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ü AMOS Tutorial - IFF Fonts ------------------------- þ Part 1 - What is an IFF font? Part 2 - How does it work Part 3 - Creating an example font Part 4 - Creating your own fonts ù This tutorial has been typed out by Andrew "Mushroom" Kellett, of Mushroom PD (C) March 1996. All rights reserved. If you wish to use this article in any other disk magazine, you must first get my permission in writing. I must also receive a FULL copy of the magazine that it appears in. ú If you would like to get in touch with me about Extreme AMOS, Mushroom PD or any other AMOS related matter, you can get in touch with me at the below address. If you decide to telephone, please do it after 7pm, when I am not as busy, and no later than 11pm, after all, we all need our beauty sleep! The address is : ÿ û Andrew "Mushroom" Kellett Mushroom PD 32 Castleton Crescent Gamesley Glossop Derbyshire SK13 9TH ENGLAND ü Telephone (01457) 857502 E-Mail: mush@sneech.demon.co.uk ý All letters sent to me will be replied to as soon as possible. As well as this tutorial, there are other tutorials available : û Creating AMOS Graphic Equalizers Creating Simple Databases Creating an AMOS Tracker demo Identifying different music formats in AMOS (62K!) ÿ þ If you would like any of the above tutorials, then you can send me an SAE and a disk. If you fill the disk full of your own AMOS games and utilitys, either compiled or in source code for inclusion in the library, then you need not include the SAE, as I will send you the stuff back. Alternatively, you can exchange a disk of your own programs for a Mushroom disk in the library. Remember to state the Mushroom disk number when ordering. ù Have you written any AMOS tutorials which you would like included in Extreme AMOS? They can be of any kind of subject, as long as it is AMOS. It could be anything from the use of a simple command, right through to a large programming diary you have completed. The address to send all of your ASCII files, along with any source code that accompany's the tutorial, is listed above. You will receive a FREE copy of the first issue that your tutorial appears in. ÿ ú PART 1 ~~~~~~ ü What is an IFF font ? þ I daresay you have loaded and played a game, where there is a nice attractive font that appears on the screen, to display either the instructions or maybe the hi-scores. With a hi-score table, there are endless possibilities for the names that you enter into it. One way of doing this, is to read a font stored on the disk, but displaying these can be a bit slow, so the need for an IFF font is called. A IFF font is a screen full of letters and numbers, that can be called at any time from within the program, to be displayed anywhere on any screen. These characters are all coloured in the same style as the rest, to classify the screen as an IFF font screen. This screen is then packed, and is saved to the disk along with the program. IFF fonts use a lot less space than if you just had lot's of screens with the IFF font displayed as instructions, or everything placed in a sprite bank to be displayed later on. ÿ þ There are 2 kinds of IFF font, the first being a simple "Square" layout, where each of the characters has the same height and width. These are the easiest kinds of font to work with. The second kind of font is a non-proportional font, in which the width or height of the font can change with each of the characters. These fonts take a little more time to prepare, but still look just as good. Fonts can range from simple 3 or 4 pixel squared images, right through to a full screen in size. The number of possibilities that can be acheived from the font is endless. ÿ ú PART 2 ~~~~~~ ü How does an IFF font work ? þ An IFF font is really very simple to use, in any kind of program. The routines which I have supplied you will demonstrate how easy it is to install a font into your program. An IFF font is read from a grid in memory. Each grid space can either be a "Square" font, or each piece can vary in size. The program creates an array with all the X and Y coordinates for each of the possible pieces, which is called by the other routines. There is also another part to the array which contains the width of all the different characters available, which is more usefull when the font is non-proportional. Let me try and give you an example. Let's say that you decided to use an array called FONT. The program would create 5 offsets from that array, FONTX, FONTY, FONTXX, FONTYY, AND FONTS. FONTX and FONTY represent the top left hand coordinates of the top of the character in the list. FONTXX and FONTYY hold the bottom right-hand coordinates for ÿ þ the character. FONTS hold the width (in pixels) of the character just defined. Another way of doing this, is