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[the following is an ascii version of the paper given out at the developer's forum this past May, 1992, and was the companion to the Totally Insane (tm) CD accompanying tom davis' and paul haeberli's presentation. all references to the Totally Insame (tm) CD itself however have been supplanted with references to the developer's toolbox CD structure -- ratitor ] Graphics Utility Tools and Libraries CD Paul Haeberli Silicon Graphics Computer Systems Abstract The Iris Graphics Library supports interactive drawing of lighted 3-D geometry, but sometimes the interface provided by the GL is not the most convenient or general. For example, filling concave polygons or describing lighting can be complex and unpleasant tasks. This paper describes libraries and tools that are available to solve many common graphics problems. These tools handle problems like triangulating concave regions for rapid display, drawing character strings using geometry, creating beveled and extruded shapes, automatic generation of triangle meshes, environment mapping 3-D geometry, dithering rgb images and drawing anti-aliased characters. Introduction A variety of graphics tools will be discussed. Here's a brief overview: Several image related library functions will be described, along with various conversion programs. Then special image processing tools for environment maps will be introduced. After image related stuff, it's on to geometry. We have a simple geometry format and a set of programs that can display or modify this geometry. The complete source code to these programs is included. Next it's outline fonts. There's a paint program for generating outline fonts and tools for transforming outline descriptions into filled characters using triangle meshes. A library that draws anti-aliased characters is provided, along with tools for reading Adobe Type1 fonts and generating Type 3 fonts. Then, a few miscellaneous things are discussed, like a nice interface for viewing geometry, general dithering code and easier GL lighting. In addition to this, theres a whole bunch of other insane stuff. You'll just have to read the rest of the paper to find out. I can't get everything into the stinking introduction! Acknowledgements The software described here was developed with the help of many other people. Kurt Akeley wrote the auto meshing functions & the geometry capping example (located in toolbox/src/exampleCode/cap). Ivan Bach wrote the DPSGLX demo (/toolbox/src/exampleCode/GLX/dpsglx). Gavin Bell and Thant Tessman wrote the original virtual sphere interface for viewing geometry. Forest Baskett kindly let us spend time on this. David Brown made his face available in digital form. Derrick Burns developed the concave polygon triangularization library (toolbox/src/haeberli/lib/libtri.a). Nancy Cam provided the a image warping application called tiepoint (toolbox/bin/tiepoint). Simon Carter at Abekas provided code for converting between digital video format and rgb space (toolbox/src/haeberli/abekas). Kathy Chaix cleverly tricked us into organizing this CDROM. Tom Davis contributed calc - a simple calculator (toolbox/src/exampleCode/calc), generic - a generic application template (toolbox/src/swtools/generic), geometer - a program for creating geometric proofs (toolbox/src/tutorials/geometer), 3Dmodeling - a library for creating 3-D geometry (toolbox/src/exampleCode/3Dmodeling), and zip - a FAST editor for the IRIS (toolbox/bin/zip). Dave Larson provided funding for publishing the CDROM. Sam Leffler wrote the TIFF image library (toolbox/src/haeberli/libtiff). David Maynard developed the audio mesh application - amesh (toolbox/src/demos/audio/amesh). Reuel Nash developed iso, an iso-surface rendering program (toolbox/src/exampleCode/iso). Dave Ratcliffe helped us get this source together. Seth Teller wrote the font painting program and several of the other font tools. Doug Voorhies developed mtex, a program to help make texture maps from scanned images (toolbox/src/haeberli/mtex). This paper refers to various source files and programs. These files are located on the "Totally Insane Graphics Tools and Utilties" CDROM. Image Stuff By an image, we mean a rectangular array of pixels. On the Iris, we currently use our own SGI image file format to store image data. This format is used for screen dumps and for printing. A program called "ipaste" displays an Iris image on the screen. The Iris image library is called "libimage.a" and it is installed in /usr/lib on all Iris workstations. You can look in the the directory /toolbox/src/haeberli/libimage if you want to see the implementation of the actual image library. Normally you will only need to call a few different routines in the image library to read or write an Iris image file, or you can make a single call to read all the pixels in an image into an array of longs. Take a look at the program imgtools/rectimg.c as an example of how to read pixel data from an image file in a easy way. It's easy to write simple filters that operate on Iris images. The source to a number of image processing programs can be found in the imgtools directory. Some of these tools read and write other image file formats, while others operate on Iris image files. A simple program that saturates an Iris image can be found in imgtools/saturate.c A few image tools deserve special note. The programs "fromyuv" and "toyuv" convert between Abekas digital video images and Iris image files. These tools can be used to record images from the Iris on a device that supports digital video data, or to make an image