55c07bf41d
git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@48 8e941d3f-bd1b-0410-a28a-d453659cc2b4
57 lines
1.0 KiB
ObjectPascal
57 lines
1.0 KiB
ObjectPascal
unit noise;
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{$ifdef fpc}
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{$mode delphi}
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{$endif}
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interface
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uses
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Classes, SysUtils;
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function IntNoise(x: Integer): Double;
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function Linear_Interpolate(a, b, x: Double): Double;
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function Cosine_Interpolate(a, b, x: Double): Double;
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function Cubic_Interpolate(v0, v1, v2, v3, x: Double): Double;
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implementation
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function IntNoise(x: Integer): Double;
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var
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xl: Integer;
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begin
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xl := (x shl 13) xor x;
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Result := (xl * (xl * xl * 15731 + 789221) + 1376312589) and $7fffffff;
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Result := 1.0 - (Result / 1073741824.0);
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end;
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function Linear_Interpolate(a, b, x: Double): Double;
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begin
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Result := a * (1-x) + b * x;
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end;
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function Cosine_Interpolate(a, b, x: Double): Double;
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var
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f, ft: Double;
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begin
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ft := x * Pi;
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f := (1.0 - cos(ft)) * 0.5;
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Result := a * (1 - f) + b * f;
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end;
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function Cubic_Interpolate(v0, v1, v2, v3, x: Double): Double;
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var
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P, Q, R, S: Double;
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begin
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P := (v3 - v2) - (v0 - v1);
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Q := (v0 - v1) - P;
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R := v2 - v0;
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S := v1;
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Result := P * x * x * x + Q * x * x + R * x + S;
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end;
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end.
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