/** * @file llcriticaldamp.cpp * @brief Implementation of the critical damping functionality. * * $LicenseInfo:firstyear=2002&license=viewerlgpl$ * Second Life Viewer Source Code * 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 * $/LicenseInfo$ */ #include "linden_common.h" #include "llcriticaldamp.h" #include <algorithm> //----------------------------------------------------------------------------- // static members //----------------------------------------------------------------------------- LLFrameTimer LLSmoothInterpolation::sInternalTimer; std::vector<LLSmoothInterpolation::Interpolant> LLSmoothInterpolation::sInterpolants; F32 LLSmoothInterpolation::sTimeDelta; // helper functors struct LLSmoothInterpolation::CompareTimeConstants { bool operator()(const F32& a, const LLSmoothInterpolation::Interpolant& b) const { return a < b.mTimeScale; } bool operator()(const LLSmoothInterpolation::Interpolant& a, const F32& b) const { return a.mTimeScale < b; // bottom of a is higher than bottom of b } bool operator()(const LLSmoothInterpolation::Interpolant& a, const LLSmoothInterpolation::Interpolant& b) const { return a.mTimeScale < b.mTimeScale; // bottom of a is higher than bottom of b } }; //----------------------------------------------------------------------------- // LLSmoothInterpolation() //----------------------------------------------------------------------------- LLSmoothInterpolation::LLSmoothInterpolation() { sTimeDelta = 0.f; } // static //----------------------------------------------------------------------------- // updateInterpolants() //----------------------------------------------------------------------------- void LLSmoothInterpolation::updateInterpolants() { sTimeDelta = sInternalTimer.getElapsedTimeAndResetF32(); for (S32 i = 0; i < sInterpolants.size(); i++) { Interpolant& interp = sInterpolants[i]; interp.mInterpolant = calcInterpolant(interp.mTimeScale); } } //----------------------------------------------------------------------------- // getInterpolant() //----------------------------------------------------------------------------- F32 LLSmoothInterpolation::getInterpolant(F32SecondsImplicit time_constant, bool use_cache) { if (time_constant == 0.f) { return 1.f; } if (use_cache) { interpolant_vec_t::iterator find_it = std::lower_bound(sInterpolants.begin(), sInterpolants.end(), time_constant.value(), CompareTimeConstants()); if (find_it != sInterpolants.end() && find_it->mTimeScale == time_constant) { return find_it->mInterpolant; } else { Interpolant interp; interp.mTimeScale = time_constant.value(); interp.mInterpolant = calcInterpolant(time_constant.value()); sInterpolants.insert(find_it, interp); return interp.mInterpolant; } } else { return calcInterpolant(time_constant.value()); } } //----------------------------------------------------------------------------- // calcInterpolant() //----------------------------------------------------------------------------- F32 LLSmoothInterpolation::calcInterpolant(F32 time_constant) { return llclamp(1.f - powf(2.f, -sTimeDelta / time_constant), 0.f, 1.f); }