameter can range from 0 to 9. The values X correspond to the following quality levels: X X 0,1 Just show colours. Ambient lighting only. X 2,3 Show Diffuse and Ambient light X 4,5 Render shadows X 6,7 Create surface textures X 8,9 Compute reflected, refracted, and transmitted rays. X X The default is -q9 (maximum quality) if not specified. X X You may specify the default parameters by modifying the file X "trace.def" which contains the parameters in the above format. X This filename contains a complete command line as though you X had typed it in, and is processed before any options supplied X on the command line are recognized. X X X X XSection 2 - The Object Description Language X X The Object Description Language allows the user to describe the world in X a readable and convenient way. X X The language delimits comments by the left and right braces ({ and }). X Nested comments are allowed, but no sane person uses them anyway, right? X X The language allows include files to be specified by placing the line: X X INCLUDE "filename" X X at any point in the input file (Include files may be nested). X X XSection 2.1 - The Basic Data Types X X There are several basic types of data: X X Float X Floats are represented by an optional sign (+ or -), some digits, an X optional decimal point, and more digits. It does not support the "e" X notation for exponents. The following are valid floats: X X 1.0 -2.0 -4 +34 X X Vector X Vectors are arrays of three floats. They are bracketed by angle X brackets ( < and > ), and the three terms usually represent x, y, and z. X For example: X X < 1.0 3.2 -5.4578 > X X Colour X A colour consists of a red component, a green component, a blue X component, and possibly an alpha component. All four components are X floats in the range 0.0 to 1.0. The syntax for Colours is the word X "COLOUR" followed by any or all of the RED, GREEN, BLUE or ALPHA X components in any order. X X For example: X X COLOUR RED 1.0 GREEN 1.0 BLUE 1.0 X COLOUR BLUE 0.56 X COLOUR GREEN 0.45 RED 0.3 ALPHA 0.3 X X Alpha is a transparency indicator. If an object's colour contains some X transparency, then you can see through it. If Alpha is 0.0, the object X is totally opaque. If it is 1.0, it is totally transparent. X X For those people who spell "Colour" the American way as "Color", the X program also accepts "COLOR" as equivalent to "COLOUR" in all instances. X X COLOUR_MAP X For wood, marble, spotted, agate, granite, and gradient texturing, the X user may specify arbitrary colours to use for the texture. This is done X by a colour map or "colour spline". When the object is being textured, X a number between 0.0 and 1.0 is generated which is then used to form the X colour of the point. A Colour map specifies the mapping used to change X these numbers into colours. The syntax is as follows: X X COLOUR_MAP X [start_value end_value colour1 colour2] X [start_value end_value colour1 colour2] X ... X END_COLOUR_MAP X X The value is located in the colour map and the final colour is X calculated by a linear interpolation between the two colours in the X located range. X XSection 2.2 - The More Complex Data Types X X The data types used to describe the objects in the world are a bit more X difficult to describe. To make this task easier, the program allows X users to describe these types in two ways. The first way is to define X it from first principles specifying all of the required parameters. The X second way allows the user to define an object as a modification of X another object (the other object is usually defined from first X principles but is much simpler). Here's how it works: X X You can use the term DECLARE to declare a type of object with a certain X description. The object is not included in the world but it can be used X as a "prototype" for defining other objects, as this basic example X shows: X X DECLARE Sphere = QUADRIC X <1.0 1.0 1.0> X <0.0 0.0 0.0> X <0.0 0.0 0.0> X -1.0 X END_QUADRIC X X To then reference the declaration elsewhere in your source file or in X another included one, and to actually include the object in the world, X you would define the object using object definition syntax, like this: X X OBJECT X QUADRIC Sphere X SCALE <20.0 20.0 20.0> X END_QUADRIC X COLOUR White X AMBIENT 0.2 X DIFFUSE 0.8 X END_OBJECT X The real power of declaration becomes apparent when you declare several X primitive types of objects and then define an object with several X component shapes, using either COMPOSITE methods or the CSG methods X INTERSECTION, UNION, or DIFFERENCE. More on those later. Also, using X the DECLARE keyword can make several objects share a texture without the X need for each object to store a duplicate copy of the same texture, for X more efficient memory usage. Example: X X OBJECT { A Hot dog in a Hamburger Bun (?) } X UNION X QUADRIC Sphere X SCALE <20.0, 10.0, 20.0> X END_QUADRIC X QUADRIC Cylinder_X X SCALE <40.0, 20.0, 20.0> X END_QUADRIC X END_UNION X END_OBJECT X X X Viewpoint X The viewpoint tells the ray tracer the location and orientation of the X camera. The viewpoint is described by four vectors - Location, X Direction, Up, and Right. Location determines where the camera is X located. Direction determines the direction that the camera is X pointed. Up determines the "up" direction of the camera. Right X determines the direction to the right of the camera. X X A first principle's declaration of a viewpoint would look like this: X X VIEWPOINT X LOCATION < 0.0 0.0 0.0> X DIRECTION < 0.0 0.0 1.0> X UP < 0.0 1.0 0.0 > X RIGHT < 1.0 0.0 0.0> X END_VIEWPOINT X X This format becomes cumbersome, however, because the vectors must be X calculated by