1 /*! ========================================================================
2 ** Extended Template and Library
3 ** Utility Curve Template Class Implementations
4 ** $Id$
5 **
6 ** Copyright (c) 2002 Robert B. Quattlebaum Jr.
7 **
8 ** This package is free software; you can redistribute it and/or
9 ** modify it under the terms of the GNU General Public License as
10 ** published by the Free Software Foundation; either version 2 of
11 ** the License, or (at your option) any later version.
12 **
13 ** This package is distributed in the hope that it will be useful,
14 ** but WITHOUT ANY WARRANTY; without even the implied warranty of
15 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16 ** General Public License for more details.
17 **
18 ** === N O T E S ===========================================================
19 **
20 ** This is an internal header file, included by other ETL headers.
21 ** You should not attempt to use it directly.
22 **
23 ** ========================================================================= */
24 
25 /* === S T A R T =========================================================== */
26 
27 #ifndef __ETL__CURVE_FUNC_H
28 #define __ETL__CURVE_FUNC_H
29 
30 /* === H E A D E R S ======================================================= */
31 
32 #include <functional>
33 #include "_fixed.h"
34 
35 /* -- C L A S S E S --------------------------------------------------------- */
36 
37 template <class T, class K=float>
38 struct affine_combo
39 {
40 	// from (a) to (x) : x = a(1-t) + b(t)
operatoraffine_combo41 	T operator()(const T &a,const T &b,const K &t)const
42 	{
43 		return T( (b-a)*t+a );
44 	}
45 
46 	// from (x) to (a) : a = (x-b(t)) / (1-t)
reverseaffine_combo47 	T reverse(const T &x, const T &b, const K &t)const
48 	{
49 		return T( (x-t*b)*(static_cast<K>(1)/(static_cast<K>(1)-t)) );
50 	}
51 };
52 
53 template <class T, class K=float>
54 struct distance_func : public std::binary_function<T, T, K>
55 {
operatordistance_func56 	K operator()(const T &a,const T &b)const
57 	{
58 		T delta=b-a;
59 		return static_cast<K>(delta*delta);
60 	}
61 
cookdistance_func62 	K cook(const K &x)const { return x*x; }
uncookdistance_func63 	K uncook(const K &x)const { return sqrt(x); }
64 
65 };
66 
67 /* -- E N D ----------------------------------------------------------------- */
68 
69 #endif
70