khanat-code-old/code/nel/src/sound/driver/source.cpp

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2010-05-06 00:08:41 +00:00
// NeL - MMORPG Framework <http://dev.ryzom.com/projects/nel/>
// Copyright (C) 2010 Winch Gate Property Limited
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// This program 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 Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
#include "source.h"
#include "nel/misc/common.h"
using namespace NLMISC;
namespace NLSOUND
{
// common method used only with OptionManualRolloff. return the volume in 1/100th DB ( = mB) modified
sint32 ISource::computeManualRollOff(sint32 volumeMB, sint32 mbMin, sint32 mbMax, double alpha, float sqrdist, float distMin, float distMax)
{
if (sqrdist < distMin * distMin)
{
// no attenuation
return volumeMB;
}
else if (sqrdist > distMax * distMax)
{
// full attenuation
return mbMin;
}
else
{
double dist = (double) sqrt(sqrdist);
// linearly descending volume on a dB scale
double db1 = mbMin * (dist - distMin) / (distMax - distMin);
if (alpha == 0.0) {
volumeMB += (sint32) db1;
} else if (alpha > 0.0) {
double amp2 = 0.0001 + 0.9999 * (distMax - dist) / (distMax - distMin); // linear amp between 0.00001 and 1.0
double db2 = 2000.0 * log10(amp2); // convert to 1/100th decibels
volumeMB += (sint32) ((1.0 - alpha) * db1 + alpha * db2);
} else if (alpha < 0.0) {
double amp3 = distMin / dist; // linear amplitude is 1/distance
double db3 = 2000.0 * log10(amp3); // convert to 1/100th decibels
volumeMB += (sint32) ((1.0 + alpha) * db1 - alpha * db3);
}
clamp(volumeMB, mbMin, mbMax);
return volumeMB;
}
}
// common method used only with OptionManualRolloff. return the rolloff in amplitude ratio (gain)
float ISource::computeManualRolloff(double alpha, float sqrdist, float distMin, float distMax)
{
static const sint32 mbMin = -10000;
static const sint32 mbMax = 0;
sint32 rolloffMb = ISource::computeManualRollOff(mbMax, mbMin, mbMax, alpha, sqrdist, distMin, distMax);
float rolloffGain = (float)pow(10.0, (double)rolloffMb / 2000.0);
clamp(rolloffGain, 0.0f, 1.0f);
return rolloffGain;
}
} // NLSOUND
/* end of file */