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ANIMATE.DOC Tuesday, March 6, 1990 4:10 pm Page 1 Documentation for ANIMATE Overview ANIMATE creates and displays animated movies on IBM- compatible personal computers by reading one or more files containing a sequence of Tektronix 4010 (Tek4010) monochrome graphics. Movies are limited in length only by the capacity of the user's hard disk. For the user who knows C, functions supplied with ANIMATE can be embedded into the user's own PC graphics programs to make movies of whatever graphics those programs create. Those movies can then be viewed with ANIMATE. Table of Contents Overview, table of contents, and copyright . . . 1 Hardware requirements . . . . . . . 2 Software needed to complement ANIMATE . . . . 2 Files which comprise the ANIMATE package. . . . 3 Glossary . . . . . . . . . . 4 Installing ANIMATE . . . . . . . . 6 Using ANIMATE to construct and view a movie . . . 6 Plotting Tektronix graphics onto a rasterized background 7 Editing ANIMATE.PAR and "script" files . . . . 8 If you have trouble with ANIMATE . . . . . 11 Optimizing ANIMATE's performance . . . . . 11 Comments on ANIMATE's Tektronix emulation . . . 12 Modifying ANIMATE . . . . . . . . 13 Compiling ANIMATE . . . . . . . . 14 Bugs in Turbo C . . . . . . . . 15 References. . . . . . . . . . 16 Acknowledgments. . . . . . . . . 16 Copyright 1990 by Jon Ahlquist, Department of Meteorology B-161, Florida State University, Tallahassee, Florida 32306-3034, USA. Telephone: (904) 644-1558. Internet address: ahlquist@metsat.met.fsu.edu (ahlquist@128.186.5.2) This document and the files listed herein may be freely copied without charge, provided copyright notices are left intact. All software and documentation is provided "as is" without warranty of any kind. Development of this material was sponsored by NSF grant ATM- 8714674. ANIMATE.DOC Tuesday, March 6, 1990 4:10 pm Page 2 Hardware requirements to run ANIMATE ANIMATE requires an IBM-compatible PC with a hard disk and a register level compatible EGA, VGA, or monochrome Hercules graphics board. The only way to find out whether your graphics board is suitable is to try ANIMATE. Unfortunately, many older "clone" graphics boards do not meet all the requirements for true register level compatibility. Video boards compatible with Hercules monochrome graphics at the register level are available in the U.S. by mail order for under $100. More expensive but more powerful are boards like the Everex EVGA board, which supports Hercules monochrome, EGA, VGA, and a number of other modes. Such boards require a multi-sync monitor to display all their modes. Only the 640 by 350 pixel, 16 color mode of EGA/VGA graphics and Hercules monochrome graphics are supported by ANIMATE because these are the only two standard graphics modes used on IBM PCs that offer video "double buffering" (see the glossary). Since most Tektronix graphs will be generated on a mainframe computer and then transferred to a microcomputer running ANIMATE, an important factor is the time it takes to send the graphics file(s) from the mainframe to the microcomputer. For movies that contain more than a few frames of graphics, a 9600 baud connection between the microcomputer and mainframe is almost essential. A Local Area Network (LAN) like Ethernet is helpful in this regard. A telephone line may be too noisy, unless error correcting file transfer software is used; but such software running with a 1200 baud modem would be very slow. If you know C, you may decide to write some or all of your graphics directly in Turbo C and thereby avoid the transmission time between mainframe and micro. If so, you can use the program in file "makemovy.c" as an example of how to proceed. Software needed to complement ANIMATE If you generate Tek4010 graphics using a mainframe or minicomputer, you will need communications software so that your microcomputer can "capture" the graphics generated by the other computer. This software is not supplied with ANIMATE, but it is widely available. Since Tek4010 graphics commands are composed of standard ASCII characters, any communications software that can capture an ASCII file will be suitable; the package need not have any graphics capabilities at all. For example, Procomm, a common, low cost, shareware communications program, can capture a Tek4010 file because it can capture any ASCII file. A copy of the latest version of Procomm with documentation on disk can be purchased for $35 from Datastorm Technologies, Inc., P.O. Box 1471, Columbia, MO 65205. Users of TCP/IP, i.e. Internet, can acquire public domain NCSA Telnet software with documentation on disk for a $20 handling fee from: NCSA Telnet for the PC -- Orders, 152 Computing Applications Building, 605 E. Springfield Ave., Champaign, IL 61820. Telnet software does NOT work with a modem and telephone line; it works only with a TCP/IP network. ANIMATE.DOC Tuesday, March 6, 1990 4:10 pm Page 3 Files which comprise the ANIMATE package ANIMATE.DOC This documentation. ANIMATE1.C Source code for function main() of