More Noise Sphere Noise (simple source code)

[wlkngowl@unix.asb.com]

Ok, no language holy wars.  This was quickie to test out
the Noise Sphere plotting.  It's in Pascal, but it's
understandable.

{ Simple demo of a Noise Sphere in Turbo Pascal         }
{ (If only I had a really awful RNG to test it with...) }

program NoiseSphere;
  uses Graph, Crt;

const
  BGIPath = ''; { where those silly Borland *.BGI drivers are }

var
  GraphMode,
  GraphDriver: Integer;


type
  Polar = record
    r, theta, phi: Real;
  end;

  Cartesian = record
    x,y,z: Real;
  end;

procedure PolarToCartesian(var P: Polar; var C: Cartesian);
begin
  C.x := P.r * Sin(P.phi) * Cos(P.theta);
  C.y := P.r * Sin(P.phi) * Sin(P.theta);
  C.z := P.r * Cos(P.phi);
end;

procedure Plot(var C: Cartesian);
begin
  with C do begin
    PutPixel(100+(Round(100*y)), 200-(Round(120*z)), Yellow);
    PutPixel(320+(Round(100*x)), 200-(Round(120*y)), Red);
    PutPixel(540+(Round(100*x)), 200-(Round(120*z)), Blue);
  end;
  Delay(1);
end;


function ByteToReal(b: Byte): Real;
begin
  ByteToReal := b / 256;
end;

function InitScreen: Integer;
begin
  GraphMode := VGAHi;
  GraphDriver := EGA;
  InitGraph(GraphDriver,GraphMode,BGIPath);
  InitScreen := GraphResult;
end;

var
  n: LongInt;
  X: Array [ 0..2 ] of Real;
  P: Polar;
  C: Cartesian;
begin
  InitScreen;
  Randomize;
  for n := 0 to 2 do X[n] :=
{$ifdef USEDEV}
{$else}
    ByteToReal(Random(256));
{$endif}
  n := 0;
  repeat
    with P do begin
      r := Sqrt(X[(n+2) mod 3]);
      theta := pi * X[(n+1) mod 3];
      phi := 2 * pi * X[n];
    end;
    PolarToCartesian(P,C);
    Plot(C);
    X[n] :=
{$ifdef USEDEV}
{$else}
    ByteToReal(Random(256));
{$endif}
    n := (n + 1) mod 3;
  until KeyPressed;
    ReadKey;
  RestoreCrtMode;
end.