source: trunk/PerlinNoise.pas

unit PerlinNoise;

interface

uses
  Classes, SysUtils;

function IntNoise(X: Integer): Double;

function LinearInterpolate(A, B, X: Double): Double;
function CosineInterpolate(A, B, X: Double): Double;
function CubicInterpolate(V0, V1, V2, V3, X: Double): Double;


implementation

function IntNoise(X: Integer): Double;
var
  Xl: Integer;
begin
  Xl := (X shl 13) xor X;
  Result := (Xl * (Xl * Xl * 15731 + 789221) + 1376312589) and $7fffffff;
  Result := 1.0 - (Result / 1073741824.0);
end;

function LinearInterpolate(A, B, X: Double): Double;
begin
  Result := A * (1 - X) + B * X;
end;

function CosineInterpolate(A, B, X: Double): Double;
var
  F, Ft: Double;
begin
  Ft := X * Pi;
  F := (1.0 - Cos(Ft)) * 0.5;
  Result := A * (1 - F) + B * F;
end;

function CubicInterpolate(V0, V1, V2, V3, X: Double): Double;
var
  P, Q, R, S: Double;
begin
  P := (V3 - V2) - (V0 - V1);
  Q := (V0 - V1) - P;
  R := V2 - V0;
  S := V1;

  Result := P * X * X * X + Q * X * X + R * X + S;
end;

end.