ANIMATE. ANIMATE2.C Source code for auxiliary functions for ANIMATE, including functions to save and display rasterized images. These functions can be inserted into your own Turbo C programs. ANIMATE.PRJ Project file. ANIMATE.EXE Executable version of ANIMATE. ANIMATE.PAR Parameter file configured for EGA graphics and Tek4010 graphics. ANIMATE.HER Hercules monochrome version of ANIMATE.PAR. If you have a Hercules monochrome graphics board, rename ANIMATE.PAR to ANIMATE.PAE, then rename ANIMATE.HER to ANIMATE.PAR. MAP.TEK Tek4010 plot file containing a short movie consisting of a few world maps from a satellite's perspective. MAP.SCR Script file for showing the example movie with different colors than those specified in ANIMATE.PAR. MAKEMOVY.C Example program showing how a file of rasterized images can be created directly using the graphics in Turbo C. The program also shows the difference between single and double buffering of images. MAKEMOVY.PRJ Project file for MAKEMOVY.C. GRAFSUPP.C Supplemental graphics files used by MAKEMOVY.PRJ. Some or all of the functions in this file may be useful for your own Turbo C graphics programs. GRAFSUPP.H Header file to accompany GRAFSUPP.C. GRAFDEMO.C Demonstration program which calls the routines in GRAFSUPP.C. Does not make a movie but runs with any graphics mode supported by Turbo C. GRAFDEMO.PRJ Project file for GRAFDEMO.C. TESTPIC.C Program to create a file in Tektronix 4010 format. If you wish to modify ANIMATE, you must have version 2 or newer of Borland's Turbo C. This is available inexpensively by mail order or through your local dealer. Educational customers can purchase Turbo C at especially attractive prices direct from Borland; call Borland's sales office at (408) 439-1064 and ask for Educational Sales. ANIMATE.DOC Tuesday, March 6, 1990 4:10 pm Page 4 Glossary Knowledge of the following computer graphics terms is essential to understanding the operation of ANIMATE. The definitions also include extra information specific to ANIMATE. PIXEL means "picture element." Computer text and graphics are composed of hundreds of columns and hundreds of rows of tiny rectangular "pixels." The precise number of pixels in a screen depends on the video mode you are using. Hercules monochrome graphics have 720 columns by 348 rows of pixels for a total of 250,560 pixels per screen, while high resolution EGA graphics (medium resolution VGA graphics) have 640 rows by 350 columns for a total of 224,000 pixels per screen. A Hercules pixel is either off or on, i.e. dark or lit. An EGA pixel can be any of 16 different colors chosen from a palette of 64 colors. VECTOR GRAPHICS are constructed by drawing a collection of line segments. Vector graphics may be monochrome or color. Usually, only a small fraction of the total number of pixels are involved in vector graphics. IMAGES are pictures which are more complicated than just a set of lines. For example, a very young child draws stick figures to represent objects; these are vector graphics. As the child matures, the child's drawing will include shading. Shaded regions cannot be represented accurately using line segments. Such pictures are called images. RASTERIZED IMAGES are like television pictures. An image is created by defining every pixel on the screen. Any picture displayed by an IBM-compatible PC is a rasterized image, because every pixel is defined (although many are often set to be the background color). ANIMATE stores rasterized images for its movies rather than staying with the more compact files that hold Tektronix vector graphics for two reasons: (1) an IBM-compatible PC can load a rasterized image faster than it can draw a complicated vector graphics plot, and (2) the rate at which a movie of rasterized images is shown is independent of the complexity of the images, because every pixel is always loaded. DOUBLE BUFFERING of image input means that you are viewing one picture stored in one part (one "page") of a graphics board's memory while the next image is being loaded into a second page of video memory. When this next picture is ready, then it is displayed. That leaves the first page of video memory free for loading the third picture, etc. With double buffering, you see only complete images and flickerless animation. Without double buffering, you see images being painted onto the screen or flicker. ANIMATE does not use double buffering when emulating a Tektronix terminal so that you will see the images being drawn, but it does use double buffering for showing movies, i.e. replaying rasterized images. To demonstrate single versus double buffering, I have included program "MAKEMOVY." Even modern Basic allows double ANIMATE.DOC Tuesday, March 6, 1990 4:10 pm Page 5 buffering with its SCREEN command. Microsoft's QuickBasic works fine, but Borland's Turbo Basic SCREEN command has a bug that prevents proper use of the second page of video memory for at least EGA graphics. Remember, only Hercules monochrome and the 640 by 350 pixel mode of EGA/VGA graphics offer double buffering. CGA and the other VGA modes cannot double buffer. BIT