that can be displayed on the Iris. Routines that generate and read digital video data can be found in libgutil/abekas.c A program called "gendit" supports general dithering of Iris images. It takes an RGB image as input and writes out an RGB image with a smaller number of colors. You can specify on the command line how many levels of red, green and blue may be used in the output image. This program uses the code in libgutil/gendit.c to perform an ordered dither. This dithering technique can be used to display good looking continuous tone images in the overlay planes or the underlay planes. At times you may need to resize an Iris image. This can be done with the program "izoom". The source can be found in imgtools/izoom.c You can specify a floating point scale factor for resizing in x and y. You can also specify the kind of filtering to use when resizing. The program "imgtools/scope" can be used to roam around very high resolution images quickly, examine actual pixels values in an image and determine exact pixel locations. The program "movie" lets you view a series of images as a movie loop. Finally "scrsave" can be used to save an image from the screen as an Iris image file. Take a look at the function savewindow in libgutil/glstuff.c. It shows how to execute scrsave from inside a graphics program to save the current window as an image file. Tiff Library Support An important industry image file standard is the TIFF image format. Eventually we will be using TIFF as our standard image file format. You can find complete source to a library that reads and writes TIFF in public/tiff. There are also two Iris programs in imgtools called "totiff" and "fromtiff" that can convert Iris images into tiff images and back. Environment Map Tools Environment or Reflection mapping is a technique that uses texture mapping to simulate the smooth shading of reflective surfaces. It can be used to create very nice shading of more diffuse surfaces as well. The program objtools/spin can be used to draw an object with environment mapping. A variety of tools for creating and manipulating environment maps are provided in the envtools directory. The primary format of an environment map is a single Iris image file that has a 3 by 2 array of square images from 6 faces of a cube. Environment maps can be created in several ways. One way is to take a 180 degree fisheye picture of a scene, scan in this image and then project this onto the cubical format. The program "envtools/fromfish" does exactly this. The result of this is an image like those in the "envmaps" directory. These environment map images can be processed using the many of the Iris image tools. But when it comes to doing area processes, special tools are needed. The program "envreduce" zooms a cubical environment map down by a factor of two, while the program "envexpand" zooms a cubical environment map up by a factor of two. These two programs can be used in sequence to blur cubical environment maps. In the IRIX 4.0 release, the VGX and Indigo machines have support for using the normal of surfaces to provide texture map coordinates for reflection mapping. The format used for environment mapping is not a cubical format but a spherical format. The program "envtools/sphereenv" can be used to convert an environment map in cubical format into a spherical format. When doing this you MUST use the "-s" option so a reflective sphere is rendered. Other environment map creation tools are also available in the "envtools" directory. A collection of processed spherical environment maps can be found in the directory called "128env". These can be used on machines that support texture mapping to render very nice looking surfaces. We are actively collecting interesting reflection maps. If you would like to contribute some, please let me know. Texture Map collection A small collection of 128x128 texture maps can be found in the directory called "128tex". We are actively collecting interesting texture map images that are 128x128 or 256x256. If you make some really neat textures, we would really like to include them in our collection! A Simple Geometry Format Over the past years we've had a lot of discussion about file formats for geometry. It's a difficult and complex topic. At one end of the scale you could use an interpreted language and at the other end of the scale you could just use a data structure for storing geometry. Languages have the advantage that they are very flexible and may be extended easily. A simple geometry data structure has the advantage that you can easily define operations on objects. I have a simple format that I've been using for polygonal objects. The library source that suports this format is in libgutil/sgiobj.c and libgutil/sgiobjgl.c. Each sgo object is either a list or quadrilaterals, a list of triangles, or a list of triangle meshes. Each vertex in one of these objects has a 3D position, a normal and 3 values that are either a RGB color or a texture map coordinate. A collection of sgo objects is provided in the "objects" directory. Various tools for operating on these objects can be found in the "objtools" directory. The program "spin" reads in one of these objects and lets the user control the scale and orientation of the object using a virtual sphere user interface. Another tool "totri" transforms objects that are lists of quads into triangle list objects. The program "tomesh" converts a list of triangles into a triangle mesh object. These tools use various functions from libgutil that support a simplified interface to describing shading, automatic triangle mesh generation and