hand. This is especially difficult when the vectors are X not lined up with the X, Y, and Z axes as they are in the above example. X To make it easier to define the viewpoint, you can define one viewpoint, X then modify the description. For example, X X VIEWPOINT X LOCATION < 0.0 0.0 0.0> X DIRECTION < 0.0 0.0 1.0> X UP < 0.0 1.0 0.0 > X RIGHT < 1.0 0.0 0.0 > X TRANSLATE < 5.0 3.0 4.0 > X ROTATE < 30.0 60.0 30.0 > X END_VIEWPOINT X X In this example, the viewpoint is created, then translated to another X point in space and rotated by 30 degrees about the X axis, 60 degrees X about the Y axis, and 30 degrees about the Z axis. X X Unfortunately, even this is somewhat cumbersome. So, in version 2.0, X you can now specify two more parameters: X X SKY <vector> X LOOK_AT <vector> X X The SKY keyword tells the viewpoint where the sky is. It tries to keep X the camera's UP direction aligned as closely as possible to the sky. X The LOOK_AT keyword tells the camera to look at a specific point. The X camera is rotated as required to point directly at that point. By X changing the SKY vector, you can twist the camera while still looking X at the same point. X X Note that a pinhole camera model is used, so no focus or depth-of-field X effects are supported at this time. X X X Version 2.0 of the raytracer includes the ability to render fog. To add X fog to a scene, place the following declaration outside of any object X definitions: X X FOG X COLOUR ... the fog colour X 200.0 ... the fog distance X END_FOG X X Shapes X Shapes describe the shape of an object without mentioning any surface X characteristics like colour, lighting and reflectivity. The most X general shape used by this system is called a Quadric Surface. Quadric X Surfaces can produce shapes like spheres, cones, and cylinders. The X easiest way to define these shapes is to include the standard file X "BasicShapes.data" into your program and to transform these shapes X (using TRANSLATE, ROTATE, and SCALE) into the ones you want. To be X complete, however, I will describe the mathematical principles behind X quadric surfaces. Those who are not interested in the mathematical X details can skip to the next section. X X A quadric surface is a surface in three dimensions which satisfies the X following equation: X X X A y**2 + B y**2 + C z**2 X + D xy + E xz + F yz X + G x + H y + I z + J = 0 X X X (Did you really want to know that? I didn't think so. :-) DKB) X X Different values of A,B,C,...J will give different shapes. So, if you X take any three dimensional point and use its x, y, and z coordinates in X the above equation, the answer will be 0 if the point is on the surface X of the object. The answer will be negative if the point is inside the X object and positive if the point is outside the object. Here are some X examples: X X X**2 + Y**2 + Z**2 - 1 = 0 Sphere X X**2 + Y**2 - 1 = 0 Cylinder along the Z axis X X**2 + Y**2 + Z = 0 Cone along the Z axis X X General quadric surfaces can be defined as follows: X X QUADRIC X < A B C > X < D E F > X < G H I > X J X END_QUADRIC X X XSection 2.3 - Quadric surfaces the easy way X X Now that doesn't sound so hard, does it? Well, actually, it does. Only X the hard-core graphics fanatic would define his objects using the X QUADRIC definition directly. Even I don't do it that way and I know how X it works (Well, at least I worked it out once or twice :-) - DKB). X X Fortunately, there is an easier way. The file "BasicShapes.data" already X includes the definitions of many quadric surfaces. They are centered X about the origin (0,0,0) and have a radius of 1. To use them, you can X define shapes as follows: X X X INCLUDE "BasicShapes.data" X X QUADRIC X Cylinder_X X SCALE < 50.0 50.0 50.0 > X ROTATE < 30.0 10.0 45.0 > X TRANSLATE < 2.0 5.0 6.0 > X END_QUADRIC X X X You may have as many transformation lines (scale, rotate, and translate) X as you like in any order. Usually, however, it's easiest to do a scale X first, one or more rotations, then finally a translation. Otherwise, X the results may not be what you expect. (The transformations always X transform the object about the origin. If you have a sphere at the X origin and you translate it then rotate it, the rotation will spin the X sphere around the origin like planets about the sun). X X X XSection 2.4 - Spheres X X Since spheres are so common in ray traced graphics, A SPHERE primitive X has been added to the system. This primitive will render much more X quickly than the corresponding quadric shape. The syntax is: X X SPHERE <center> radius END_SPHERE X X You can also add translations, rotations, and scaling to the sphere. X For example, the following two objects are identical: X X OBJECT X SPHERE < 0.0 25.0 0.0 > 10.0 END_SPHERE X COLOR Blue X AMBIENT 0.3 X DIFFUSE 0.7 X END_OBJECT X X OBJECT X SPHERE < 0.0 0.0 0.0 > 1.0 X TRANSLATE <0.0 25.0 0.0> X SCALE <10.0 10.0 10.0> X END_SPHERE X COLOR Blue X AMBIENT 0.3 X DIFFUSE 0.7 X END_OBJECT X X Note that Spheres may only be scaled uniformly. You cannot use: X X SCALE <10.0 5.0 2.0> X X on a sphere. If you need oblate spheroids such as this, use a scaled X quadric "Sphere" shape instead. X XSection 2.5 - Planes X X Another primitive provided to speed up the raytracing is the PLANE. X This is a flat infinite plane. To declare a PLANE, you specify the X direction of the surface normal to the plane (the UP direction) and the X distance from the origin of the plane to the world's origin. As with X spheres, you can translate, rotate, and scale planes. Examples: X X PLANE <0.0 1.0 0.0> -10.0 END_PLANE { A plane in the X-Z axes 10 X units below the world origin. } X X PLANE <0.0 1.0 0.0> 10.0 END_PLANE { A plane in the X-Z axes 10 X units above the world origin. } X X PLANE <0.0 0.0 1.0> -10.0 END_PLANE { A plane in the X-Y axes 10 X units behind the world origin.