PLANES refer to a memory system used to store the color of each pixel. Let's say that each pixel has N bits available to denote its color; with EGA/VGA 16 color graphics, N=4. If bit planes are used, as they are with EGA/VGA graphics, there are N "planes" of memory. The first bit plane holds the rightmost (least significant) bit of each pixel. The next bit plane holds the next most significant bit of each pixel, etc. until we reach the N-th bit plane which holds the N-th bit of each pixel. When ANIMATE operates in EGA/VGA mode, it must know how many of the four bit planes the user wishes to use. All necessary information for a monochrome image can be stored in one bit plane. Two bit planes provide four colors; three bit planes, 8 colors; four bit planes, 16 colors. PALETTE is the name given to the color table that relates the 4 bits reserved for each EGA pixel with the 6-bit integers that represent the various possible EGA colors. 4 bits represent numbers between 0 and 15, while 6 bits represent numbers between 0 and 63. Therefore, only 16 of the possible 64 EGA colors can actually be used in any given palette. 64 colors are possible because each pixel can contain three primary colors (red, green, and blue) and three secondary colors (light red, green, and blue). See Wilton (1987) for a few more details, but so far I have not figured out to decode an arbitrary 6 bit integer into a combination of "normal" and "light" reds, greens, and blues. The problem for me lies with colors that involve the high 3 bits, i.e. color numbers greater than 7. The table below shows the standard EGA assignment of colors to base 10 pixel values. Pixel Color number (base 10) Pixel Color number (base 10) value and color value and color 0 0 black 8 56 dark gray 1 1 blue 9 57 light blue 2 2 green 10 58 light green 3 3 cyan 11 59 light cyan 4 4 read 12 60 light red 5 5 magenta 13 61 light magenta 6 7 light gray 14 62 yellow 7 20 brown 15 63 white For example, if the value of a pixel is 7, standard EGA graphics would display it as color number 20, which looks like brown. The palette can be changed; that is, any one of the 63 possible EGA colors could be assigned to the 16 possible pixel values. This is one of ANIMATE's options that will be explained later. ANIMATE.DOC Tuesday, March 6, 1990 4:10 pm Page 6 Installing ANIMATE On your hard disc, create a directory called ANIMATE, and copy all the ANIMATE software into that directory. The disk should have several unused megabytes. You'll need that much space once you start making movies because each frame of Hercules graphics or each bit plane of EGA graphics occupies about 30 kilobytes. If you make a movie containing 100 frames of Tek4010 graphics, it will occupy about 3 MB of disk space. Don't forget to back up your ANIMATE software onto "floppy" disks for safety's sake. As provided, the parameter file ANIMATE.PAR is configured for EGA/VGA graphics using one bit plane, which is all Tek4010 graphics need. If you have Hercules monochrome graphics, you need a version of ANIMATE.PAR for Hercules graphics. To do this, you need to rename two files; enter the MS-DOS commands: REN ANIMATE.PAR ANIMATE.PAE REN ANIMATE.PAH ANIMATE.PAR If you have EGA or VGA graphics, skip those two commands, because ANIMATE.PAR is already set up for you. Just to be safe, enter TYPE ANIMATE.PAR to list the contents of the parameter file. The first line should say Hercules or EGA. (If you have VGA graphics, ANIMATE.PAR should say EGA.) Using ANIMATE to create and view a movie Type ANIMATE to invoke ANIMATE.EXE. This will call up a menu of choices followed by an alphabetical list of the files in the current directory. No more than 100 file names will be displayed. If the graphics files are not in the current directory, you may want to hit the 'c' key to change the active disk and/or directory; then type the disk and/or directory just as you would for MS-DOS. For example, if your graphics files are on the same disk as ANIMATE -- say, the "c:" disk -- but in a different directory named \MOVIES, you can enter either C:\MOVIES or \MOVIES. Note: Either upper or lower case is fine for answering any of ANIMATE's questions. As an example, we'll make a movie using the supplied file MAP.TEK, which you probably have in the same directory with ANIMATE. Select Tek4010 emulation by hitting 't.' Type MAP.TEK as the name of the first file. Type DONE as the second file name to indicate that all files have been entered. Answer no ('n') to the next question about using a rasterized background; we'll discuss that later. Answer yes ('y') to the question about sav- ing the images in rasterized form. Enter MAP.EGA or MAP.HER, depending on whether you are using EGA or Hercules graphics. (I use the suffix TEK for files that hold Tektronix plot instruc- tions, the suffix EGA for files that hold rasterized images in EGA format, and the suffix HER for files that hold rasterized Hercules images. ANIMATE does not force this convention on you, though.) Lastly, you must enter which of the Tektronix plots are to be saved in rasterized form. Enter 