/**
 * @file llcriticaldamp.cpp
 * @brief Implementation of the critical damping functionality.
 *
 * $LicenseInfo:firstyear=2002&license=viewergpl$
 *
 * Copyright (c) 2002-2009, Linden Research, Inc.
 *
 * Second Life Viewer Source Code
 * The source code in this file ("Source Code") is provided by Linden Lab
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 *
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 */

#include "linden_common.h"

#include "llcriticaldamp.h"

// Static members
LLFrameTimer LLCriticalDamp::sInternalTimer;
std::map<F32, F32> LLCriticalDamp::sInterpolants;
F32 LLCriticalDamp::sTimeDelta = 0.f;

//static
void LLCriticalDamp::updateInterpolants()
{
	sTimeDelta = sInternalTimer.getElapsedTimeAndResetF32();

	for (std::map<F32, F32>::iterator it = sInterpolants.begin(),
									  end = sInterpolants.end();
		 it != end; ++it)
	{
		it->second = llclamp(1.f - powf(2.f, -sTimeDelta / it->first),
							 0.f, 1.f);
	}
}

//static
F32 LLCriticalDamp::getInterpolant(F32 time_constant, bool use_cache)
{
	if (time_constant == 0.f)
	{
		return 1.f;
	}

	if (use_cache)
	{
		std::map<F32, F32>::iterator it = sInterpolants.find(time_constant);
		if (it != sInterpolants.end())
		{
			return it->second;
		}
	}

	F32 interpolant = llclamp(1.f - powf(2.f, -sTimeDelta / time_constant),
							  0.f, 1.f);
	if (use_cache)
	{
		sInterpolants[time_constant] = interpolant;
	}

	return interpolant;
}