} X X XSection 2.6 - Triangles X X In order to make more complex objects than the class of quadrics will X permit, a new primitive shape for triangles has been added. There are X two different types of triangles: flat shaded triangles and smooth X shaded (Phong) triangles. X X Flat shaded triangles are defined by listing the three vertices of the X triangle. For example: X X TRIANGLE < 0.0 20.0 0.0> X < 20.0 0.0 0.0> X <-20.0 0.0 0.0> X END_TRIANGLE X X The smooth shaded triangles use Phong Normal Interpolation to calculate X the surface normal for the triangle. This makes the triangle appear to X be a smooth curved surface. In order to define a smooth triangle, X however, you must supply not only the vertices, but also the surface X normals at those vertices. For example: X X SMOOTH_TRIANGLE X { points surface normals } X < 0.0 30.0 0.0 > <0.0 0.7071 -0.7071> X < 40.0 -20.0 0.0 > <0.0 -0.8664 -0.5 > X <-50.0 -30.0 0.0 > <0.0 -0.5 -0.8664> X END_SMOOTH_TRIANGLE X X As with the other shapes, triangles can be translated, rotated, and X scaled. X X NOTE: Triangles cannot be used in CSG INTERSECTION or DIFFERENCE types X (described next) since triangles have no clear "inside". The CSG UNION X type works acceptably but with no difference from a COMPOSITE object. X X XSection 2.7 - Constructive Solid Geometry (CSG) X X This ray tracer supports Constructive Solid Geometry in order to make X the object definition abilities more powerful. Constructive Solid X Geometry allows you to define shapes which are the union, intersection, X or difference of other shapes. Unions superimpose the two shapes. This X has the same effect as defining two separate objects, but is simpler to X create and/or manipulate. Intersections define the space where the two X surfaces meet. Differences allow you to cut one object out of another. X X X X X X X X X CSG Intersections, Unions, and Differences can consist of two or more X shapes. They are defined as follows: X X OBJECT X INTERSECTION X QUADRIC X ... X END_QUADRIC X X QUADRIC X ... X END_QUADRIC X X QUADRIC X ... X END_QUADRIC X END_INTERSECTION X ... X END_OBJECT X X UNION or DIFFERENCE may be used instead of INTERSECTION. The order of X the shapes doesn't matter except for the DIFFERENCE shapes. For CSG X differences, the first shape is visible and the remaining shapes are cut X out of the first (in reverse order from version 1.2 DIFFERENCE's). X X Constructive solid geometry shapes may be translated, rotated, or scaled X in the same way as a Quadric surface. The quadric surfaces making up X the CSG object may be individually translated, rotated, and scaled as X well. X X When using CSG, it is often useful to invert an shape so that it's X inside-out. The INVERSE keyword can be used to do this for any SPHERE, X PLANE, or QUADRIC. When INVERSE is used, the "inside" of the object is X flipped to be the "outside". For Planes, "inside" is defined to be "in X the opposite direction to the "normal" or "up" direction. X X Note that performing an INTERSECTION between an shape and some other X INVERSE shapes is the same as performing a DIFFERENCE. In fact, the X DIFFERENCE is actually implemented in this way. X XSection 2.8 - Objects X X There is more to defining an object than just its shape. You must tell X the ray tracer about the properties of the surface like colour, alpha, X reflectivity, refractivity, the index of refraction, and so on. To do X this, you must define Objects. X X X X X X X X A typical object definition looks something like this: X X OBJECT X QUADRIC Sphere X TRANSLATE < 40.0 40.0 60.0 > X END_QUADRIC X X TEXTURE X 0.05 X END_TEXTURE X X AMBIENT 0.3 X DIFFUSE 0.7 X REFLECTION 0.3 X REFRACTION 0.3 X IOR 1.05 X COLOUR RED 1.0 GREEN 1.0 BLUE 1.0 ALPHA 0.5 X END_OBJECT X X The following keywords may be used when defining objects: X X AMBIENT value X - Ambient light is light that is scattered everywhere in the room. X An object lit only by ambient light will appear to have the same X brightness over the entire surface. The default value is very X little ambient light (0.3). The value can range from 0.0 to 1.0. X X DIFFUSE value X - Diffuse light is light coming from a light source that is scattered X in all directions. An object lit only by diffuse light looks like X a rubber ball with a spot light shining on it. The value can range X from 0.0 to 1.0. By default, there is mostly diffuse lighting X (0.7). X X BRILLIANCE value X - Objects can be made to appear more metallic by increasing their X brilliance. This controls the tightness of the basic diffuse X illumination on objects and minorly adjusts the appearance of X surface shininess. The default value is 1.0. Higher values from X 3.0 to about 10.0 can give objects a somewhat more shiny or X metallic appearance. This is best used in concert with either X SPECULAR or PHONG highlighting. X X REFLECTION value X - By setting the reflection value to be non-zero, you can give the X object a mirrored finish. It will reflect all other objects in the X room. The value can range from 0.0 to 1.0. By default there is no X reflection. X X X X X X REFRACTION value X - By setting the refraction value to be non-zero, the object is made X transparent. Light will be refracted through the object like a X lens. The value can be set between 0.0 and 1.0. There is no X refraction by default. X IOR value X - If the object is refracting light, then the IOR or Index of X Refraction should be set. This determines how dense the object