0 0 to save all frames. ANIMATE.DOC Tuesday, March 6, 1990 4:10 pm Page 7 At this point, you should see a sequence of maps being drawn on the screen, and you should hear your hard disk whir as it reads Tektronix plotting instructions and saves the rasterized images. After all the images have been drawn, control will auto- matically return to ANIMATE's main menu. To view the movie you have just made, hit 'r' to select rasterized replay. Enter MAP.EGA or MAP.HER as the first file name and DONE as the second. Answer no to the question about saving images in rasterized format, unless you would like to save a subsequence from this movie. When the movie starts, you should see a smooth sequence of world maps appear on your screen. If you do not see a smooth sequence of maps without flicker, then your graphics board is not register level compatible with EGA or Hercules graphics, and you are out of luck as far as ANIMATE is concerned. In any case, ANIMATE will continuously repeat a movie until the user hits the Escape key (Esc) to escape to the main menu. While the movie is running, the user can hit any one of the following keys (upper or lower case) in order to select the option described. Choice: Result: s Slower movie replay. Hitting 's' more than once makes the movie run even slower. f Faster movie replay. When a movie first starts, it is running as fast as possible, so hitting 'f' will have no effect unless 's' has been hit first. 1 Toggle single step mode on or off. (Note: 1 is the digit one, not a lower case ell.) n When in single step mode, this will display the next picture. p Toggle brief (roughly 1 second) pause at the end of movie before repeating it. Esc key Go to the main menu. Control C has the same effect. Default conditions: 1. The movie is displayed as fast as possible. 2. Single step mode is off; the movie automatically advances from one picture to the next. 3. There is no pause at the end of the movie before beginning to show the movie again. Plotting Tektronix graphs onto a rasterized background Now we are ready to explain the option under Tektronix emulation that asks whether you want your graphs plotted on a rasterized background image. Let's suppose that you want to make a movie of weather maps. Each picture will show a map and on top of that map you will plot lines and symbols that show what the weather is. We'll assume that you have already debugged your program by making a few test plots. At this point, you could do a production run of plots for ANIMATE, and everything would work fine, and you could forget about the "rasterized background" ANIMATE.DOC Tuesday, March 6, 1990 4:10 pm Page 8 option. Nonetheless, an extra step may be advantageous. It is inefficient to send the same complicated map to your microcomputer over and over again with every picture. The following procedure saves execution time, transmision time, and disc space at the expense of some of your time. After debugging, run your graphics program twice. The first time, draw one single picture that contains the constant background that you want to appear in each frame of your movie; turn off the rest of the plotting commands by converting them into comments. For the second run, turn the "background" plotting commands into com- ments, restore the other plotting commands, and produce your whole movie without a background. Send the two plot files -- one contains a single frame (the unchanging background), and the other contains as many frames as will be in your movie -- to your microcomputer, and capture them using your communications soft- ware. On the microcomputer, invoke ANIMATE. Select Tektronix emulation, and create and store a rasterized version of the background map. Next, select Tektronix emulation, and enter the file name(s) holding the mapless graphics, ending with "done." Answer yes ('y') to using a rasterized background image, and enter the name of the file that holds the rasterized version of the map. For every frame of your movie, ANIMATE will read the background map and plot the other graphics on top of it. There is also a fancier use for the rasterized background option. You can combine two or more movies into one movie by overlaying them on top of each other. To do this, generate the Tek4010 graphics for each of the movies, transmit them to your microcomputer, and capture them. Then invoke ANIMATE. For the first movie, select Tektronix emulation with no rasterized background, and store that movie. For the next movie, select Tektronix emulation, and enter the file name(s). Answer yes to using a rasterized background, and enter the name of the file that contains the first rasterized movie. ANIMATE will display the first frame of the first movie and plot on top of it the first frame of the second movie, etc. If the first movie ends before the second does, the first movie will be "rewound" and started again. This is useful if the background for your movie is a repetitive sequence. Editing the parameter file ANIMATE.PAR and "script files". ANIMATE.PAR contains all the adjustable information which ANIMATE