to eliminate FONTS completely, and use the algorythym FONTXX-FONTX, but the way I have described is easier to follow. The next step, is to create a string of all the available characters in your font. Let's say "ABCDEFGHIJKLMNOPQRSTUVWXYZ". Now, when the INSTR command is used against the letter we are looking for, it will return with the number inside the string. Say you were looking for the letter "D", then INSTR would return with 4. So, it would use the SCREEN COPY FONTX(4),FONTY(4),FONTXX(4),FONTYY(4) To destination.. and paste the letter "D" into place. It is highly important that the string containing all the letters is typed in the same way the information is entered into the array, otherwise the letters will come out different than what you have requested. The routines I have developed, have been coded to allow you, the user, to apply as little AMOS knowledge as possible. All you have to do, is assign the POSX and POSY graphics coordinates on the screen, for where you want the text to go, and the string you wish printed. If you ÿ þ decide to use the centring routines, then the POSX coordinate is not needed, as the program will automatically work out the position for you. All the routines in ALL my fonts use the same kind of parameters for different functions. Some of the routines have scrollers, and centering routines, which can easily be called in your programs. The variables I tend to use the most are : û TEX$ - The string to be drawn on the screen POSX - The X coordinate of the destination of the font POSY - The Y coordinate of the destination of the font SC$ - The text which is to be scrolled across the screen NUM - The character being drawn, according to the array _SCREEN - The screen number to be drawn on þ I have eliminated the need to add loads of parameters onto a procedure call, saving space in the text buffer, so the program runs off the CURRENT settings of all the variables called. It is important that you make these values GLOBAL, or SHARED, otherwise they will be ÿ þ read as 0 by the routine. Any other variables are called from within the routine, and are not really all that important. If centering the piece of text, then you only need assign the POSY value with the true number, and the TEX$ string to be displayed. _SCREEN does not need to be changed more than once unless you are working on a different screen number. If using the scroller, you can determine how you would like to leave the routine. I usually place a small routine in the code which will allow me to leave the routine if the mouse button is pressed, and I have taken this out of some of the examples. Remember, CTRL+C will break you out of the program, and back to the editor. If you define the statements as global values, you can also maintain the values of the last drawing, which is handy when on an options screen for example. You could have "Quit? (Y/N)", and then when the key is pressed, you could recall the draw routine and print the character, before moving onto the next piece of text. ÿ þ One thing which I like about IFF fonts, is the fact that they can be used in any screen mode, providing the font has enough colours, and does not contain more than the desired screen resolution. This means that you can fit more text onto a line if you go into hi-res mode, or less, more detailed characters on the screen if you decide to opt for a lower resolution. Because the program uses SCREEN COPY, the results it produces are almost instantaneously, especially if there is not much to copy. If the font is small and are quite a few lines to be done, then it may take a couple of seconds, but it is even faster when compiled. The only drawback, is that you can't merge the font onto an already-drawn background, as it copy's the black bits from the font screen, over to the destination screen. In order to get round that problem, you will need to use GET BOB, and PASTE BOB, which is slower to use than SCREEN COPY. ÿ ú Part 3 ~~~~~~ ü How to create an example font that works þ OK then, I am now going to create a simple program, which will first create a non-proportianate font. Also included, is a scroll routine, which when activated, will scroll a piece of text across the screen using that IFF font. ý Load and run EXAMPLE_01.AMOS þ As you can see, the font scrolls across the screen. If the screen was not in DOUBLE BUFFER mode, it would flicker and jump quite badly. You can also see all the DATA statements, which make up this kind of font. Now, I think it is time for a proportional font. ý Load and run EXAMPLE_02.AMOS þ This is a nice 16 colour font, which means that it can also be ÿ þ used on a hires screen, with some good results. Look at the DATA statements, and see how I built up the size array, using the TEMPA and TEMPB arrays alongside it. Again, I