is. X A value of 1.0 will give no refraction. The Index of Refraction X for Air is 1.0, Water is 1.33, glass is 1.5, and diamond is 2.4. X X PHONG value X - Controls the amount of Phong Specular Reflection highlighting on X the object. Causes bright shiny spots on the object, the colour of X the light source that is being reflected. The size of the spot is X defined by the value given for PHONGSIZE below. PHONG's value is X typically from 0.0 to 1.0, where 1.0 causes complete saturation of X the object's colour to the light source's colour at the brightest X area (center) of the highlight. There is no PHONG highlighting X given by default. X X PHONGSIZE value X - Controls the size of the PHONG Highlight on the object, sort of an X arbitrary "glossiness" factor. Values range from 1.0 (Very Dull) X to 100 (Highly Polished). Default PHONGSIZE is 40 (plastic?) if X not specified. This is simulating the fact that slightly reflect- X ive objects, especially metallic ones, have microscopic facets, X some of which are facing in the mirror direction. The more that X are facing that way, the shinier the object appears, and the X tighter the specular highlights become. Phong measures the average X of facets facing in the mirror direction from the light sources to X the viewer. X X SPECULAR value X - Very similar to PHONG Specular Highlighting, but a better model is X used for determining light ray/object intersection, so a more X credible spreading of the highlights occur near the object X horizons, supposedly. PHONG is thus included for mostly academic X reasons, but try them both and you decide which you like better. X This effect is most obvious for light sources behind objects. The X size of the spot is defined by the value given for ROUGHNESS below. X Like PHONG, SPECULAR values are typically from 0.0 to 1.0 for full X saturation. Default is no SPECULAR highlighting. X X ROUGHNESS value X - Controls the size of the SPECULAR Highlight on the object, relative X to the object's "roughness". Values range from 1.0 (Very Rough) to X 0.001 (Very Smooth). The default value if not specified is 0.05 X (Plastic?). The roughness or average directional distribution of X the microfacets is facing in the same direction as the perpen- X dicular surface "normal" cause the most notable reflection of the X highlight to the observer. X X COLOUR value X - The colour of an object can be set by using this option. The value X is a colour or a colour constant. For example: X X COLOUR RED 1.0 BLUE 0.4 X X - or - X X DECLARE Yellow = COLOUR RED 1.0 GREEN 1.0 X ... X COLOUR Yellow X X X TRANSLATE vector X ROTATE vector X SCALE vector X - Objects can be translated, rotated, and scaled just like surfaces. X This feature is included for consistency. X X LIGHT_SOURCE X - If the LIGHT_SOURCE keyword is used in the definition of an object, X then the object is included in the list of light sources. It can X light objects and produce shadows. (You should also specify the X COLOUR of the light source). Light sources have a peculiar re- X striction: The light source MUST be TRANSLATED to it's final X position in the scene, so the normal way to define a light source X is a sphere or quadric centered about the origin, then TRANSLATED X to where desired in the final scene. For example: X X OBJECT X SPHERE <0.0 0.0 0.0> 2.0 END_SPHERE {could be a quadric, too.} X TRANSLATE <100.0 120.0 40.0> X X LIGHT_SOURCE X COLOUR RED 1.0 GREEN 1.0 BLUE 1.0 X AMBIENT 1.0 X DIFFUSE 0.0 X END_OBJECT X X X TEXTURE X - The texture feature is an experiment into functionally based X modelling. This feature allows you to assign more interesting X colouring schemes to objects. Many procedural surface textures are X provided, and by using different colour maps with them, nearly X infinite permutations are possible. For example, you can make some X object look like wood or marble, etc. X X X X X X X The basic TEXTURE syntax is as follows: X X TEXTURE X 0.05 X WOOD X TURBULENCE 0.2 X TRANSLATE < 1.0 2.0 3.0 > X ROTATE < 0.0 10.0 40.0 > X SCALE < 10.0 10.0 10.0 > X END_TEXTURE X X The transformations are optional. They allow you to transform the X texture independent of the object itself. If you are doing animation, X then the transformations should be the same as the object X transformations so that the texture follows the object. X X The floating-point value given immediately following the texture keyword X is an optional "texture randomness" value, which causes a minor random X scattering of calculated colour values and produces a sort of "dithered" X appearance. X X Instead of using WOOD, you may use MARBLE, BOZO, CHECKER, or a handful X of other interesting textures. The WOOD and MARBLE textures are X perturbed by a turbulence function. This makes them look more random X and irregular than they would normally appear. The amount of turbulence X can be changed by the TURBULENCE keyword followed by a number. Values X from 0.1 to 0.3 seem to give the best results. The default is 0.0, or X no turbulence. X X Note some of the textures given are coloration textures, such as MARBLE, X WOOD CHECKER, GRANITE, and AGATE. These work with colour maps, and have X default "colour maps" they resort to if none are given. The rest of the X textures available are "surface perturbation" textures, and do not dir- X ectly affect the colour of the object, but rather the surface's apparent X orientation in space. Examples of this are WAVES, RIPPLES, DENTS, BUMPS, X and WRINKLES. Note that any given texture may include up to two actual X textures, one coloration and one surface perturbation choice per X texture. This would allow rippled wood, or dented granite