needs to define its graphics. ANIMATE.PAR is an ASCII file which can be edited by any text editor such as the NONDOCUMENT mode of WordStar. What I call a "script" file contains the same kind of information that ANIMATE.PAR does plus the names of files containing rasterized images that you want to link together into a movie. Once you understand how to construct ANIMATE.PAR, you can build a script file by starting with the same types of information as are required for ANIMATE.PAR and ANIMATE.DOC Tuesday, March 6, 1990 4:10 pm Page 9 then following that by the file name(s) for the rasterized images you want to see. With either ANIMATE.PAR or a script file, do not use any commas; just leave one or more spaces between all entries. If you have Hercules monochrome graphics, ANIMATE.PAR should contain only two lines. The first line should say "Hercules" (without quotes), and the second line should have the x and y pixel coordinates of the point at which you want the frame number displayed when that option is selected during replay of rasterized images. 0 0 refers to the upper left corner of the screen. 719 347 is the lower right corner for Hercules graphics. 0 10 is often a good place to display frame numbers, which will place the frame numbers near the upper left corner of the screen. If you have EGA or VGA graphics, ANIMATE.PAR must contain five lines. The first line should say "EGA" (without quotes). The second line must give the number of bit planes to be handled in normal operation. Usually, this is 1. The third line must contain sixteen integers (base 10) listing the EGA colors that are to be assigned to the palette. (See the explanation of the palette in the glossary.) Do NOT separate the integers with commas; that would cause an error. (The program may not bomb, but colors will not be read correctly.) Just leave one or more spaces between the numbers. For EGA/VGA monochrome graphics, only the first bit plane is needed. I like yellow lines plotted on a blue background, and I have specified this in the supplied copy of ANIMATE.PAR, whose third line reads: 1 62 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Thus, color 1 (blue) is shown when a pixel value is 0, and color 62 (yellow) is shown when a pixel value is 1. So blue is the background color, and yellow is the foreground color. The remaining color assignments for pixel values 2 through 15 are arbitrary because those colors will never appear if only one bit plane is loaded; I have chosen color 0 (black). Another example of color assignment is given below where script files are discussed. The fourth line of ANIMATE.PAR for EGA graphics specifies the color to be used when writing frame numbers on the pictures. The color is indicated by the PIXEL VALUE to be assigned (0 through 15), NOT by the actual color number (0 to 63). In the supplied version of ANIMATE.PAR, the fourth line is 1. That means that, when frame numbers are written onto images, it will be done by assigning a value of 1 to the affected pixels. Given the color assignments indicated in the preceding paragraph, that means that the frame numbers will appear in color number 62 (yellow). The fifth line of ANIMATE.PAR for EGA graphics must contain the x and y pixel coordinates of the point at which you want the frame number to be displayed. 0 0 is the upper left corner of the screen. 639 349 is the the lower right corner. 0 10 is ANIMATE.DOC Tuesday, March 6, 1990 4:10 pm Page 10 often a good place to display frame numbers, which will place the frame numbers near the upper left corner of the screen. A script file holds a "script" for displaying rasterized images. It offers two features. One, it allows graphics mode assignments to be temporarily reset from the normal values specified in ANIMATE.PAR. Second, if more than one file contains the rasterized images for a movie, you only have to enter the file names once into this file, rather than manually type all the file names each time you want to view the movie, as you would have to do if you selected ANIMATE's option to "replay rasterized images." The first part of a script file is constructed in exactly the same way as ANIMATE.PAR. That is, if your movie uses Hercules graphics, the first line of the script file must say "Hercules" (without quotes), and the second line must give the x and y pixel coordinates where frame numbers are to be written. If your movie uses EGA or VGA graphics, a script file must start with five lines defining the EGA graphics parameters. These lines can be different than what is in ANIMATE.PAR. As an example where a script file would be nice, let's suppose that your mainframe computer has 3-D graphics routines that allow you to set the viewing angle of a plot in perspective and that you have EGA or VGA graphics on your microcomputer. If so, you have what you need to make 3-D movies using the method where you draw one eye's view in red and the other eye's view in green. You should generate Tek4010 monochrome graphics with two views of every image. All of the even numbered frames should be one eye's view and all the