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Added: Specific code for amplitude based rolloff to avoid unneccesary log10 and pow calls and improve performance

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--HG--
branch : sound_dev
This commit is contained in:
kaetemi 2012-06-03 01:50:53 +02:00
parent 221d04642a
commit 19d2d91f86
1 changed files with 50 additions and 3 deletions
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53
code/nel/src/sound/driver/source.cpp
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@ -65,12 +65,59 @@ sint32 ISource::computeManualRollOff(sint32 volumeMB, sint32 mbMin, sint32 mbMax
// 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;
/*static const sint mbMin = -10000;
static const sint 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;
return rolloffGain;*/
static const double mbMin = -10000;
static const double mbMax = 0;
if (sqrdist < distMin * distMin)
{
// no attenuation
return 1.0f;
}
else
{
double dist = (double)sqrt(sqrdist);
if (alpha < 0.0f)
{
// inverse distance rolloff
float rolloff = distMin / dist;
if (alpha <= -1.0f) return rolloff;
double mb = mbMin * (dist - distMin) / (distMax - distMin);
float mbrolloff = (float)pow(10.0, (double)mb / 2000.0);
return ((1.0 + alpha) * mbrolloff - alpha * rolloff);
}
else
{
if (sqrdist > distMax * distMax)
{
// full attenuation
return 0.0f;
}
if (alpha == 0.0f)
{
// linearly descending volume on a dB scale
double mb = mbMin * (dist - distMin) / (distMax - distMin);
return (float)pow(10.0, (double)mb / 2000.0);
}
else // if (alpha > 0.0f)
{
// linear distance rolloff
float rolloff = (distMax - dist) / (distMax - distMin);
if (alpha >= 1.0f) return rolloff;
double mb = mbMin * (dist - distMin) / (distMax - distMin);
float mbrolloff = (float)pow(10.0, (double)mb / 2000.0);
return ((1.0 - alpha) * mbrolloff + alpha * rolloff);
}
}
}
}
} // NLSOUND