combinations, X etc., but keep in mind that any transformations applied to one texture X (i.e. TRANSLATE or SCALE) will also transform the other one in the same X fashion. X X X The following textures are available: X X CHECKER texturing gives a checker-board appearance. This option works X best on planes. When using the CHECKER texturing, you must specify two X colours immediately following the word CHECKER. These colours are the X colours of alternate squares in the checker pattern. The default X orientation of the CHECKER texture is on an X-Z plane (good for ground X work, etc.) but to use it on an object which has mostly X-Y orientation X (such as a sphere, for instance), you must ROTATE the texture. X X To rotate the CHECKER texture onto an X-Y plane: X X TEXTURE X CHECKER COLOUR White COLOUR Red X SCALE <10.0 10.0 10.0> X ROTATE <-90.0 0.0 0.0> { Checkers now in the X-Y plane... } X END_TEXTURE X X As mentioned above, for coloration textures such as WOOD, MARBLE, and X BOZO, etc., you may change the colouring scheme by using a colour map. X This map allows you to convert numbers from 0.0 to 1.0 (which are X generated by the ray tracer) into ranges of colours. For example, the X default BOZO colouring can be specified by: X X TEXTURE X BOZO X COLOUR_MAP X [0.0 0.4 COLOUR White COLOUR White] X [0.4 0.6 COLOUR Green COLOUR Green] X [0.6 0.8 COLOUR Blue COLOUR Blue] X [0.8 1.0 COLOUR Red COLOUR Red] X END_COLOUR_MAP X END_TEXTURE X X BOZO texture basically takes a noise function and maps it onto the X surface of an object. This "noise" is defined for every point in space. X If two points are close together, they will have noise values that are X close together. If they are far apart, their noise values will be X fairly random relative to each other. X X The easiest way to see how it works is to try it. With a good choice of X colours it produces some of the most realistic looking cloudscapes you X have ever seen. Try a cloud color map such as: X X TEXTURE X BOZO X TURBULENCE 1.0 { A blustery day. For a calmer one, try 0.2 } X COLOUR_MAP X [0.0 0.5 COLOUR RED 0.5 GREEN 0.5 BLUE 1.0 {blue to blue} X COLOUR RED 0.5 GREEN 0.5 BLUE 1.0] X [0.5 0.6 COLOUR RED 0.5 GREEN 0.5 BLUE 1.0 {blue to white} X COLOUR RED 1.0 GREEN 1.0 BLUE 1.0] X [0.6 1.001 COLOUR RED 1.0 GREEN 1.0 BLUE 1.0 {white to grey} X COLOUR RED 0.5 GREEN 0.5 BLUE 0.5] X END_COLOUR_MAP X SCALE <800.0 800.0 800.0> X TRANSLATE <200.0 400.0 100.0> X END_TEXTURE X X (Check out sunset.dat for a really neat (but slow) sky pattern) X X X X The color map above indicates that for small values of texture, use a X sky blue color solidly until about halfway turbulent, then fade through X to white on a fairly narrow range. As the white clouds get more turb- X ulent and solid towards the center, pull the color map toward grey to X give them the appearance of holding water vapor (like typical clouds). X SPOTTED - Spotted texture is a sort of swirled random spotting of the X colour of the object. If you've ever seen a metal organ pipe you know X about what it looks like (a galvanized garbage can is close...) Play X with this one, it might render a decent cloudscape during a very stormy X day (?). No extra keywords are required. Should work with colour maps. X With small scaling values, looks like masonry or concrete. X X AGATE - this texture is similar to Marble, but uses a different turb- X ulence function. The TURBULENCE keyword has no effect, and as such it X is always very turbulent. X X GRADIENT - this is a specialized texture that uses approximate local X coordinates of an object to control colour map gradients. This texture X ONLY works with colour maps (one MUST be given!) and has a special <X, X Y, Z> triple given after the GRADIENT keyword, which specifies any (or X all) axes to perform the gradient action on. (Example: a Y gradient X <0.0, 1.0, 0.0> will give an "altitude colour map", along the Y axis). X Values other than 0.0 are taken as 1.0 and others are meaningless. For X smooth repeating gradients, you should use a nearly "circular" colour X map, that is, one in which the first colour value (0.0) is the same as X the last one (1.001) so it "wraps around" and will cause smooth X repeating gradient patterns. Scaling the texture is normally required X to achieve the number of repeating shade cycles you want. X Transformation of the texture is useful to prevent a "mirroring" effect X from either side of the central 0 axes. Here is an example of a X gradient texture which uses a sharp "circular" color mapped gradient X rather than a smooth one, and uses both X and Y gradients to get a X diagonally-oriented gradient. It produces a dandy candy cane texture! X X TEXTURE X GRADIENT < 1.0 1.0 0.0 > X COLOUR_MAP X [0.00 0.25 COLOUR RED 1.0 GREEN 0.0 BLUE 0.0 X COLOUR RED 1.0 GREEN 0.0 BLUE 0.0] X [0.25 0.75 COLOUR RED 1.0 GREEN 1.0 BLUE 1.0 X COLOUR RED 1.0 GREEN 1.0 BLUE 1.0] X [0.75 1.001 COLOUR RED 1.0 GREEN 0.0 BLUE 0.0 X COLOUR RED 1.0 GREEN 0.0 BLUE 0.0] X END_COLOUR_MAP X SCALE <30.0 30.0 30.0> X TRANSLATE <30.0 -30.0 0.0> X END_TEXTURE X X X You may also specify a TURBULENCE value with the gradient to give a X more irregular colour gradient. This may help to do neat things like X fire or coronas. X X GRANITE - A colouring texture. This uses a simple 1/f fractal noise X function to give a pretty darn good grey granite texture. Typically X used with small scaling values (2.0 to 5.0). Also looks good with a X little dithering (texture randomness). Should work with colour maps, so X try your hand at pink granite or alabaster! X X RIPPLES - As mentioned above, you may optionally specify a surface X perturbation texture which