odd numbered frames should be the other eye's view. Your script file for ANIMATE should be some- thing like this: EGA 2 0 2 4 6 0 0 0 0 0 0 0 0 0 0 0 0 1 0 10 FILE1.EGA FILE2.EGA FILE3.EGA etc. up to a maximum of FILE10.EGA With this assignment, two bit planes will be loaded to form each image. The background will be black (color 0). The first rasterized image read will be placed into the first bit plane, and the nonzero pixels will appear in color 2 (red). The second image will be loaded into the second bit plane, and its nonzero pixels will appear in color 4 (green). In cases where a pixel is used in both bit planes, the pixel value will be 1+2=3, to which I suggest assigning color 6 because that color (not one of the standard EGA colors) is constructed by displaying both red (color 2) and green (color 4). ANIMATE.DOC Tuesday, March 6, 1990 4:10 pm Page 11 You must view such 3-D movies with special glasses. The Bulletin of the American Meteorological Society for February 1981 included a red/green viewer for 3-D pictures, or you can make a crude but adequate viewer using cardboard, red and green cellophane, tape, and scissors. I have not done much with 3-D movies other than to run the sample movie (MAP.EGA) with the script file shown above. The result is not satisfying. I suspect that the user will have to experiment for a while before good 3-D movies result. Please let me know of your successes. If you have trouble with ANIMATE The most common problem will be that Tektronix emulation works okay, but the rasterized replay does not work. Most likely, the problem lies with your graphics board. Animation on an IBM-compatible PC pushes the capabilities of graphics boards, and only some graphics boards meet all the standards of Hercules monochrome or IBM EGA graphics. Nonetheless, a few things should be checked before you consider upgrading your graphics board. 1. Double check the contents of ANIMATE.PAR. The only two supported graphics modes are EGA (or equivalently VGA) and Her- cules. If you have CGA graphics or EGA graphics with only 64KB of memory on the video board, you are out of luck. Secondly, make sure that no commas appear in ANIMATE.PAR; entries should be separated only by blanks. 2. Some video boards require that you run a program supplied by the boards manufacturer in order to set the board into a certain mode of operation. For example, normally I keep my Everex EVGA board in EGA mode (actually, in MS-DOS, I execute "EVGAMODE 5"). If I want to look at a movie of rasterized Hercules images, I must first execute EVGAMODE 23 in MS-DOS to switch the board into Hercules mode; just specifying "Hercules" in ANIMATE.PAR or in a script file is not enough. Curiously, if the EVGA board is in Hercules mode, it will correctly switch itself temporarily into EGA mode if ANIMATE.PAR or a script file calls for EGA graphics. 3. Hercules rasterized images and EGA rasterized images are different, so a movie stored in rasterized Hercules form can only be viewed with Hercules graphics; similarly, a movie stored in rasterized EGA form can only be viewed with EGA graphics. Optimizing ANIMATE's performance When ANIMATE displays rasterized images, its most time consuming task by far is loading the rasterized images into video memory from the disk file(s) where the images are stored. You can do three things to make the display as fast as possible. ANIMATE.DOC Tuesday, March 6, 1990 4:10 pm Page 12 First, if you have two or more megabytes of memory, you can set aside some of that memory as a virtual disk, also called a RAM disk. Look up DEVICE = VDISK.SYS in your MS-DOS manual. ANIMATE can read a rasterized movie very rapidly from RAM disk. Remember that each Hercules image or each EGA bit plane occupies about 30 kilobytes of memory, so you will need a lot of RAM disk for a movie of any length. Second, make sure that your disk is not storing rasterized movies in "fragmented" form. If you do not know what a fragmented file is, fragmented files are almost certainly a problem on your disk. When a file is stored on a disk, it is entirely possible that, unknown to you, the computer may crack the file into two or more pieces and store the pieces on separated parts of the disk. This is known as fragmentation. The benefit of fragmentation is that it makes usable the various "bare" spots scattered about the disk that result when old files are deleted. The disadvantage of fragmentation is that it can slow disk access because the disk head has to jump around the disk to reach all the parts of a file. There are a number of commercially available programs that rewrite files so as to eliminate fragmentation. I am familiar with three "unfragmenters": (1) Speed Disk in the Advanced Edition of Norton Utilities; (2) COMPRESS in PC Tools from Central Point Software, and (3) VOPT from Golden Bow Systems. Any of these is good. (Be warned: the "quick" option on Norton Utilities' Speed Disk does not remove fragmentation and can actually create additional fragmentation; instead, use "file unfragment.") The first time you run an unfragmenter on