Subject: The -Color-Scroller- By: James Collett (Professor) A Member Of: VIRTUAL INFINITY Date: April `94 Address: Park View Farm, Carlton, Nr Nuneaton, Warks, CV13 ODA Internet: s6005146@brookes.ac.uk Mono Account: bcc This Screen Is Public Domain ============================ This means it may be freely copied and distributed *providing* the following four files remain TOGETHER and UNALTERED: scroller.txt - this file scroller.gfa - main screen tables\st_pal.gfa - palette generator for 8MHz tables\falc_pal.gfa - palette generator for 16MHz Also On Disk ============ The following two files should also be with the screen: tables\st_pal.dat - palette data file for 8MHz tables\falc_pal.dat - palette data file for 16MHz However, if either of these two files are missing, don`t panic! Programs are included to allow palettes to be created and customised (discussed shortly). Running The -Color-Scroller- ============================ The first thing that`s needed is a copy of GFA Basic 3. If you don`t have it, WHY NOT?!? Assuming you have GFA 3, the -color- -scroller- only runs in ST low res compatible (320 * 200 * 16 color). The main program, scroller.gfa, has (hopefully) been specially written to run on both 8MHz machines (e.g. ST) and 16MHz machines (e.g. FALCON). As explained when the screen starts up, I`ve not yet figured out a way of determining the processor speed which works on ALL ATARI machines. So at the minute YOU have to tell the program what speed you have (by pressing '8' for 8MHz or 'space' for 16MHz). [If you`re not sure, run both versions and see which looks best!] After showing the credits, the program should load the appropriate palette data file and run the scroller. The 8MHz scroller consumes some 1800 colors a second, and the 16MHz version burns up no fewer than 3600 colors a second - not exactly environmentally friendly!! ÿÿÿÿ If the program reports a "File Not Found" error then you`ll have to create the palette data files (discussed shortly) before you can run the main program. If you don`t like the color scheme or get bored of it, you may like to customise the palette data files (discussed shortly). Bugs / Incompatibility ====================== The 8MHz version has been tested on an STe, and the 16MHz version has been tested on a FALCON. It #may# be that the timing`s out on other ATARIs (TT, MegaST, etc) despite the fact their 680x0 runs at 8MHz or 16MHz. This may be due to blitters, co-processors, resident programs, etc. If a screen doesn`t work on your machine then PLEASE report the bug (too fast, too slow, etc) and your setup (8MHz processor, 8MHz blitter, etc) to the screen`s author! Creating And Customising Palette Tables ======================================= Both versions of the -color-scroller- 'cycle', or scroll, palettes up the screen. The 8MHz version uses 6 palettes (numbered 0 to 5) and the 16MHz version uses 12 palettes (numbered 0 to 11). These palettes are not calculated in realtime as it`s difficult to calculate "pretty" color schemes!! Instead the 'palette tables' are stored in external data files: the 8MHz scroller uses a 6-palette data file (tables\st_pal.dat) and the 16MHz version uses a 12-palette data file (tables\falc_pal.dat). Two additional GFA programs are included, in the tables\ folder, to allow the respective palette data files to be created (if missing) and customised - i.e. to allow palette data files to be 'generated'. Each of the 6 (or 12) palettes consists of a 'BASE COLOR' (for example medium red with a tinge of blue: &401) to which you add 'RANDOM INTENSITY' to produce a range of shades. For example adding a random intensity of 4 to a base of &401 will generate shades with reds between 4 and 7, greens between 0 and 3 and blues between 1 and 4. In other words shades between &401 and &734. The list of base colors for the palettes is contained at the end of the table generator program. Each palette`s base color 'description' should be of the following form: DATA red_on,red_base, green_on,green_base, blue_on,blue_base There should be as many base color descriptions as there are palettes - i.e. tables\st_pal.gfa should contain 6 data lines (one for each palette) and tables\falc_pal.gfa should contain 12 data lines (one for each palette). Each base color description should contain six values as illustrated above: the first two for the red COMPONENT, the second two for the green component and the last two for the blue component. Each component_base should be in the range from 0 to 7 (inclusive). Each component_on value acts like a "switch", and should either be set to 0 if you wish the component off or 1 if you wish the component on. If you`re unsure about setting the base colors or random intensity, the best thing to do is EXPERIMENT! Once you`ve set the base colors and random intensity, simply run to generate a palette data file for the main -color-scroller- (ensuring the data file is saved in the tables\ folder). You may also like to save the actual generator program, to save your base color and random intensity settings. Important: ~~~~~~~~~~ If the sum of any component base (for any palette) and the random intensity is greater that 8, then it is likely you`ll have intensities greater than 7 in your data file. At best this may not look "pretty" (!), at worst in may be incompatible with your machine. If you have an STfm compatible (3 bit) palette, for best results always ensure 'the sum' cannot exceed 8. If you have an STe compatible (4 bit) palette, for best results always ensure 'the sum' cannot exceed 16. And Finally =========== Although there is no financial charge for the program, support appreciated. You can support in two ways: 1) by distributing the programs to everyone you know, ensuring all files remain together and unaltered, 2) feedback: all comments, queries, error / incompatibility reports, ideas, suggestions, etc are welcome - both positive and negative. My postal and E-mail addresses are previously listed. ---END---