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//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
// * Neither the name of NVIDIA CORPORATION nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``AS IS'' AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
// OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Copyright (c) 2018 NVIDIA Corporation. All rights reserved.
#include "Apex.h"
#include "variable_oscillator.h"
#include "PxMath.h"
namespace nvidia
{
namespace apex
{
variableOscillator::variableOscillator(float min, float max, float initial, float period) :
mMin(min),
mMax(max),
mPeriod(period),
mStartVal(initial),
mLastVal(initial)
{
mCumTime = 0.0f;
mGoingUp = true;
mEndVal = computeEndVal(mMin, mMax);
}
variableOscillator::~variableOscillator()
{
}
float variableOscillator::computeEndVal(float current, float maxOrMin)
{
float target;
float maxDelta;
float quarterVal;
// compute the max range of the oscillator
maxDelta = maxOrMin - current;
// find the 'lower bound' of the oscillator peak
quarterVal = current + (maxDelta / 4.0f);
// get a rand between 0 and 1
target = (float) ::rand() / (float) RAND_MAX;
// scale the rand to the range we want
target = target * PxAbs(quarterVal - maxOrMin);
// add the offset to the scaled random number.
if (current < maxOrMin)
{
target = target + quarterVal;
}
else
{
target = quarterVal - target;
}
return(target);
}
float variableOscillator::updateVariableOscillator(float deltaTime)
{
float returnVal;
float halfRange;
mCumTime += deltaTime;
// has the function crossed a max or a min?
if ((mGoingUp && (mCumTime > (mPeriod / 2.0f))) ||
(!mGoingUp && (mCumTime > mPeriod)))
{
mStartVal = mLastVal;
if (mGoingUp)
{
mEndVal = computeEndVal(mStartVal, mMin);
}
else
{
mEndVal = computeEndVal(mStartVal, mMax);
mCumTime = mCumTime - mPeriod;
}
mGoingUp = !mGoingUp;
}
halfRange = 0.5f * PxAbs(mEndVal - mStartVal);
returnVal = -halfRange * PxCos(mCumTime * PxTwoPi / mPeriod) + halfRange + PxMin(mStartVal, mEndVal);
mLastVal = returnVal;
return(returnVal);
}
}
} // namespace nvidia::apex
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