Nox-Rhea WiKi

Hello! This is Denthor here with the 5 part of the ASPHYXIA VGA Trainer Series : The Scrolling Saga. I have had many requests for information on scrolling, so I decided to make it this weeks topic. Note that I do make reference to my recently released program TEXTER5, which should be available from wherever you get this message. (Note to Sysops : If you put the trainer series up on your boards, please add WORMIE.ZIP and TEXTER5.ZIP as they both suppliment this series)

By the way, sorry for the delay in the appearance of this part. Tests, projects and a few wild days of sin at the Wild Coast all conspired against the prompt appearance of this part. Also note I need more input as to what I should do future parts on, so leave me mail.

If you would like to contact me, or the team, there are many ways you can do it :

            1) Write a message to Grant Smith in private mail here on the Mailbox BBS.
            2) Write a message here in the Programming conference here on the Mailbox (Preferred if you have a general programming query or problem others would benefit from)
            3) Write to ASPHYXIA on the ASPHYXIA BBS.
            4) Write to Denthor, Eze or Livewire on Connectix.
            5) Write to :  Grant Smith
                           P.O.Box 270 Kloof
                           3640
                           Natal
            6) Call me (Grant Smith) at 73 2129 (leave a message if you
                  call during varsity)

NB : If you are a representative of a company or BBS, and want ASPHYXIA to do you a demo, leave mail to me; we can discuss it.

NNB : If you have done/attempted a demo, SEND IT TO ME! We are feeling quite lonely and want to meet/help out/exchange code with other demo groups. What do you have to lose? Leave a message here and we can work out how to transfer it. We really want to hear from you!

If you have ever seen a demo, you have probably seen some form of scrolling.

Our SILKYDEMO has quite a nice example of scrolling. What it is is a long row of text moving across your screen, usually from right to left, eg :

                                       H     : Step 1
                                      He     : Step 2
                                     Hel     : Step 3
                                    Hell     : Step 4
                                   Hello     : Step 5
                                  Hello      : Step 6

etc. etc. See the program attatched for an example of scrolling.

Usually, letters. Most groups put greetings and information in their 'scrollies', as they are termed. You can also scroll and entire screen using the scrolling technique. Scrolling your text is a hell of a lot less boring then just having it appear on your screen. Unfortunately, 'scrollies' have been used so many times in demos they are wearing a bit thin, so usually they are accompanied by a cool picture or some nice routine happening at the same time (In our SILKYDEMO we had a moving checkerboard and colour bars going at the same time).

The theory behind scrolling is quite easy. Let us imagine that we are scrolling a 16×16 font grabbed by TEXTER () across the top of the screen (ie. 320 pixels) As we know, the VGA screen starts at zero at the top left hand part of the screen, then counts up to the right to 319, then goes back to the left hand side one pixel down at 320. (See Tut 1) This means that a 16*320 scroller takes up the space 0 to 5119 on the screen. In ascii this looks like this :

            (0)   .                                    .  (319)
            (320) .                                    .  (639)
                            "             "           "
           (4800) .                                    .   (5119)

Simple enough. Now what we do is we put down the first Y-line of the first character onto the very right hand side of the screen , like so :

              For loop1:=1 to 16 do
                Putpixel (319,loop1-1,font['A',1,loop1],vga);

This will draw some stuff on the very right hand side. Your screen should now look like this :

            (0)   .                                   X.  (319)
            (320) .                                   X.  (639)
                            "             "           "
           (4800) .                                   X.   (5119)

Next, we move each line one to the left, ie :

              For loop1:=0 to 15 do
                Move (mem[VGA:loop1*320+1],mem[VGA:loop1*320],320);

This scrolls the screen from right to left, which is the easiest to read. To scroll the screen from left to right, swap the +1 onto the other side of the command. Also, to increase the size of the portion scrolled, increase the 15 to however many lines from the top you wish to scroll-1.

After this move, your screen will look like this :

            (0)   .                                  X .  (319)
            (320) .                                  X .  (639)
                            "             "           "
           (4800) .                                  X .   (5119)
                                                      ^
                                                Note this space

What you then do is draw in the next line on the right hand side, move it, draw the next line, move it etc. etc. Tah-Dah! You have a scrolly! Fairly simple, isn't it?

