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77 lines
2.6 KiB
C++
77 lines
2.6 KiB
C++
// NeL - MMORPG Framework <http://dev.ryzom.com/projects/nel/>
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// Copyright (C) 2010 Winch Gate Property Limited
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License as
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// published by the Free Software Foundation, either version 3 of the
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// License, or (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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#include "nel/sound/driver/source.h"
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#include "nel/misc/common.h"
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using namespace NLMISC;
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namespace NLSOUND
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{
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// common method used only with OptionManualRolloff. return the volume in 1/100th DB ( = mB) modified
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sint32 ISource::computeManualRollOff(sint32 volumeMB, sint32 mbMin, sint32 mbMax, double alpha, float sqrdist, float distMin, float distMax)
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{
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if (sqrdist < distMin * distMin)
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{
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// no attenuation
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return volumeMB;
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}
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else if (sqrdist > distMax * distMax)
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{
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// full attenuation
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return mbMin;
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}
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else
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{
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double dist = (double) sqrt(sqrdist);
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// linearly descending volume on a dB scale
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double db1 = mbMin * (dist - distMin) / (distMax - distMin);
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if (alpha == 0.0) {
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volumeMB += (sint32) db1;
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} else if (alpha > 0.0) {
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double amp2 = 0.0001 + 0.9999 * (distMax - dist) / (distMax - distMin); // linear amp between 0.00001 and 1.0
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double db2 = 2000.0 * log10(amp2); // convert to 1/100th decibels
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volumeMB += (sint32) ((1.0 - alpha) * db1 + alpha * db2);
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} else if (alpha < 0.0) {
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double amp3 = distMin / dist; // linear amplitude is 1/distance
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double db3 = 2000.0 * log10(amp3); // convert to 1/100th decibels
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volumeMB += (sint32) ((1.0 + alpha) * db1 - alpha * db3);
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}
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clamp(volumeMB, mbMin, mbMax);
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return volumeMB;
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}
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}
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// common method used only with OptionManualRolloff. return the rolloff in amplitude ratio (gain)
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float ISource::computeManualRolloff(double alpha, float sqrdist, float distMin, float distMax)
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{
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static const sint32 mbMin = -10000;
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static const sint32 mbMax = 0;
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sint32 rolloffMb = ISource::computeManualRollOff(mbMax, mbMin, mbMax, alpha, sqrdist, distMin, distMax);
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float rolloffGain = (float)pow(10.0, (double)rolloffMb / 2000.0);
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clamp(rolloffGain, 0.0f, 1.0f);
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return rolloffGain;
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}
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} // NLSOUND
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/* end of file */
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