your disk, it may take 10 minutes or more to straigthen up your files. Thereafter, it will only need 10-20 seconds to straighten up things if you run it regularly. My AUTOEXEC.BAT file invokes an unfragmenter every time I boot my computer. Third, the data transfer rate between your disk and your computer may not have been optimized by the computer manufacturer, specifically, the "interleave factor" may not be optimal. This is a "guts level" parameter that users normally do not alter; however, a program called SpinRite from Steve Gibson Research can optimize the interleave factor as well as do other disk maintenance tasks. Byte magazine (Nov 1988, pp. 237-239) has reviewed SpinRite. See also the hard disc maintenance packages reviewed in Byte, Jan 1990. Comments on ANIMATE's Tektronix 4010 emulation I coded the Tek4010 emulation based on a description of Tek4010 operation given in chapter 5 of the manual for the FlexiTek communications program marketed by Various Ware, P.O. Box 21070, El Cajon, CA 92021, telephone (619) 448-7126. Only the graphics mode of Tek4010 operation has been simulated. All other input is ignored. An important item which is not part of the Tek4010 graphics ANIMATE.DOC Tuesday, March 6, 1990 4:10 pm Page 13 language is an "end of plot" signal. I decided to terminate a plot when a "clear screen" command (ASCII characters CR FF (hexadecimal 0d 0c)) is received or when an end of file (EOF) mark is encountered in the input file. Multiple plots can and should be in a single file, even though up to ten files can be chained together by ANIMATE. The limit of 10 files could be increased by changing the definition of MAX_FILES in ANIMATE1.C, but there is little reason to do this since there is no limit to the number of plots that can be stored in a file. In other words, if you can, keep all your Tektronix plotting instructions for a movie in one file and all your rasterized images for the movie in one other file. Modifying ANIMATE Source code for ANIMATE is provided in files ANIMATE1.C and ANIMATE2.C so that you can make whatever modifications you might like. The user will no doubt think of a number of possible improvements to ANIMATE, such as: 1. Emulation of a color Tektronix terminal. The Reference Guide for version 3 of the commercially marketed Macintosh VersaTerm-Pro communications package contains Chapter X: Appendix (pp. 288-299) seems to provide enough information regarding the operation of a Tektronix 4105 terminal to allow someone to write at least a partial emulator using Turbo C. VersaTerm-Pro is marketed by Synergy Software, 2457 Perkiomen Ave, Reading, PA 19606, telephone (215) 779-0522. 2. Allowing movies to run backwards. 3. Expanded use of script files. When I first tried writing an animation program I used Turbo C's getimage() and putimage() functions, but they are too slow for animation. Direct reads and writes from the graphics board are necessary, and that is why register level compatibility is required of your graphics board. I would be pleased to hear of your ideas and improvements. Before you do much work on improving ANIMATE, I would suggest sending me a message. That way, I can let you know whether I or somebody else might already be working on the improvement you have in mind. If you are willing to share your improvements with me, please take care to write clean, heavily documented code. Anything less is hard to maintain and almost impossible for another programmer to figure out. I probably will not be very quick to add additional features to ANIMATE. I will certainly keep your suggestions in mind and I hope that ANIMATE will be improved, especially by other users, but my job as a meteorology professor dictates that I spend the majority of my time doing research and teaching, not programming applications. I wrote ANIMATE to display the results of my ANIMATE.DOC Tuesday, March 6, 1990 4:10 pm Page 14 research, and it took a LOT of time, because I was also learning C and PC graphics at the same time. I am basically satisfied with ANIMATE in its present form, although I certainly would like to add a Tek4105 color emulation mode, but I feel that I do not have the time to do that at present. I need to use ANIMATE as a research tool, not work on it as an end in itself. If you have Internet, you might use FTP every so often to sign onto the anonymous FTP account on unidata.ucar.edu (user = anonymous, password = guest) and check directory /ahlquist/animation to see whether any bugs have been discovered and corrected or whether a new version may be available. Compiling ANIMATE If you wish to recompile ANIMATE, you will need version 2 or newer of Borland's Turbo C. "Far" pointers are needed by _read() and _write() when rasterized images are placed into or read from the graphics board. Therefore, I have compiled ANIMATE using Turbo C's "compact" memory model. (Under Turbo C's Options menu, select Compiler, then Model Size, and Compact.) Under Options, Compiler, Code Generation, I turned off "OBJ debug information," which trims about 6 kilobytes from ANIMATE.EXE. Nonetheless, leave