can be used in conjunction with the above X coloration textures. RIPPLES is one example of a surface perturbation X texture. This texture makes the surface look like ripples of water. X The RIPPLES option requires a value to determine how deep the ripples X are: X X TEXTURE X WOOD X RIPPLES 0.3 X TRANSLATE < 1.0 2.0 3.0 > X ROTATE < 0.0 10.0 40.0 > X SCALE < 10.0 10.0 10.0 > X END_TEXTURE X X (In this case, the WOOD, MARBLE, or BOZO, etc. keywords are optional). X If a different colouring is specified (WOOD, MARBLE, or BOZO), then the X COLOUR parameter is ignored (except for light sources where it gives the X light colour or when rendering with a low -q option). X X WAVES - Another option that you may want to experiment with is called X WAVES. This works in a similar way to RIPPLES except that it makes waves X with different frequencies. The effect is to make waves that look more X like deep ocean waves. (I haven't done much testing on WAVES, so I can't X guarantee that it works very well). X X Both WAVES and RIPPLES respond to a texturing option called PHASE. The X PHASE option allows you to create animations in which the water seems to X move. This is done by making the PHASE increment slowly between frames. X The range from 0.0 to 1.0 gives one complete cycle of a wave. X X BUMPS - Approximately the same turbulence function as SPOTTED, but uses X the derived value to perturb the surface normal. This gives the X impression of a "bumpy" surface, random and irregular, sort of like an X orange. After the BUMPS keyword, supply a single floating point value X for the amount of surface perturbation. Values typically range from 0.0 X (No Bumps) to 1.0 (Extremely Bumpy). Values beyond 1.0 may do wierd X things. X X DENTS - Also a surface normal perturbing texture. Interesting when used X with metallic textures, it gives impressions into the metal surface that X look like dents. A single value is supplied after the DENTS keyword to X indicate the amount of denting required. Values range from 0.0 (No X Dents) to 1.0 (Fairly Dented). Use larger values at your own risk... X Scale the texture to make the pitting more or less frequent. X X X WRINKLES - This is sort of a 3-D (normal perturbing) GRANITE. It uses X a similar 1/f fractal noise function to perturb the surface normal in 3D X space. With ALPHA values of greater than 0.0, could look like wrinkled X cellophane. Requires a single value after the WRINKLES keyword to X indicate the amount of wrinkling desired. Values from 0.0 (No Wrinkles) X to 1.0 (Very Wrinkled) are typical. X X X IMAGEMAP - This is a very special coloration texture that allows you to X import a bitmapped file in RAW format (the format output by the ray- X tracer), IFF format or Compuserve GIF format and map that bitmap onto an X object. In the texture of an object, you must give the IMAGEMAP key- X word, the format, and a file name. The syntax is: X X IMAGEMAP [gradient] RAW "filename [ONCE]" X or IMAGEMAP [gradient] IFF "filename [ONCE]" X or IMAGEMAP [gradient] GIF "filename [ONCE]" X X The texture will then be mapped onto the object as a repeating pattern. X The ONCE keyword places only one image onto the object instead of an X infinitely repeating tiled pattern. When ONCE is used, the object's X default colour is used as the colour outside of the image. X X X By default, the image is mapped onto the XY plane in the range (0.0, X 0.0) to (1.0, 1.0). If you would like to change this default, you may X use an optional gradient <x, y, z> vector after the word IMAGEMAP. This X vector indicates which axes are to be used as the u and v (local surface X X-Y) axes. The vector should contain one positive number and one X negative number to indicate the u and v axes, respectively. You may X translate, rotate, and scale the texture to map it onto the object's X surface as desired. Here is an example: X X INCLUDE "BasicShapes.data" X X OBJECT X QUADRIC Plane_XY END_QUADRIC X TRANSLATE <0.0 -20.0 0.0> X X TEXTURE X { make this texture use the x and z axes for the mapping. } X IMAGEMAP <1.0 0.0 -1.0> GIF "image.gif" X SCALE <40.0 40.0 40.0> X END_TEXTURE X END_OBJECT X X When I was bored with nothing to do, I decided that it would be neat to X have turbulent texture maps. So, I said - "what the hell!" You can X specify TURBULENCE with texture maps and it will perturb the image. It X may give some bizarre results. Is this useful? I dunno. It was easy X to do so I did it. Try it out and see what you get. X XSection 2.9 - Composite Objects X X Often it's useful to combine several objects together to act as a whole. X A car, for example, consists of wheels, doors, a roof, etc. A composite X object allows you to combine all of these pieces into one object. This X has two advantages. It makes it easier to move the object as a whole X and it allows you to speed up the ray tracing by defining bounding X shapes that contain the objects. (Rays are first tested to see if they X intersect the bounding shape. If not, the entire composite object is X ignored). Composite objects are defined as follows: X X COMPOSITE X OBJECT X ... X END_OBJECT X X OBJECT X ... X END_OBJECT X ... X X SCALE < 2.0 2.0 2.0 > X ROTATE < 30.0 45.0 160.0 > X TRANSLATE < 100.0 20.0 40.0 > X END_COMPOSITE X X Composite objects can contain other composite objects as well as regular X objects. Composite objects cannot be light sources (although any number X of their components can). This is because it is nearly impossible to X determine the true "center" of the composite object, and our light X sources are pinpoint ray sources from the center of the light source X object, wherever that may be. X X XSection 2.95 - Bounding Shapes X X Let's face it. This program is no speed demon. You can save yourself X a lot of time, however, if you use bounding shapes around any complex X objects. Bounding shapes tell the ray tracer that the object is totally X enclosed by a simple shape. When tracing rays, the ray is first tested X against the simple bounding shape. If it strikes the bounding shape, X then the ray is further tested against the more complicated object X inside. X X To use bounding shapes, you simply include the following lines into the X declaration of your OBJECT or COMPOSITE_OBJECT: X X BOUNDED_BY X a shape X END_BOUND X X X X An example of a Bounding Shape: X X OBJECT X INTERSECTION X SPHERE <0.0 0.0 0.0> 2.0 END_SPHERE X PLANE <0.0 1.0 0.0> 0.0 END_PLANE X PLANE <1.0 0.0 0.0> 0.0 END_PLANE X END_INTERSECTION X X BOUNDED_BY X SPHERE <0.0 0.0 0.0> 2.0 END_SPHERE X END_BOUND X END_OBJECT X X The best bounding shape is a SPHERE since this shape is highly X optimized. Any shape may be used, however. X XSection 3 - Showing the final pictures X X When the ray tracer draws the picture on the screen, it does not make X good choices for the colour registers. Without knowing all the needed X colours ahead of time, only approximate guesses can be made. A post- X processor is really needed to view the final image correctly. A post- X processor has been provided for the Amiga which scans the picture and X chooses the best possible colour registers. It then redisplays the X picture. For the Amiga, "DumpToIFF" can optionally save this picture in X IFF format. The syntax for the DumpToIFF post-processor is: X X DumpToIFF filename X X where the filename is the one given in the -o parameter of the ray X tracer. If you didn't specify the -o option, then use: X X DumpToIFF data.dis X X If you want to save to an IFF file, then put the name of the IFF file X after the name of the data file: X X DumpToIFF data.dis picture X X This will create a file called "picture" which contains the IFF image. X X For the IBM, you will probably want to use the -t option and write the X image out in TARGA 24 format. If you have a TARGA or compatible display X adapter, you may view the picture in the full 16 million colors (that's X why they still cost the big $$ bucks). If you don't, there are several X post-processing programs available to convert the TARGA true-color image X into a more suitable color-mapped image (such as .GIF). If you have a X VGA or MCGA adapter capable of 320x200 by 256 colors, then you may use X the -d option which will display the image as it generates using only X approximate screen colors. No hardware test is performed, so if you X don't have a VGA or MCGA, -> DON'T <- use the -d option! X X When displaying the image to screen, a HSV conversion method is used X (hue, saturation, value). This is a convenient way of translating X colors from a "true color" format (16 million) down a "colour mapped" X format of something reasonable (like 256), while still approximating the X color as closely as the available display hardware permits. As X mentioned previously, the tracer has no way of knowing which colors will X be finally used in the image, nor can it deal properly with all of the X colors which will be generated (up to 16M), so only 4 shades each of 64 X possible hues are mapped into the palette DAC, as well as black, white, X and two grey levels. The advantage a post-processor has in choosing X mapped colors is that it can throw away all the unused colors in the X palette map, and thereby free up some space for making better gradient X shades of the colors that are actually used. X X There are several available image processing programs that can do this, X a public domain one that is very good is PICLAB, by the Stone Soup Group X (the folks who brought you FRACTINT). The procedure is to load the X TARGA file, then use the MAKEPAL command to generate a 256 color map X which is the histogram-weighted average of the most-used colors in the X image (You could also PLOAD a palette file from FRACTINT or one you X previously had saved using PSAVE). You then MAP the palette onto the X image one of two ways: X X 1) If the DITHER variable is OFF, a nearest-match-color-fit is used, X which can sometimes produce unwanted "banding" of colored regions X (called false contours). X 2) If the DITHER variable is ON, then a standard dither is used to X determine final color values. This is much better at blending the X color bands, but can produce noise in reflections and make mirrors X appear dirty or imperfect. X X Then you would typically SHOW the image or GSAVE it into GIF format. X While the picture is still in the unmapped form (TARGA, etc.) you can X perform a variety of advanced image processing transformations and X conversions, so save the .TGA or .RAW files you make (in case you ever X get a TARGA card, or give them to a friend who has one!). X X A commercial product that also does a good job of nearest-match-color- X fit is the CONVERT utility of The AutoDesk Animator. However, the X dither effect is not as good as that of PICLAB. To convert the file in X AA's CONVERT, you LOAD TARGA, then in the CONVERT menu, go to the SCALE X function and just hit RENDER. Click on the DITHER (lights up with an X asterisk when on) if you want it to use it's dithering. CONVERT will X scale (if asked to) and then do a histogram of total used colors like X PICLAB, but then makes 7 passes on the color map and image to determine X shading thresholds of each hue. This nearly eliminates the color X banding (false contours) without resorting to dithering. By now you X must get the feeling DITHER is a 4-letter word. If