here is my 'correct' version of fisheye variation

2.10/Source/VarEyefish.pas

@@ -0,0 +1,51 @@
+unit VarEyefish;
+
+interface
+
+uses
+  BaseVariation, XFormMan;
+
+type
+  TVariationEyefish = class(TBaseVariation)
+  public
+    class function GetName: string; override;
+    class function GetInstance: TBaseVariation; override;
+
+    procedure CalcFunction; override;
+  end;
+
+implementation
+
+uses
+  math;
+
+// TVariationEyefish
+
+///////////////////////////////////////////////////////////////////////////////
+procedure TVariationEyefish.CalcFunction;
+var
+  Flength, r: double;
+begin
+  Flength := sqrt(FTx^ * FTx^ + FTy^ * FTy^);
+
+  r := 2 * Flength / (Flength + 1);
+  FPx^ := FPx^ + vvar * r * FTx^ / Flength;
+  FPy^ := FPy^ + vvar * r * FTy^ / Flength;
+end;
+
+///////////////////////////////////////////////////////////////////////////////
+class function TVariationEyefish.GetInstance: TBaseVariation;
+begin
+  Result := TVariationEyefish.Create;
+end;
+
+///////////////////////////////////////////////////////////////////////////////
+class function TVariationEyefish.GetName: string;
+begin
+  Result := 'eyefish';
+end;
+
+///////////////////////////////////////////////////////////////////////////////
+initialization
+  RegisterVariation(TVariationEyefish);
+end.