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 09:31:33 1995.msg

Internet Message Format | 1995-10-02 | 4KB

Received: from svcs1.digex.net (svcs1.digex.net [204.91.197.224]) by mail1.access.digex.net (8.6.12/8.6.12) with ESMTP id JAA19789;  for <[e-mail]> ; Tue, 26 Sep 1995 09:31:32 -0400
Received: (from daemon@localhost) by svcs1.digex.net (8.6.12/8.6.12) id FAA09219 for amos-out; Tue, 26 Sep 1995 05:09:39 -0400
Received: from mail1.access.digex.net (mail1.access.digex.net [205.197.247.2]) by svcs1.digex.net (8.6.12/8.6.12) with ESMTP id FAA09216 for <[e-mail]>; Tue, 26 Sep 1995 05:09:38 -0400
Received: from tlti.tokem.fi ([e-mail] [193.64.110.2]) by mail1.access.digex.net (8.6.12/8.6.12) with ESMTP id FAA04212;  for <[e-mail]> ; Tue, 26 Sep 1995 05:08:47 -0400
Received: (from mystic@localhost) by tlti.tokem.fi (8.6.12/8.6.9) id LAA07713; Tue, 26 Sep 1995 11:06:58 +0200
Date: Tue, 26 Sep 1995 10:59:39 +0200 (EET)
From: Petri Hakkinen <[e-mail]>
Subject: Re: Help me!
To: Ben Wyatt <[e-mail]>
cc: [e-mail]
In-Reply-To: <[e-mail]>
Message-ID: <Pine.3.87.9509261038.A7411-0100000@tlti>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Content-Transfer-Encoding: QUOTED-PRINTABLE
Status: RO
X-Status:





On Tue, 26 Sep 1995, Ben Wyatt wrote:

> Greetings [e-mail], you wrote some text on the subject Hel=
p
> me!, and now I'm going to answer it.
>=20
> 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 par=
t of
> M>=20
> 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>=20
> 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>=20
> 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 function=
s
> M> work
> M> in the other direction.).
> M> Finally, it must be fast enough, even if not just like the Circle comm=
and
> M> (or Fcircle by Turbo extension!).
>=20
> AT LAST! An interesting problem!
>=20
> This should do it:
>=20
> Procedure _PART_OF_CIRCLE[R,A,B,X,Y,STP]
>    Gr Locate X+Sin(A)*R,Y-Cos(B)*R
>    For N=3DA+STP To A+B Step STP
>       Draw To X+Sin(N)*R,Y-Cos(N)*R
>    Next N
> EndProc

If you want speed you should put Sin & Cos into arrays. Floating point
calculations are really sssslllooooowwwwww.....

Example:

dim si(360),co(360)
for t=3D0 to 360:si(t)=3Dsin(t)*256:co(t)=3Dcos(t)*256:next

and the draw part should be:
Draw To X+(SI(N)*R)/256,Y-(CO(N)*R)/256
                               =20
the /256 is done with bitshifting so it don't take much of time,
at least when compiled. Btw. isn't AMCAF's Turbo draw much faster?
If you have AMCAF (or Turbo extension) use it instead of amos!

Or even better, you can precalculate Sin(N)*R values with every possible
N and R but it takes lots of memory... If you really want the speed...=20

Pete

- Petri H{kkinen / [e-mail] -
=20
>=20
> Where:
>   R=3DRadius
>   A=3DStart angle
>   B=3DDegrees to rotate
> X+Y=3DCentre of circle
> STP=3DAccuracy (small=3Dslow but accurate, large=3Dfast but less accurate=
)
>     Use about 4-5, depending on the size of the circle.
>=20
> Bye  _________________________________
>     /                                 \
>     > Ben Wyatt - [e-mail] <
>     \_________________________________/ =A91995 Very Interesting Signatur=
es
>=20