To scroll up or down is also fairly simple. This can be used for 'movie credit' endings (I once wrote a little game with a desert scrolling down with you being a little robot on the bottom of the screen). The theory is this : Draw the top line (or bottom line) then move the entire screen :

             Move (mem[vga:0],mem[vga:320],63680);
                       { 64000 - 320 = 63680 }

For scrolling down, or :

             Move (mem[vga:320],mem[vga:0],63680);

For scrolling up. You then draw the next line and repeat.

Because of the simplicity of coding in a scrolly, most demos have one. It is usually best to have something extra happening on the screen so that the viewer doesn't get too bored, even, as I say, if it is only a really nice picture.

The University of Natal, Durban, Science Dept., now has 10 new 486's! This is a great boon, as now I can program nice routines during frees (even though I am a Commerce Student (Shhhhh) ). I can now use those previously wasted hours that I spent socialising and making friends coding instead

I suggest you get a copy of TEXTER, for coding demos with fonts, or in fact almost any graphics application, it is an amazing help, and we have used it for *ALL* our demos. (P.S. We have written many demos, but many have been written for companies and have not been released for the general public)

[
    "I'm from the Computer Inspection Agency, sir, I'm here to check your computer. Here is my identification."
    "Certainly. Have a look, I'm clean. I don't have any pirated software."
    The C-man pushes past him and sits in front of the computer. He notes the fact that the computer is currently off with a look of disdain. He makes a note on his clipboard. He boots up.
    "What is this?" he asks, pointing at the screen.
    "It's MasterMenu" stutters the man. "I wrote it myself!"
    "Do you know what the penalty is for using junk like this on a private machine?" The C-man smiles. "This is a two-month sentance in itself!"
    "I'm sorry sir! It won't happen again!"
    "I know. I'll make sure of that." He smiles again.
    The C-man runs through the hard drive, checking for illeagal software, bad programs and anti-government propaganda. 
    He notes with satisfaction that he has enough to put this weenie away for ten years, not that it mattered. He usually could just make something up.
    He comes to the last entry on the aphebetised menu tree. His hands jerk away from the keyboard. Then, tentatively, he types in the three letters of doom. 
    He looks at the man, who is backing away with wide eyes and his hands outstretched in front of him, as if to ward off a blow.
    The C-man smiles, his lips a thin, hard line.
    "Windows!"
]

Grant Smith 1:55pm 16/9/93

Cheers, Denthor

(*****************************************************************************)
(*                                                                           *)
(* TUT3.PAS - VGA Trainer Program 5 (in Pascal)                              *)
(*                                                                           *)
(* "The VGA Trainer Program" is written by Denthor of Asphyxia.  However it  *)
(* was limited to Pascal only in its first run.  All I have done is taken    *)
(* his original release, translated it to C++, and touched up a few things.  *)
(* I take absolutely no credit for the concepts presented in this code, and  *)
(* am NOT the person to ask for help if you are having trouble.              *)
(*                                                                           *)
(* Program Notes : This program presents the basic demo scroller.            *)
(*                                                                           *)
(* Author        : Grant Smith (Denthor)  - denthor@beastie.cs.und.ac.za     *)
(*                                                                           *)
(*****************************************************************************)
 
{$X+} {$R-}
Uses Crt;
 
CONST VGA = $a000;
      XSize = 16;
      YSize = 16;
 
TYPE
        Letter = Array[1..xsize,1..ysize] of Byte;
        Letters = Array[' '..']'] of Letter;
 
VAR Font : ^Letters;
 
{ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ}
Procedure SetMCGA;  { This procedure gets you into 320x200x256 mode. }
BEGIN
  asm
     mov        ax,0013h
     int        10h
  end;
END;
 
 
{ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ}
Procedure SetText;  { This procedure returns you to text mode.  }
BEGIN
  asm
     mov        ax,0003h
     int        10h
  end;
END;
 
{ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ}
procedure WaitRetrace; assembler;
  { This waits until you are in a Verticle Retrace }
 
label
  l1, l2;
asm
    mov dx,3DAh
l1:
    in al,dx
    and al,08h
    jnz l1
l2:
    in al,dx
    and al,08h
    jz  l2
end;
 
{ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ}
Procedure Pal(ColorNo : Byte; R,G,B : Byte);
  { This sets the Red, Green and Blue values of a certain color }
Begin
   Port[$3c8] := ColorNo;
   Port[$3c9] := R;
   Port[$3c9] := G;
   Port[$3c9] := B;
End;
 
 
{ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ}
Procedure PutPixel (X,Y : Integer; Col : Byte; Where : Word);
   { This puts a pixel at X,Y using color col, on VGA or the Virtual Screen}
BEGIN
  Mem [Where:X+(Y*320)]:=col;
END;
 
{ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ}
procedure LoadPal (FileName : string);
   { This loads the Pallette file and puts it on screen }
type DACType = array [0..255] of record
                                R, G, B : byte;
                              end;
var DAC : DACType;
    Fil : file of DACType;
    I : integer;
BEGIN
  assign (Fil, FileName);
  reset (Fil);
  read (Fil, DAC);
  close (Fil);
  for I := 0 to 255 do Pal(I,Dac[I].R,Dac[I].G,Dac[I].B);
end;
 
{ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ}
function Exist(FileName: string): Boolean;
    { Checks to see if filename exits or not }
var f: file;
begin
  {$I-}
  Assign(f, FileName);
  Reset(f);
  Close(f);
  {$I+}
  Exist := (IOResult = 0) and
   (FileName <> '');
end;
 
 
{ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ}
Procedure Setup;
  { This loads the font and the pallette }
VAR f:file;
    loop1:char;
    loop2,loop3:integer;
BEGIN
  getmem (font,sizeof (font^));
  If exist ('softrock.fnt') then BEGIN
    Assign (f,'softrock.fnt');
    reset (f,1);
    blockread (f,font^,sizeof (font^));
    close (f);
    Writeln ('SoftRock.FNT from TEXTER5 found in current directory. Using.');
  END
  ELSE BEGIN
    Writeln ('SoftRock.FNT from TEXTER5 not found in current directory.');
    For loop1:=' ' to ']' do
      For loop2:=1 to 16 do
        for loop3:=1 to 16 do
          font^[loop1,loop2,loop3]:=loop2;
  END;
  If exist ('pallette.col') then
    Writeln ('Pallette.COL from TEXTER5 found in current directory. Using.')
  ELSE
    Writeln ('Pallette.COL from TEXTER5 not found in current directory.');
  Writeln;
  Writeln;
  Write ('Hit any key to continue ...');
  readkey;
  setmcga;
  If exist ('pallette.col') then loadpal ('pallette.col');
END;
 
 
{ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ}
Procedure ScrollMsg (Msg : String);
  { This scrolls the string in MSG across the screen }
Var Loop1,loop2,loop3 : Integer;
Begin
  For loop1:=1 to length (msg) do BEGIN
    For loop2:=1 to xsize do BEGIN
 
      { This bit scrolls the screen by one then puts in the new row of
        letters }
 
      waitretrace;
      For Loop3 := 100 to 99+ysize do
        move (mem[vga:1+(loop3*320)],mem[vga:(loop3*320)],319);
      for loop3:=100 to 99+ysize do
        putpixel (319,loop3,font^[msg[loop1],loop2,loop3-99],vga);
           { Change the -99 above to the minimum of loop3-1, which you
             will change in order to move the position of the scrolly }
    END;
 
    {This next bit scrolls by one pixel after each letter so that there
      are gaps between the letters }
 
    waitretrace;
    For Loop3 := 100 to 99+ysize do
      move (mem[vga:1+(loop3*320)],mem[vga:(loop3*320)],319);
      for loop3:=100 to 99+ysize do
        putpixel (319,loop3,0,vga);
  END;
End;
 
