svgalib use on debian 11 i386
lazarus / 39-Graphics

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tan9p · 2022-03-31 15:56

I copy the following program to draw the Mandelbrot set.
The Source:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i program
Mandelbrot; {$ASSERTIONS+} uses crt,graph; type        complex=record 
              re:real;                im:real;        end; operator
*(a:complex;b:complex)c:complex;begin        c.re := a.re*b.re -
a.im*b.im;        c.im := a.im*b.re + a.re*b.im;end;operator
+(a:complex;b:complex)c:complex;begin        c.re := a.re + b.re;    
  c.im := a.im + b.im;end; var        z,c:complex;       
gd,gm,i,j,k:integer;begin        gd := Detect;        gm :=
m1024x768;        InitGraph(gd,gm,'');       
Assert(graphResult=grOk);        c.re := -0.75;        c.im := 0;    
  for i:=-300 to 300 do                for j:=-200 to 200 do         
     begin                        z.re := i/200;                     
 z.im := j/200;                        for k:=0 to 200 do            
          begin                                if
(sqrt(z.re*z.re+z.im*z.im)>2) then                                   
   break                                else                         
              z := (z*z) + c;                        end;            
          PutPixel(i+300,j+200,k);                end;        readln; 
      CloseGraph;end.
and I installed the svgalib on my debian 11.
But It only displayed Using VGA mode,svgalib 1.4.3,no drawing.
How can I handle it ? thanks

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MarkMLl · 2022-03-31 17:16

Are you able to run any svgalib test programs with full resolution?

MarkMLl

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tan9p · 2022-04-01 01:10

No. all of them displayed the same screen. Using VGA mode,svgalib
1.4.3
both the pascal and C test program.

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MarkMLl · 2022-04-01 06:36

Quote from: tan9p on April 01, 2022, 03:10:35 amNo. all of them
displayed the same screen. Using VGA mode,svgalib 1.4.3
both the pascal and C test program.

In that case if test programs supplied as part of svgalib don't work
properly it's an operating system issue.

I didn't realise anybody still used svgalib any more except possibly
for embedded stuff. It was fairly common when I started uing Linux in
about '94...

MarkMLl

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tan9p · 2022-04-01 09:33

Thanks.
I found the following information in
https://www.freepascal.org/faq.var
5.6
Quote链接器为什么找不到 "vga"？
这个错误通常是这样的：

                 Free Pascal Compiler version 3.0.x [xxxx/yy/zz] for
i386
                 Copyright (c) 1993-2008 by Florian Klaempfl
                 Target OS: Linux for i386
                 Compiling test.pp
                 Assembling test
                 Linking test
                 /usr/bin/ld: cannot find -lvga
                 test.pp(6,4) Warning: Error while linking Closing
script ppas.sh 5 Lines
                 compiled, 0.2 sec
           
此错误不是 FPC 或 FPC 本身的安装错误，是在 UNIX 安装中缺少 Svgalib 库。请使用你喜欢的包管理器工具安装所需的库

Is it out of date?
On Windows,the above Source works well， and How Can I get the same
result on linux?

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MarkMLl · 2022-04-01 09:37

Code: [Select]/usr/bin/ld: cannot find -lvga

Fix that.

However the FIRST thing to do is determine whether the current
combination of svgalib and Linux can display the resolution you want.

Somewhat later: https://tracker.debian.org/pkg/svgalib shows that
svgalib was removed from Debian in 2013 at which point it corresponded
to https://launchpad.net/debian/+source/svgalib/1:1.9.25-3 which is
presumably one of the development versions from
http://my.svgalib.org/svgalib/

The only possible reason you might have for trying to use this is if
you're working on a standalone system which doesn't have one of the
standard GUIs (i.e. desktop etc.). Even then, I'd be surprised if it
was an easy job unless you could get hold of the same hardware that
people were using for it in 2013: and even then it might turn out to
be challenging even for an experienced user.

You might do better starting off with something like
https://sourceforge.net/projects/doublefractal/ or alternatively this
forum's advanced search facility with the results ordered by date...
there's been fairly recent discussion of Mandelbrot generation.

MarkMLl