efficient drawing of geometry. The program "subdiv" subdivides a list of triangles object to insure that no triangle in an object are larger than some specified size, while "explode" translates all vertices in the direction of their normal. The program "sterrend" in the objtools directory shows how to display geometry using Red-Green Stereo, while "warpgeom" applies a deformation to a geometric object. Font Tools I've developed a binary file format for storing fonts. These fonts can either be polygonal outlines (font.of), spline outlines (font.sp), or triangle meshes (font.mf). The basic support for this file format is in libgutil/objfnt.c, while libgutil/charfill.c has code that creates and draws anti-aliased bitmaps of a outline font. A collection of outline fonts is provided in the "fonts" directory . But new ones can easily be created using the programs in the "fonttools" directory. A program called "paintfont" allows you to paint each character to define an outline font. Each painting is autotraced to create polygonal outlines. The code that converts an image into outlines is in libgutil/stream.c. Once polygonal outlines are created, the program "adjustfont" can be used to adjust the character spacing and character widths in the outline font. You can see what anti-aliased renderings of the characters look like by running "charfill". Adobe Type1 fonts can be converted into polygonal or spline format by using "fromtype1". If you want to draw characters using triangle meshes, the program "meshfont" converts a font.of file into a font.mf file automatically. The program "bevelstring" can be used to create 3D geometry from a string of text. This program uses the library code in libgutil/path.c to provide support for describing and filling concave regions. If you want to make PostScript fonts that can be used with DPS or a laser printer, the program "makepsfont" can be used to generate a Type3 font and an AFM file. Audio Analysis Example Amesh (toolbox/src/demos/audio/amesh) is a program that makes audio visible by plotting a real-time history of sequential power spectra computed from an audio input stream. FFT-fu, Audio-fu; Paul-Bob sez: "Check it out". Making "Paintings" from Images The "impression" directory has tools for creating painted representations of scanned images interactively. To give this a try, type "make demo" in the "impression" directory. The other tools in this directory can be used to manipulate paintings described by a list of brush strokes. The "autopaint" directory has tools for automatically creating paintings. To try this out, type "make demo" in the "autopaint" directory. A Little Paint Program for the Iris The "imp" directory has the source for a fun little paint program for the IRIS. It does all its drawing into memory and then copies the result onto the screen. You can zoom the canvas image up to do detailed work. To try this out, cd to "imp" and type "make demo". This program uses the "libcan" library to blend brush strokes onto the canvas. Enhance Images Interactively The "enhance" directory has the source for an image enhancement program that let's you enhance a source image by choosing an image processing operation, and then picking an image from a range of processed images. To give this program a try, type "make demo" in the "enhance" directory. LEEP Projection for VR Display The program in "leep" implements the LEEP projection in software. This maps a 140 degree viewing angle into a circle, as required by the optics provided by LEEP. To try this out, cd to "leep" and type "make demo". Use Compression to Display Movies Take a look in the "movie" directory . There is a program called "mkmov" for compressing a series of images and another one called "expmov" to display a compressed movie. To see it go, you guessed it, just type "make demo". Prepare Texture Map Images Look in the "mtex" directory. This contains an image processing application that massages scanned images for use as texture maps. It performs common operations such as color or contrast correction, cropping, and sharpening, plus unusual functions needed for texture maps. These include making edges match so the image can be used as a tile, "homogenizing" a texture to eliminate splotchiness and gradations, and synthesizing an alpha channel from the color information. Miscellaneous Goo The programs above rely on a collection of library routines that are in lib, libcan and libgutil. These libraries support the virtual sphere user interface, automatic triangularization of complex concave areas, automatic triangle mesh generation, drawing of anti-aliased characters, conversion from RGB to CMYK space, and more. There is also a vector and matrix library, functions to help make it easier to use GL lighting and routines to generate PostScript images and drawings. An Apology In keeping with the informal nature of this conference, we began preparing this document at 2:30 for a 5:00 deadline, so there are still a few things we didn't have time to describe. This gives YOU the opportunity to explore the following directories on your own: Check out Tom Davis's stuff in toolbox/src/exampleCode/calc, toolbox/src/swtools/generic, toolbox/src/tutorials/geometer, toolbox/src/exampleCode/3Dmodeling and toolbox/bin/zip. Then look at toolbox/src/exampleCode/cap, compexp, toolbox/src/exampleCode/GLX/dpsglx, toolbox/src/printers/dpsprint, toolbox/src/exampleCode/iso, styline, toolbox/bin/tiepoint, tools, and tools/tritest. If you are interested you may want to compile the libraries and tools and take a look at the README files provided. Good luck, and have fun!