have chosen to use the scroller routine. Now, I think it is about time I demonstrated how simple it is to use the _CEN and _DRAW routines from within a font. The next example uses the same font as in example 2, but will centre a few words. If you look at the listing in which you need to actually perform the task, you will see that you only need to assign 2 values before actually running - The text string to be printed, and the vertical position of the text. The draw routine is called from within the centering routine, but you can actually move this around, and call it seperate of the routine. ý Load and run EXAMPLE_03.AMOS þ See, dead simple. The hardest part of the entire thing, is defining the font to create. Once the routines are installed, it is so easy to use, in all kinds of screenmodes. This fonts work in Hires. ÿ ú Part 4 ~~~~~~ ü How to create your own IFF fonts! þ Hmm, you do need a paint package to do this, although I am sure that there is a program somewhere in the library that will actually make the data statements for you. If not, I shall get onto making one very soon. First of all, you will need to place all of the possible characters onto a single screen, without them lapping over each other's boundary's, otherwise you will get ghosted letters appearing on the screen. It is best that you use a single screen, to any size you need, as you would need to create another element in the font arrays in order to determine which screen you are going to copy from. Now you will need to go into personal paint, or any other paint package that you have, which will allow you to magnify the picture, and show the X and Y coordinates of the screen. Now, write down a list of all the possible characters available, and get the coordinates by ÿ þ following these instructions : ü Proportional fonts ~~~~~~~~~~~~~~~~~~ û Simply write down each horizontal coordinate of each letter, by letting the crosshairs of the mouse overlap onto the first pixel on the top, and the left-hand side of the letter. Write down the coordinates. Now do the same for the bottom right of the character, but ensure that the crosshairs are NOT overlapping onto any of the pixels. You must also write down the 4 coordinates for all the characters on the left hand side of the screen, and use an array similar to what I used, with the across number of letters going across, and the down going down in the loop. Also make a note of the width of the character in pixels, to be used instead of NINES() ü Non-Proportional fonts ~~~~~~~~~~~~~~~~~~~~~~ û Unlike the above, you must write down all 4 coordinates for each ÿ û letter, and also the width (in pixels) of each letter, so the program can add the space accordingley. Take the coordinates using the same method as above, and draw a line from the left hand side of the char, to the right, and the screen should tell you how many pixels it takes (before you let go of the mouse). Pressing UNDO should remove the line, unless you clicked on something else first. Once you have all of your coordinates, you can place them into DATA statements like I did, spacing them out, with each letter being on one line during testing, to iron out any small bugs that you may have overlooked. When you know it is working correctly, you can then reduce the number of lines. ù Well, I think that just about covers it. As you know, every month I give away new IFF font programs, so you should never be short of an IFF font to use in your own programs. Most of the IFF fonts were drawn by people other than myself, yet the program was written by me, so remember that in your credits should you decide to use any of my routines. ÿ ù If you want to know more about any other AMOS subject, then why not drop me a line at the above address. I also have other tutorials available (all with source) which cover a whole array of different subjects : û Graphic Equalizers Tracker Tutorial Prt. 1 Tracker Tutorial Prt. 2 Databases Prt. 1 Databases Prt. 2 IFF Fonts ø You can get any of these tutorials by sending an SAE and a disk, or 4 first class stamps, to me at the address above. If you are sending a disk, then why not fill it with some AMOS PD so I can place it in the library. All letters will be replied to as soon as possible. ÿ û If you would like to contribute any articles to Extreme AMOS, then include them on the disk as well. Remember, any articles I use, you will receive a FREE copy of the first issue they appear in. I would prefer it if you sent AMOS articles, but other things such as reviews etc. are welcome. I would especially like things like programming diaries, and routines, which are explained in detail, to cover special FX on the screen, or some other form of really usefull routine. The list of possibilities is endles !! ú [Andrew "Mushroom" Kellett] ÷ EOF