Games of Daze/Infomagic - Games of Daze (Summer 1995) (Disc 1 of 2).iso/x2ftp/msdos/docs/tut6new/tut6.pas

Pascal/Delphi Source File | 1995-01-04 | 9KB | 259 lines

(*****************************************************************************)
(*                                                                           *)
(* TUT6.PAS - VGA Trainer Program 6 (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 pregenerated arrays.                *)
(*                                                                           *)
(* Author        : Grant Smith (Denthor)  - [e-mail]     *)
(*                                                                           *)
(*****************************************************************************)

{$X+}
USES crt;

CONST VGA = $a000;

TYPE tbl = Array [1..8000] of real;
             { This will be the shape of the 'table' where we look up
               values, which is faster then calculating them }

VAR loop1:integer;
    Pall : Array [1..20,1..3] of byte;
      { This is our temporary pallette. We ony use colors 1 to 20, so we
        only have variables for those ones. }

{──────────────────────────────────────────────────────────────────────────}
Procedure SetMCGA;  { This procedure gets you into 320x200x256 mode. }
BEGIN
  asm
     mov        ax,0013h
     int        10h
  end;
END;


{──────────────────────────────────────────────────────────────────────────}
Procedure SetText;  { This procedure returns you to text mode.  }
BEGIN
  asm
     mov        ax,0003h
     int        10h
  end;
END;

{──────────────────────────────────────────────────────────────────────────}
Procedure Cls (Col : Byte);
   { This clears the screen to the specified color }
BEGIN
  Fillchar (Mem [VGA:0],64000,col);
END;


{──────────────────────────────────────────────────────────────────────────}
Procedure Putpixel (X,Y : Integer; Col : Byte);
  { This puts a pixel on the screen by writing directly to memory. }
BEGIN
  Mem [VGA:X+(Y*320)]:=Col;
END;


{──────────────────────────────────────────────────────────────────────────}
procedure WaitRetrace; assembler;
  {  This waits for a vertical retrace to reduce snow on the screen }
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;


{──────────────────────────────────────────────────────────────────────────}
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;


{──────────────────────────────────────────────────────────────────────────}
Function rad (theta : real) : real;
  {  This calculates the degrees of an angle }
BEGIN
  rad := theta * pi / 180
END;



{──────────────────────────────────────────────────────────────────────────}
Procedure NormCirc;
  { This generates a spireal without using a lookup table }
VAR deg,radius:real;
    x,y:integer;

BEGIN
  gotoxy (1,1);
  Writeln ('Without pregenerated arrays.');
  for loop1:=60 downto 43 do BEGIN
    deg:=0;
    radius:=loop1;
    repeat
      X:=round(radius*COS (rad (deg)));
      Y:=round(radius*sin (rad (deg)));
      putpixel (x+160,y+100,61-loop1);
      deg:=deg+0.4;           { Increase the degree so the circle is round }
      radius:=radius-0.02;    { Decrease the radius for a spiral effect }
    until radius<0; {  Continue till at the centre (the radius is zero) }
  END;
END;


{──────────────────────────────────────────────────────────────────────────}
Procedure LookupCirc;
  {  This draws a spiral using a lookup table }
VAR radius:real;
    x,y,pos:integer;
    costbl : ^tbl;
    sintbl : ^tbl;

    Procedure Setupvars;
      {  This is a nested procedure (a procedure in a procedure), and may
         therefore only be used from within the main part of this procedure.
         This section gets the memory for the table, then generates the
         table. }
    VAR deg:real;
    BEGIN
      getmem (costbl,sizeof(costbl^));
      getmem (sintbl,sizeof(sintbl^));
      deg:=0;
      for loop1:=1 to 8000 do BEGIN         { There are 360 degrees in a    }
        deg:=deg+0.4;                       { circle. If you increase the   }
        costbl^[loop1]:=cos (rad(deg));     { degrees by 0.4, the number of }
        sintbl^[loop1]:=sin (rad(deg));     { needed parts of the table is  }
      END;                                  { 360/0.4=8000                  }
    END;
    { NB : For greater accuracy I increase the degrees by 0.4, because if I
           increase them by one, holes are left in the final product as a
           result of the rounding error margin. This means the pregen array
           is bigger, takes up more memory and is slower to calculate, but
           the finished product looks better.}

BEGIN
  cls (0);
  gotoxy (1,1);
  Writeln ('Generating variables....');
  setupvars;
  gotoxy (1,1);
  Writeln ('With pregenerated arrays.');
  for loop1:=60 downto 43 do BEGIN
    pos:=1;
    radius:=loop1;
    repeat
      X:=round (radius*costbl^[pos]);   { Note how I am not recalculating sin}
      Y:=round (radius*sintbl^[pos]);   { and cos for each point.            }
      putpixel (x+160,y+100,61-loop1);
      radius:=radius-0.02;
      inc (pos);
      if pos>8000 then pos:=1;    { I only made a table from 1 to 8000, so it}
                                  { must never exceed that, or the program   }
                                  { will probably crash.                     }
    until radius<0;
  END;
  freemem (costbl,sizeof(costbl^));   { Freeing the memory taken up by the   }
  freemem (sintbl,sizeof(sintbl^));   { tables. This is very important.      }
END;


{──────────────────────────────────────────────────────────────────────────}
Procedure PalPlay;
  { This procedure mucks about with our "virtual pallette", then shoves it
    to screen. }
Var Tmp : Array[1..3] of Byte;
  { This is used as a "temporary color" in our pallette }
    loop1 : Integer;
BEGIN
   Move(Pall[1],Tmp,3);
     { This copies color 1 from our virtual pallette to the Tmp variable }
   Move(Pall[2],Pall[1],18*3);
     { This moves the entire virtual pallette down one color }
   Move(Tmp,Pall[18],3);
     { This copies the Tmp variable to no. 18 of the virtual pallette }
   WaitRetrace;
   For loop1:=1 to 18 do
     pal (loop1,pall[loop1,1],pall[loop1,2],pall[loop1,3]);
END;


BEGIN
  ClrScr;
  writeln ('Hi there! This program will demonstrate the usefullness of ');
  writeln ('pregenerated arrays, also known as lookup tables. The program');
  writeln ('will first draw a spiral without using a lookup table, rotate');
  writeln ('the pallette until a key is pressed, the calculate the lookup');
  writeln ('table, then draw the same spiral using the lookup table.');
  writeln;
  writeln ('This is merely one example for the wide range of uses of a ');
  writeln ('lookup table.');
  writeln;
  writeln;
  Write ('  Hit any key to contine ...');
  Readkey;
  setmcga;
  directvideo:=FALSE;  { This handy trick allows you to use GOTOXY and }
                       { Writeln in GFX mode. Hit CTRL-F1 on it for more }
                       { info/help }
  For Loop1 := 1 to 18 do BEGIN
    Pall[Loop1,1] := (Loop1*3)+9;
    Pall[Loop1,2] := 0;
    Pall[Loop1,3] := 0;
  END;
       { This sets colors 1 to 18 to values between 12 to 63. }

   WaitRetrace;
   For loop1:=1 to 18 do
     pal (loop1,pall[loop1,1],pall[loop1,2],pall[loop1,3]);
        { This sets the true pallette to variable Pall }

  normcirc;         { This draws a spiral without lookups }
  Repeat
    PalPlay;
  Until keypressed;
  readkey;
  lookupcirc;       { This draws a spiral with lookups }
  Repeat
    PalPlay;
  Until keypressed;
  Readkey;

  SetText;
  Writeln ('All done. This concludes the sixth 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. I am also an avid Connectix BBS user.');
  Writeln ('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.