EnigmA Amiga Run 1995 November/EnigmA AMIGA RUN 02 (1995)(G.R. Edizioni)(IT)[!][issue 1995-11][Skylink CD].iso/earcd/program/amos/amoslist.lzh/AMOSLIST/[e-mail]_Tue Sep 26 05:11:23 1995.msg

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X-Mailer: ADMail 1.5 Copyright 1995 S.T.Brown
From: [e-mail] (Ben Wyatt)
To: [e-mail]
Subject: Re: Help me!
Status: RO
X-Status:

Greetings [e-mail], you wrote some text on the subject Help
me!, and now I'm going to answer it.

M> I have to solve a problem in AMOS Pro programming: is there anyone who can
M> help me??
M> I explain the problem.
M> I must (or better, I want to) do a procedure to draw on a screen a part of
M>
M> a
M> circle. Is there any extension to do it??
M> Otherwise I have to use sin() and cos() function, but these are relly very
M> slow.
M> The procedure should be like:
M>
M> Procedure PART_OF_CIRCLE[R,A,B]
M>      where R is the radius, A the value of the angle in degree
M>      and B is how many degrees the line is long
M>      (sorry for my English, can you understand me? :-(( )
M> End Proc
M>
M> Unfortunately, becouse of all the structure of the program, the screen is
M> in
M> Hi resolution, but you have just to use R/2 in the sin() part.
M> But the biggest matter is that the 0 degree must be at 12 o'clock, 90
M> degrees at 3 o'clock and so on in clockwise (instead the trig functions
M> work
M> in the other direction.).
M> Finally, it must be fast enough, even if not just like the Circle command
M> (or Fcircle by Turbo extension!).

AT LAST! An interesting problem!

This should do it:

Procedure _PART_OF_CIRCLE[R,A,B,X,Y,STP]
   Gr Locate X+Sin(A)*R,Y-Cos(B)*R
   For N=A+STP To A+B Step STP
      Draw To X+Sin(N)*R,Y-Cos(N)*R
   Next N
EndProc

Where:
  R=Radius
  A=Start angle
  B=Degrees to rotate
X+Y=Centre of circle
STP=Accuracy (small=slow but accurate, large=fast but less accurate)
    Use about 4-5, depending on the size of the circle.

Bye  _________________________________
    /                                 \
    > Ben Wyatt - [e-mail] <
    \_________________________________/ �1995 Very Interesting Signatures