 
BEGIN
  ClrScr;
  Writeln ('This program will give you an example of a scrolly. If the file');
  Writeln ('SOFTROCK.FNT is in the current directory, this program will scroll');
  Writeln ('letters, otherwise it will only scroll bars. It also searches for');
  Writeln ('PALLETTE.COL, which it uses for it''s pallette. Both SOFTROCK.FNT');
  Writeln ('and PALLETTE.COL come with TEXTER5.ZIP, at a BBS near you.');
  Writeln;
  Writeln ('You will note that you can change what the scrolly says merely by');
  Writeln ('changing the string in the program.');
  Writeln;
  Setup;
  repeat
    ScrollMsg ('ASPHYXIA RULZ!!!   ');
  until keypressed;
  Settext;
  freemem (font, sizeof (font^));
  Writeln ('All done. This concludes the fifth sample program in the ASPHYXIA');
  Writeln ('Training series. You may reach DENTHOR under the name of GRANT');
  Writeln ('SMITH on the MailBox BBS, or leave a message to ASPHYXIA on the');
  Writeln ('ASPHYXIA BBS. Get the numbers from Roblist, or write to :');
  Writeln ('             Grant Smith');
  Writeln ('             P.O. Box 270');
  Writeln ('             Kloof');
  Writeln ('             3640');
  Writeln ('I hope to hear from you soon!');
  Writeln; Writeln;
  Write   ('Hit any key to exit ...');
  Readkey;
END.

/////////////////////////////////////////////////////////////////////////////
//                                                                         //
// TUTPROG5.CPP - VGA Trainer Program 5 (in Turbo C++ 3.0)                 //
//                                                                         //
// "The VGA Trainer Program" is written by Denthor of Asphyxia. However it //
// was limited to Pascal only in its first run.  All I have done is taken  //
// his original release, translated it to C++ and touched up a few things. //
// I take absolutely no credit for the concepts presented in this code and //
// am NOT the person to ask for help if you are having trouble.            //
//                                                                         //
// Program Notes : This program presents the basic demo scroller.          //
//                                                                         //
//                 If you are compiling this code command line, be sure to //
//                 use the "-ml" parameter (large memory model).           //
//                 Otherwise, the program will compile and link, but will  //
//                 lock up your system.                                    //
//                                                                         //
// Author        : Grant Smith (Denthor) - denthor@beastie.cs.und.ac.za    //
// Translator    : Christopher G. Mann   - r3cgm@dax.cc.uakron.edu         //
//                                                                         //
// Last Modified : December 27, 1994                                       //
//                                                                         //
/////////////////////////////////////////////////////////////////////////////
 
//               //
// INCLUDE FILES //
//               //
 
  #include <conio.h>
			   // clrscr(), getch(), kbhit()
  #include <dos.h>
			   // MK_FP, geninterrupt()
  #include <iostream.h>
			   // cout
  #include <stdio.h>
			   // fopen(), fread(), fclose(), FILE
  #include <stdlib.h>
			   // calloc(), free(), exit()
 
//           //
// CONSTANTS //
//           //
 
  const XSize = 16;        // the width  of our font
  const YSize = 16;        // the height of our font
  const NumLetters = 62;   // the number of characters in our font
 
//                     //
// FUNCTION PROTOTYPES //
//                     //
 
  // MODE SETTING FUNCTIONS
  void SetMCGA();
  void SetText();
 
  // UTILITY FUNCTIONS
  void Pal(unsigned char ColorNo, unsigned char R,
	   unsigned char G,       unsigned char B);
  void LoadPal(char *FileName);
  void Putpixel(int x, int y, unsigned char Col, unsigned char *Where);
  void WaitRetrace();
  int  Exist(char *FileName);
 
  // MID-LEVEL FUNCTIONS
  void Setup();
  void ScrollMsg (char *Msg, int SizeMsg);
 
//                 //
// GLOBAL TYPEDEFs //
//                 //
 
  typedef unsigned char Letter[XSize][YSize];
 
//                              //
// GLOBAL VARIABLE DECLARATIONS //
//                              //
 
  // pointer to the offset of the VGA memory
  unsigned char *vga = (unsigned char *) MK_FP(0xA000, 0);
 
  // pointer to our index of font data
  Letter *Font;
 
 
///////////////////////////////////////////////////////////////////////////////
//                                                                           //
//                                MAIN FUNCTION                              //
//                                                                           //
///////////////////////////////////////////////////////////////////////////////
 
void main() {
 
  clrscr();
  cout
    << "This program will give you an example of a scrolly. If the file\n"
    << "SOFTROCK.FNT is in the current directory, this program will scroll\n"
    << "letters, otherwise it will only scroll bars. It also searches for\n"
    << "PALLETTE.COL, which it uses for it''s pallette. Both SOFTROCK.FNT\n"
    << "and PALLETTE.COL come with TEXTER5.ZIP, at a BBS near you.\n\n";
  cout
    << "You will note that you can change what the scrolly says merely by\n"
    << "changing the string in the program.\n\n";
 