you have a low- X resolution display, it is. If you have too few colors, however, it can X be a saving grace. At resolutions of 640x400 or higher the "spray X paint" effect of dithering and anti-aliasing is much less noticeable, X and effects a much smoother blending appearance. X XSection 4 - Handy Hints/Quick Start X X - To see a quick version of your picture, use -w64 -h80 as command X line parameters on the Amiga. For the IBM, try -w80 -h50. This X displays the picture in a small rectangle so that you can see how X it will look. X X - Try using the sample default files for different usages - QUICK.DEF X shows a fast postage-stamp rendering (80x50, as above) to the X screen only, LOCKED.DEF will display the picture with anti-aliasing X on (takes forever) with no abort (do this before you go to bed...). X The normal default options file TRACE.DEF is read and you can X supersede this with another .DEF file by specifying it on the X command line, for example: X X trace -iworld.dat -oworld.out quick.def X X - When translating light sources, translate the OBJECT, not the X QUADRIC surface. The light source uses the center of the object as X the origin of the light. X X - When animating objects with solid textures, the textures must move X with the object, i.e. apply the same ROTATE or TRANSLATE functions X to the texture as to the object itself. X X - You can declare constants for most of the data types in the program X including floats and vectors. By combining this with INCLUDE X files, you can easily separate the parameters for an animation into X a separate file. X X - The amount of ambient light plus diffuse light should be less than X or equal to 1.0. The program accepts any value, but may produce X strange results. X X - When using ripples, don't make the ripples too deep or you may get X strange results (the dreaded "digital zits"!). X X - Wood textures usually look better when they are scaled to different X values in x, y, and z, and rotated to a different angle. X X - You can sort of dither a colour by placing a floating point number X into the texture record: X X TEXTURE X 0.05 X END_TEXTURE X X This adds a small random value to the intensity of the diffuse X light on the object. Don't make the number too big or you may get X strange results. X X Better results can be obtained, however, by doing the dithering in X a post-processor. X X X - You can compensate for non-square aspect ratios on the monitors by X making the RIGHT vector in the VIEWPOINT longer or shorter. A good X value for the Amiga is about 1.333. This seems ok for IBM's too at X 320x200 resolution. If your spheres and circles aren't round, try X varying it. X X - If you are importing images from other systems, you may find that X the shapes are backwards (left-to-right inverted) and no rotation X can make them right. All you have to do is negate the terms in the X RIGHT vector of the viewpoint to flip the camera left-to-right. X X - By making the DIRECTION vector in the VIEWPOINT longer, you can X achieve the effect of a zoom lens. X X - When rendering on the Amiga, use a resolution of 319 by 400 to X create a full sized HAM picture. X X XSection 5 - Known Bugs X There is a bug in the code to use Vector constants. The fix involves X re-working the parser quite a bit and I don't want to do that now. X X XSection 6 - Concluding remarks X X I'm sure that there are bugs in the code somewhere, but I've done my X best to remove all the bugs I could find. I also think that the object X description language needs to be re-worked. Its current syntax is a bit X cumbersome. The system could also use a good graphical interface :-). X X To that end, a conversion utility is supplied which will take in a X Sculpt-Animate 4-D object and map it into DKB's primitive TRIANGLES. X For the IBM, we have heard, but cannot confirm, there is a utility X around which will convert AUTOCAD .DXF files into Sculpt-4D files. If X anybody has it or any info about it, please contact either David Buck or X Aaron Collins. X X The IBM version is also supplied with two stand-alone TARGA-24 utilities X which were written by Aaron A. Collins. These are HALFTGA, which will X chop a TARGA-24 file in half in both X and Y dimensions for low- X resolution systems, and another file called GLUETGA which will paste X together several TARGA-24 files (of any resolution) into one. This is X principally for concatenating together several partial (interrupted) X trace output files into one. X X I would like to thank Rick Mallett from Carleton University for his help X in testing this program, for his comments and suggestions, and for X creating the data file for ROMAN.DATA - awesome! X X I would also like to thank my beta testers for all the help, bug reports, X suggestions, comments, and time spent. This version of the ray tracer X wouldn't have been possible without them. Thanks guys. X XEnjoy, XDavid Buck X END_OF_FILE if test 65462 -ne `wc -c <'Docs/dkb.doc'`; then echo shar: \"'Docs/dkb.doc'\" unpacked with wrong size! fi # end of 'Docs/dkb.doc' fi echo shar: End of archive 10 $of 10$. cp /dev/null ark10isdone MISSING="" for I in 1 2 3 4 5 6 7 8 9 10 ; do if test ! -f ark${I}isdone ; then MISSING="${MISSING} ${I}" fi done if test "${MISSING}" = "" ; then echo You have unpacked all 10 archives. rm -f ark[1-9]isdone ark[1-9][0-9]isdone else echo You still need to unpack the following archives: echo " " ${MISSING} fi ## End of shell archive. exit 0 -- Mail submissions (sources or binaries) to <amiga@uunet.uu.net>. Mail comments to the moderator at <amiga-request@uunet.uu.net>. Post requests for sources, and general discussion to comp.sys.amiga.