1 // Copyright (C) 2006 Mathias Froehlich - Mathias.Froehlich@web.de
3 // This library is free software; you can redistribute it and/or
4 // modify it under the terms of the GNU Library General Public
5 // License as published by the Free Software Foundation; either
6 // version 2 of the License, or (at your option) any later version.
8 // This library is distributed in the hope that it will be useful,
9 // but WITHOUT ANY WARRANTY; without even the implied warranty of
10 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 // Library General Public License for more details.
13 // You should have received a copy of the GNU General Public License
14 // along with this program; if not, write to the Free Software
15 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
24 static T pi() { return T(3.1415926535897932384626433832795029L); }
25 static T twopi() { return 2*T(3.1415926535897932384626433832795029L); }
27 static T min(const T& a, const T& b)
28 { return a < b ? a : b; }
29 static T min(const T& a, const T& b, const T& c)
30 { return min(min(a, b), c); }
31 static T min(const T& a, const T& b, const T& c, const T& d)
32 { return min(min(min(a, b), c), d); }
33 static T max(const T& a, const T& b)
34 { return a > b ? a : b; }
35 static T max(const T& a, const T& b, const T& c)
36 { return max(max(a, b), c); }
37 static T max(const T& a, const T& b, const T& c, const T& d)
38 { return max(max(max(a, b), c), d); }
40 // clip the value of a to be in the range between and including _min and _max
41 static T clip(const T& a, const T& _min, const T& _max)
42 { return max(_min, min(_max, a)); }
45 * Seek a variable towards a target value with given rate and timestep
47 * @param var Variable or eg. SGPropObj
48 * @param target Target value
49 * @param rate Max. change rate/sec
50 * @param dt Time step (sec)
53 static T seek(Var& var, T target, T rate, T dt)
56 return var = min(var + rate * dt, target);
58 return var = max(var - rate * dt, target);
61 static int sign(const T& a)
63 if (a < -SGLimits<T>::min())
65 else if (SGLimits<T>::min() < a)
71 static T rad2deg(const T& val)
72 { return val*180/pi(); }
73 static T deg2rad(const T& val)
74 { return val*pi()/180; }
76 // normalize the value to be in a range between [min, max[
78 normalizePeriodic(const T& min, const T& max, const T& value)
81 if (range < SGLimits<T>::min())
83 T normalized = value - range*floor((value - min)/range);
84 // two security checks that can only happen due to roundoff
85 if (normalized <= min)
87 if (max <= normalized)
92 // normalize the angle to be in a range between [-pi, pi[
94 normalizeAngle(const T& angle)
95 { return normalizePeriodic(-pi(), pi(), angle); }
97 // normalize the angle to be in a range between [0, 2pi[
99 normalizeAngle2(const T& angle)
100 { return normalizePeriodic(0, twopi(), angle); }
102 static T round(const T& v)
103 { return floor(v + T(0.5)); }
104 static int roundToInt(const T& v)
105 { return int(round(v)); }
107 // Linear interpolation between two arbitrary typed values
109 static S lerp(const S& val0, const S& val1, const T& t)
110 { return val0*(T(1) - t) + val1*t; }
112 /// Returns true if v is a NaN value
113 /// Use with care: allways code that you do not need to use that!
114 static bool isNaN(const T& v)
118 #elif defined HAVE_STD_ISNAN
119 return std::isnan(v);
121 // Use that every compare involving a NaN returns false
122 // But be careful, some usual compiler switches like for example
123 // -fast-math from gcc might optimize that expression to v != v which
124 // behaves exactly like the opposite ...