From: "M Bailey" <mark AT shire DOT globalnet DOT co DOT uk>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Ultra-newbie needs ultra-help
Date: Fri, 5 Feb 1999 18:55:56 -0000
Lines: 121
Message-ID: <79fes4$ghs$1@newnews.global.net.uk>
References: <19990204071933 DOT 10404 DOT qmail AT hotmail DOT com> <36B9E7D5 DOT 855F0B98 AT cableol DOT co DOT uk>
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To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Reply-To: djgpp AT delorie DOT com

I might be wrong, but I thought the Allegro documentation states that you
need to set the color depth before setting the screen mode and that the
default mode is already 8-bit ?


Allens wrote in message <36B9E7D5 DOT 855F0B98 AT cableol DOT co DOT uk>...
>The only problem I can think of is that allegro does not support your
>graphics card.  What card is it?
>
> Peter Allen
>
>
>Stephen Gordon wrote:
>>
>> I am trying to learn how to program in DJGPP. I have only just started.
>> I have a
>> P200 with Win95, and have downloaded DJGPP v2.8.1 and Allegro v3.1 (as
>> well
>> as RHIDE). My problem is that my program, which is supposed to display
>> the
>> Mandelbrot set on screen in 256 colors, only does it in 16. The source
>> is below as
>> it's fairly short, and the strange thing is that it works properly on my
>> other more
>> powerful computer which also runs Win95.
>> Any suggestions? (I can't find this in the FAQs)
>>
>> Stephen Gordon
>>
>>  PS. I don't know any assembler.
>>
>> Source code below
>> ________________________________________________________________
>>
>> #include "allegro.h"
>>
>> int main()
>> {
>>    PALLETE pallete;
>>    BITMAP *m_map;
>>    RGB temp;
>>    int x, y, c;
>>    float a, b, aa, bb, m, n;
>>
>>    allegro_init();
>>    install_keyboard();
>>    set_gfx_mode(GFX_AUTODETECT, 800, 600, 0, 0);
>>    set_color_depth(8);
>>
>>    m_map = create_bitmap(800,600);
>>
>>    /* first set the pallete to black to hide what we are doing */
>>    for (c=0; c<255; c++){
>>        pallete[c].r=0;
>>        pallete[c].g=0;
>>        pallete[c].b=0;
>>        }
>>
>>    pallete[1].r=255;
>>    pallete[1].g=255;
>>    pallete[1].b=255;
>>    set_pallete(pallete);
>>
>>    /* draw the M-set onto the memory-map */
>>    for (y=0; y<600; y++){
>>        for (x=0; x<800; x++){
>>            a=b=c=aa=bb=0;
>>            m=(2*(x-399.5)/399.5)-.5;
>>            n=(2*(y-299.5)/299.5);
>>            while (((a*a+b*b)<4)&&(c<256)){
>>                  aa=a*a-b*b+m;
>>                  bb=2*a*b+n;
>>                  a=aa;
>>                  b=bb;
>>                  c++;
>>            }
>>            putpixel (m_map, x, y, c);
>>            if (y==(int)(0.75*x))
>>                  putpixel (screen, x, y, 1);
>>        }
>>    }
>>
>>    blit(m_map, screen, 0, 0, 0, 0, 800, 600);
>>
>>    /* fill our pallete with a gradually altering sequence of colors */
>>    for (c=0; c<64; c++) {
>>       pallete[c].r = c;
>>       pallete[c].g = 0;
>>       pallete[c].b = 0;
>>    }
>>    for (c=64; c<128; c++) {
>>       pallete[c].r = 127-c;
>>       pallete[c].g = c-64;
>>       pallete[c].b = 0;
>>    }
>>    for (c=128; c<192; c++) {
>>       pallete[c].r = 0;
>>       pallete[c].g = 191-c;
>>       pallete[c].b = c-128;
>>    }
>>    for (c=192; c<256; c++) {
>>       pallete[c].r = 0;
>>       pallete[c].g = 0;
>>       pallete[c].b = 255-c;
>>    }
>>    /* animate the image by rotating the pallete */
>>    while (!keypressed()) {
>>       temp = pallete[255];
>>       for (c=255; c>0; c--)
>>   pallete[c] = pallete[c-1];
>>       pallete[0] = temp;
>>       set_pallete(pallete);
>>    }
>>
>>    return 0;
>> }
>>
>> ______________________________________________________
>> Get Your Private, Free Email at http://www.hotmail.com