  Setup();
 
  do ScrollMsg ("ASPHYXIA RULZ!!!   ",19); while (!kbhit());
  getch();
 
  SetText();
  free(Font);
 
  cout
    << "All done. This concludes the fifth sample program in the ASPHYXIA\n"
    << "Training series. You may reach DENTHOR under the name of GRANT\n"
    << "SMITH on the MailBox BBS, or leave a message to ASPHYXIA on the\n"
    << "ASPHYXIA BBS. Get the numbers from Roblist, or write to :\n"
    << "             Grant Smith\n"
    << "             P.O. Box 270\n"
    << "             Kloof\n"
    << "             3640\n"
    << "I hope to hear from you soon!\n\n";
  cout
    << "Hit any key to exit ...";
  getch();
 
}
 
 
/////////////////////////////////////////////////////////////////////////////
//                                                                         //
// SetMCGA() - This function gets you into 320x200x256 mode.               //
//                                                                         //
/////////////////////////////////////////////////////////////////////////////
 
void SetMCGA() {
  _AX = 0x0013;
  geninterrupt (0x10);
}
 
 
/////////////////////////////////////////////////////////////////////////////
//                                                                         //
// SetText() - This function gets you into text mode.                      //
//                                                                         //
/////////////////////////////////////////////////////////////////////////////
 
void SetText() {
  _AX = 0x0003;
  geninterrupt (0x10);
}
 
 
/////////////////////////////////////////////////////////////////////////////
//                                                                         //
// Pal() - This sets the Red, Green, and Blue values of a certain color.   //
//                                                                         //
/////////////////////////////////////////////////////////////////////////////
 
void Pal(unsigned char ColorNo, unsigned char R,
	 unsigned char G,       unsigned char B) {
 
  outp (0x03C8,ColorNo); // here is the pallette color I want to set
  outp (0x03C9,R);
  outp (0x03C9,G);
  outp (0x03C9,B);
 
}
 
 
/////////////////////////////////////////////////////////////////////////////
//                                                                         //
// LoadPal() - This loads the Pallette file and puts it on screen.         //
//                                                                         //
/////////////////////////////////////////////////////////////////////////////
 
void LoadPal(char *FileName) {
 
  typedef unsigned char DACType[256][3]; // [256] colors, [3] types (R,G,B)
  DACType DAC;
  FILE *fp;
  int loop1;
 
  fp = fopen(FileName,"rb");
  fread(DAC,sizeof(DACType),1,fp);
  fclose(fp);
 
  for (loop1=0; loop1<256; loop1++)
    Pal(loop1, DAC[loop1][0], DAC[loop1][1], DAC[loop1][2]);
 
}
 
 
/////////////////////////////////////////////////////////////////////////////
//                                                                         //
// Putpixel() - This puts a pixel at X,Y using color Col, on VGA or the    //
//              Virtual Screen;                                            //
//                                                                         //
/////////////////////////////////////////////////////////////////////////////
 
void Putpixel (int x, int y, unsigned char Col, unsigned char *Where) {
  memset(Where+(x+(y*320)),Col,1);
}
 
 
/////////////////////////////////////////////////////////////////////////////
//                                                                         //
// WaitRetrace() - This waits until you are in a Verticle Retrace.         //
//                                                                         //
/////////////////////////////////////////////////////////////////////////////
 
void WaitRetrace() {
 
  _DX = 0x03DA;
 
  l1: asm {
	in  al,dx;
	and al,0x08;
	jnz l1;
      }
 
  l2: asm {
	in  al,dx;
	and al,0x08;
	jz  l2;
      }
}
 
 
/////////////////////////////////////////////////////////////////////////////
//                                                                         //
// Exist() - Checks to see if file exists or not.                          //
//                                                                         //
/////////////////////////////////////////////////////////////////////////////
 
int Exist (char *FileName) {
 
  FILE *fp;
 
  if ((fp = fopen(FileName,"rb")) != NULL) {
    fclose(fp);
    return 1;
  }
  else
    return 0;
 
