138 lines
4.6 KiB
C++
138 lines
4.6 KiB
C++
/**
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* @file llcriticaldamp.cpp
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* @brief Implementation of the critical damping functionality.
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*
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* $LicenseInfo:firstyear=2002&license=viewergpl$
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*
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* Copyright (c) 2002-2009, Linden Research, Inc.
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*
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* Second Life Viewer Source Code
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* The source code in this file ("Source Code") is provided by Linden Lab
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* to you under the terms of the GNU General Public License, version 2.0
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* ("GPL"), unless you have obtained a separate licensing agreement
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* ("Other License"), formally executed by you and Linden Lab. Terms of
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* the GPL can be found in doc/GPL-license.txt in this distribution, or
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* online at http://secondlifegrid.net/programs/open_source/licensing/gplv2
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*
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* There are special exceptions to the terms and conditions of the GPL as
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* it is applied to this Source Code. View the full text of the exception
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* in the file doc/FLOSS-exception.txt in this software distribution, or
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* online at
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* http://secondlifegrid.net/programs/open_source/licensing/flossexception
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*
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* By copying, modifying or distributing this software, you acknowledge
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* that you have read and understood your obligations described above,
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* and agree to abide by those obligations.
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*
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* ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
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* WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
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* COMPLETENESS OR PERFORMANCE.
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* $/LicenseInfo$
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*/
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#include "linden_common.h"
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#include "llcriticaldamp.h"
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#include <algorithm>
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//-----------------------------------------------------------------------------
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// static members
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//-----------------------------------------------------------------------------
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LLFrameTimer LLSmoothInterpolation::sInternalTimer;
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std::vector<LLSmoothInterpolation::Interpolant> LLSmoothInterpolation::sInterpolants;
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F32 LLSmoothInterpolation::sTimeDelta;
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std::pair<F32, F32> sCachedEntry;
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// helper functors
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struct LLSmoothInterpolation::CompareTimeConstants
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{
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bool operator()(const F32& a, const LLSmoothInterpolation::Interpolant& b) const
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{
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return a < b.mTimeScale;
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}
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bool operator()(const LLSmoothInterpolation::Interpolant& a, const F32& b) const
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{
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return a.mTimeScale < b; // bottom of a is higher than bottom of b
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}
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bool operator()(const LLSmoothInterpolation::Interpolant& a, const LLSmoothInterpolation::Interpolant& b) const
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{
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return a.mTimeScale < b.mTimeScale; // bottom of a is higher than bottom of b
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}
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};
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//-----------------------------------------------------------------------------
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// LLSmoothInterpolation()
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//-----------------------------------------------------------------------------
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LLSmoothInterpolation::LLSmoothInterpolation()
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{
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sTimeDelta = 0.f;
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sCachedEntry = std::pair<F32, F32>(-1.f, -1.f);
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}
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// static
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//-----------------------------------------------------------------------------
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// updateInterpolants()
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//-----------------------------------------------------------------------------
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void LLSmoothInterpolation::updateInterpolants()
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{
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sTimeDelta = sInternalTimer.getElapsedTimeAndResetF32();
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for (size_t i = 0; i < sInterpolants.size(); i++)
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{
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Interpolant& interp = sInterpolants[i];
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interp.mInterpolant = calcInterpolant(interp.mTimeScale);
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if (sCachedEntry.first == interp.mTimeScale)
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{
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sCachedEntry.second = interp.mInterpolant;
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}
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}
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}
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//-----------------------------------------------------------------------------
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// getInterpolant()
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//-----------------------------------------------------------------------------
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F32 LLSmoothInterpolation::getInterpolant(F32SecondsImplicit time_constant, bool use_cache)
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{
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if (time_constant == 0.f)
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{
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return 1.f;
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}
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if (use_cache)
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{
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if (sCachedEntry.first == time_constant)
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{
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return sCachedEntry.second;
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}
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interpolant_vec_t::iterator find_it = std::lower_bound(sInterpolants.begin(), sInterpolants.end(), time_constant.value(), CompareTimeConstants());
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if (find_it != sInterpolants.end() && find_it->mTimeScale == time_constant)
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{
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sCachedEntry = std::make_pair(time_constant.value(), find_it->mInterpolant);
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return find_it->mInterpolant;
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}
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else
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{
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Interpolant interp;
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interp.mTimeScale = time_constant.value();
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interp.mInterpolant = calcInterpolant(time_constant.value());
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sInterpolants.insert(find_it, interp);
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sCachedEntry = std::make_pair(time_constant.value(), interp.mInterpolant);
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return interp.mInterpolant;
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}
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}
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else
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{
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return calcInterpolant(time_constant.value());
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}
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}
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//-----------------------------------------------------------------------------
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// calcInterpolant()
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//-----------------------------------------------------------------------------
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F32 LLSmoothInterpolation::calcInterpolant(F32 time_constant)
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{
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return llclamp(1.f - powf(2.f, -sTimeDelta / time_constant), 0.f, 1.f);
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}
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