Newer
Older
/**
* @file llcriticaldamp.cpp
* @brief Implementation of the critical damping functionality.
*
* $LicenseInfo:firstyear=2002&license=viewerlgpl$
* Copyright (C) 2010, Linden Research, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License only.
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
*/
#include "linden_common.h"
#include "llcriticaldamp.h"
//-----------------------------------------------------------------------------
// static members
//-----------------------------------------------------------------------------
LLFrameTimer LLCriticalDamp::sInternalTimer;
std::map<F32, F32> LLCriticalDamp::sInterpolants;
F32 LLCriticalDamp::sTimeDelta;
//-----------------------------------------------------------------------------
// LLCriticalDamp()
//-----------------------------------------------------------------------------
LLCriticalDamp::LLCriticalDamp()
{
sTimeDelta = 0.f;
}
// static
//-----------------------------------------------------------------------------
// updateInterpolants()
//-----------------------------------------------------------------------------
void LLCriticalDamp::updateInterpolants()
{
sTimeDelta = sInternalTimer.getElapsedTimeAndResetF32();
F32 time_constant;
for (std::map<F32, F32>::iterator iter = sInterpolants.begin();
iter != sInterpolants.end(); iter++)
{
time_constant = iter->first;
F32 new_interpolant = 1.f - pow(2.f, -sTimeDelta / time_constant);
new_interpolant = llclamp(new_interpolant, 0.f, 1.f);
sInterpolants[time_constant] = new_interpolant;
}
}
//-----------------------------------------------------------------------------
// getInterpolant()
//-----------------------------------------------------------------------------
F32 LLCriticalDamp::getInterpolant(const F32 time_constant, BOOL use_cache)
{
if (time_constant == 0.f)
{
return 1.f;
}
if (use_cache && sInterpolants.count(time_constant))
{
return sInterpolants[time_constant];
}
F32 interpolant = 1.f - pow(2.f, -sTimeDelta / time_constant);
interpolant = llclamp(interpolant, 0.f, 1.f);
if (use_cache)
{
sInterpolants[time_constant] = interpolant;
}
return interpolant;
}