}
 
 
/////////////////////////////////////////////////////////////////////////////
//                                                                         //
// Setup() - This loads the font and the pallette.                         //
//                                                                         //
/////////////////////////////////////////////////////////////////////////////
 
void Setup() {
 
  FILE *fp;
  int loop1, loop2, loop3;
 
  Font = (Letter *) calloc(NumLetters,sizeof(Letter));
 
    if (Font == NULL) { // always check to make sure you have enough memory!
      SetText();
      cout << "Not enough memory available, exiting program...";
      exit(1);
    }
 
  if (Exist("SOFTROCK.FNT\0")) { // don't forget the "\0" null terminator
    fp = fopen("SOFTROCK.FNT","rb");
    fread(Font,sizeof(Letter),NumLetters,fp);
    cout << "SoftRock.FNT from TEXTER5 found in current directory. Using.\n";
    fclose(fp);
  }
  else {
    cout << "SoftRock.FNT from TEXTER5 not found in current directory.\n";
    for     (loop1=0; loop1<NumLetters; loop1++)
      for   (loop2=0; loop2<XSize;      loop2++)
	for (loop3=0; loop3<YSize;      loop3++)
	  Font[loop1][loop2][loop3] = loop2;
  }
 
  if (Exist("PALLETTE.COL\0")) // don't forget the \0 null terminator
    cout << "Pallette.COL from TEXTER5 found in current directory. Using.\n";
  else
    cout << "Pallette.COL from TEXTER5 not found in current directory.\n";
 
  cout << "\n\nHit any key to continue ...";
  getch();
 
  SetMCGA();
 
  if (Exist("PALLETTE.COL\0")) LoadPal("PALLETTE.COL\0");
}
 
 
/////////////////////////////////////////////////////////////////////////////
//                                                                         //
// ScrollMsg() - This scrolls the string in Msg across the screen.         //
//                                                                         //
/////////////////////////////////////////////////////////////////////////////
 
void ScrollMsg (char *Msg, int SizeMsg) {
 
  int loop1, loop2, loop3;
  int Location = 100; // specify how far from the top of the screen we want
		      // the scroller to appear
 
  // MAIN LOOP - do every letter in Msg
  for (loop1 = 0; loop1 < SizeMsg; loop1++) {
 
    // Do this loop <n> number of times where <n> = the width of a letter
    for (loop2 = 0; loop2 < XSize; loop2++) {
 
    // There are two loops here.
    //
    // 1. Copy YSize rows to the left by 1.  In effect, this frees up a
    //    blank column of vertical pixels on the right side of the screen.
    // 2. Replace that new blank column with pixels from our Font[] table.
 
    WaitRetrace();
 
    for (loop3=Location; loop3<Location+YSize; loop3++)
      // move each row to the left by 1
      memcpy(vga+(0+(loop3*320)), vga+(1+(loop3*320)), 320);
 
    for (loop3=Location; loop3<Location+YSize; loop3++)
      // Replace the new column on the right with information from Font[].
      // In the following statement:
      //   (320,         - y location (the rightmost column)
      //   loop3,        - x location (the current row we are working with)
      //   Font[...      - Get information from our Font table.  All of this
      //                   complex indexing really just gives us the pallette
      //                   number we are putting to the screen at a given
      //                   location.
      //    [(Msg[loop1]-32)] - Access the correct letter from our Font
      //                        table.  The (Msg[loop1]) would give us the
      //                        ASCII value of the letter we want to display,
      //                        but we need to subtract 32 to coordinate the
      //                        ASCII value with our Font table.
      //    [loop2]           - the column index of the letter we are using
      //    [loop3-Location]  - the row    index of the letter we are using
      Putpixel (319,loop3,Font[(Msg[loop1]-32)][loop2][loop3-Location],vga);
 
    } // we have now inserted a new letter on the right side of the screen
 
  // This next bit scrolls by one pixel after each letter so that there
  // are gaps between the letters
 
  WaitRetrace();
 
  for (loop3=Location; loop3<Location+YSize; loop3++)
    // move each row to the left by 1 (same as above)
    memcpy( vga+(loop3*320), vga+(1+(loop3*320)), 320);
 
  for (loop3 = 100; loop3 < 100 + YSize; loop3++)
    // put a blank column of pixels
    Putpixel(319,loop3,0,vga);
 
  } // we have now scrolled the entire message once
 
}