OBJ debug information "on" if you start modifying ANIMATE, because the integrated debugger can be a great help. The project file ANIMATE.PRJ contains instructions for Turbo C on how to create ANIMATE.EXE. The project file should contain: ANIMATE1 ANIMATE2 GRAPHICS.LIB EGAVGA.OBJ HERC.OBJ The latter two files are created easily using Borland's BGIOBJ utility; see Borland's Turbo C Reference Guide for details. With compilation of the present version of ANIMATE2.C, you will encounter two warnings that say that variable num_bit_planes is not accessed in save_Herc_raster() and display_Herc_raster(). This is okay. Hercules monochrome graphics do not use bit planes, but num_bit_planes is included so that the arguments to the Hercules routines are the same as those to save_EGA_raster() and display_EGA_raster(), which do need bit plane information. This makes it possible to use function pointers save_raster() and display_raster() to point to the appropriate routines. This avoids several "if" statements that would have to check for the graphics mode. You will also encounter a warning saying Tek4010() should return a value; it does, but all the return statements are within the function and none appears at the end. ANIMATE.DOC Tuesday, March 6, 1990 4:10 pm Page 15 Bugs in Turbo C While writing ANIMATE, I encountered the following bugs in Turbo C. A letter from Borland indicates that these bugs have not been corrected as of 18 February 1990. ANIMATE works around these bugs. 1. In Hercules graphics mode, cleardevice() should clear only the active page of video memory, but the Hercules version of cleardevice() clears both pages of video memory and resets the visual page to 0 (the first page of video memory); at least the active page is not reset. Occasionally, I have also had some trouble clearing the screen in EGA mode after accessing bit planes, but Borland graphics were not designed to be bomb-proof to attacks by a user who putzes with the guts of the graphics. (See point 2 below.) 2. Writing text to the screen in graphics mode using outtextxy() after accessing a bit plane does not always work correctly with EGA graphics, so I write to the screen twice, and the second time is ok. 3. For speed reasons, replay of rasterized images is done with unbuffered input/output (IO). ANSI standards implement unbuffered IO by calling fopen(), then setbuf(fp, NULL) to set the buffer size to zero, followed by use of fread() and fwrite(). I tried to do this, both for compatibility with ANSI standards and to simplify the program. The problem is that Turbo C's IO absolutely crawls if done according to ANSI standards; it is MUCH slower that buffered input. Since the ANSI standard is not feasible, I have used _read() and _write() for unbuffered IO, because they are Turbo C's fastest IO routines. ANIMATE.DOC Tuesday, March 6, 1990 4:10 pm Page 16 References In addition to the two Borland Turbo C manuals (User's Guide and Reference Guide), the references I used when writing ANIMATE are listed below. For more exposure to double buffering of images, I suggest that you look at the sample program MAKEMOVY.C. Schildt, Herbert, 1985: C Made Easy. Osborne McGraw-Hill, Berkeley, California, 292 pages. (No graphics are discussed, just the basics of C. There is also a version of this book specifically for Turbo C called Turbo C Made Easy.) Schustack, Steve, 1985: Variations in C. Microsoft Press, Bellevue, Washington, 344 pp. (Intermediate level guide to C; a good second book after one is familiar with the basics of C. No graphics.) Wilton, Richard, 1987: Programmer's Guide to PC & PS/2 Video Systems. Microsoft Press, Redmond, Washington, 531 pages. (This is the most comprehensive book available on programming IBM PC graphics. To understand this book, you need to know assembly language, which I do not, so almost all of it is too technical for me. Fortunately, Borland's Turbo C has functions to perform many graphics functions, and Tom Yoksas of Unidata showed me how to do the crucial reads and writes directly from the video board which make animation possible. You should be aware of this book's existence, but you can probably get along fine without it unless you want to know the register level operations of PC graphics.) Acknowledgments: ANIMATE was written to help display results of research funded by NSF grant ATM-8714674. Not only did this grant pay my salary during part of the development of ANIMATE, it also purchased some of the computer equipment on which the development was done. Tom Kitterman of the Florida State University Meteorology Department patiently answered many of my questions involving register level operations with graphics. During the summer of 1989, Carla Engel, an undergraduate summer mathematics student under NSF applied mathematics sponsorship, helped document the bugs which I had found in Turbo C. Tom Yoksas who works at the Unidata Project Office of the University Corporation for Atmospheric Research in Boulder, Colorado showed me how read and write directly from the graphics board, which makes animation possible.