AMOS PD CD/amospdcd.iso/326-350/apd341/programming/tips.seq

Text File | 1991-07-19 | 7KB | 225 lines

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                               ^3T. I. P. S.

                     ^2[3(Tiny Informative Pieces Spot.)[0

                              [5^6By Len Tucker.[0

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^5 Here are just a few things that I have discovered along the way and
^5which I have found very useful.
^5 More than likely, the majority of programmers will know most, if
^5not all, of these little tips, but just in case any learners
^5(like me) are reading this, you will find these useful to know.

^4--------------------------------------------------------------------

[3^2NUMBER 1:[0

^1  Instead of using `Dec' to reduce a variable  E.G.

^7B=6
^7Dec B
^7Dec B
^7Print B

^24

^1or

^7B=50
^7For Z=1 to 10
^7Dec B
^7Next Z

^1or

^7B=50
^7B=B-10

^1Try using the add command like so:-

^7Add B,-2

^7or Add B,-10

^1Both of which do the same thing, but in less lines! (It also saves
^1wear and tear on the fingers!)

^2 The saving is obvious with the `For Next Loop' version but not so
^2obvious with the B=B-10 version. It seems that the add command is
^2much faster so use it as often as you can.

^4------------------------------------------------------------------

[3^2NUMBER 2:[0

^6  When you want to change a numeric variable (A,SCORE,LIVES,Etc)
^6to a string variable, for printing with the `Text' command
^6there is a space inserted at the begining of the string, this is
^6because when a computer sees a numeric variable, it could be one of
^6two things, either a positive or a negative, so it precedes every
^6number with a space in case it becomes a negative "-".

^6E.G.

^7SCORE=4532
^7SCORE$=Str$(SCORE)
^7Print SCORE$

^2 4532

^6 The leading space can cause you display troubles so it is better to
^6get rid of it.

^6 The way I used to do it was:-

^7SCORE=4532
^7T$=str$(SCORE)
^7SCORE$=Mid$(t$,2,Len(t$))
^7Print SCORE$

^24532

^6 Now I use a command I spotted in the compiler manual `-' it seems
^6this was in all versions of AMOS but not mentioned!

^6 Using this new(?) command the above routine would look like:-

^7SCORE=4532
^7SCORE$=Str$(SCORE)-" "
^7Print SCORE$

^24532

^6 This little command does not stop there! It will strip ALL
^6occurances of the character inside the inverts from the target
^6string!!

^6 E.G.

^7A$="The cat sat on the mat"
^7B$=A$-" "
^7Print B$

^2Thecatsatonthemat

^7A$="The cat sat on the mat"
^7B$=A$-"at"
^7Print B$

^2The c s on the m

^6 This could be very useful if handled properly.

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[3^2NUMBER 3:[0

^5  Sometimes in a game you need to dump certain Bobs or Sprites from
^5the Sprite bank. An easy way to do this is use the undoccumented
^5command (yet another!) called Del Bob. Let's say that you have 30
^5Bobs in your Bank and for some reason you want to dump the Bobs
^5numbered from 15 to 25 in order to bring back some memory. Perhaps
^5these bobs have already performed their function and are now
^5obsolete, so are a waste of memory, it is very easy to get rid of
^5them with:-

^7Del Bob 15 To 25

^2Now Bob 26 becomes 15 and so on.

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[3^2NUMBER 4:[0

^1 Supplied by[3 ROD PASCOE[0 some of you will find the Dos numbers very
^1useful.^2 Thanks Rod!

^4 This tip is for the more advanced programmer, as it can cause the
^4machine to Guru if not used with discretion. I have tried it on
^4several programs, and it seems to work O.K.

^1 The following routine allows you to call and execute a non Amos
^1program from inside Amos e.g. PPmore, Diskmaster etc.
^1 Its limits are amount of available memory and the support files
^1needed to run the program.

^2 Let's use PPmore as an example. PPmore needs the PowerPacker ARP
^2library in the libs dir to work.

^7 Amos To Back
^7 COM$="PPmore"
^7 Dreg(0)=Varptr(COM$)
^7 Dreg(1)=0
^7 Dreg(2)=0
^7 A=Doscall(-222)
^7 Amos To Front

^2 This will execute and run PPmore, once you kill PPmore, you're taken
^2back to AMOS.

^1 Use LEFT AMIGA-A keys to toggle between the two.

^4 This is very handy if you have a large `help' file to display as it
^4saves writing a routine to display it, BUT beware of copyright
^4problems, any program which calls a copyright program will not be
^4eligable for licenseware!!!!!

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^2[3NUMBER 5:[0

^1 If you've been having Compiler problems, like I have, then this tip
^1will solve one of them.

^6 Sometimes after a program has been compiled, you'll find that the
^6mouse will only move across 2/3rds of the screen, which is no good if
^6you need to click on buttons on the other 1/3rd of the screen.

^6 An easy way around this is to put in  Limit Mouse. For NTSC screens
^6this is from 128,50 to 438,249  and for PAL screens 128,43 to
^6438,294. This completely cures the problem.

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^2[3NUMBER 6:[0

^1 This is the answer to another compiler bug. If you remember, one of
^1the older versions of RAMOS had to have a default screen opened. The
^1Compiler has the same problem, so either get the Compiler to open a
^1default screen for you, or do it in your program.

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^2[3NUMBER 7:[0

^2 A simple way of centring text.

^6 If you want to centre a piece of text on the screen using the Text
^6command, try this.

^7 A$="This is centred."        ^1- put your text in the " "
^7 L=len(A$)*8                  ^1- the 8 assumes you are using the Amos
                                ^1default font.
^7 Text160-(L/2),10,A$          ^1- Assumes you have a normal 320 wide
                                ^1screen. If not, replace the 160 with
                                ^1your screen width divided by 2.

 ^2This easily centres text and will give you neater displays.

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^1 That's it for this issue, I hope that you find the above tips useful.
^1Do not forget, if you have any tips or hints that could help the
^1learners among us PLEASE send them in, they might be of use to
^1someone, so don`t be mean with your knowledge spread it about a bit!
^1You will feel better for it!!

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