109 lines
3.4 KiB
C++
109 lines
3.4 KiB
C++
//========= Copyright Valve Corporation, All rights reserved. ============//
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//
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// Purpose: Sound code shared between server and client
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//
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//=============================================================================//
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#include <math.h>
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#include "convar.h"
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#include "sound.h"
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ConVar snd_refdist( "snd_refdist", "36", FCVAR_CHEAT);
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ConVar snd_refdb( "snd_refdb", "60", FCVAR_CHEAT );
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ConVar snd_foliage_db_loss( "snd_foliage_db_loss", "4", FCVAR_CHEAT );
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ConVar snd_gain( "snd_gain", "1", FCVAR_CHEAT );
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ConVar snd_gain_max( "snd_gain_max", "1", FCVAR_CHEAT );
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ConVar snd_gain_min( "snd_gain_min", "0.01", FCVAR_CHEAT );
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// calculate gain based on atmospheric attenuation.
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// as gain excedes threshold, round off (compress) towards 1.0 using spline
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#define SND_GAIN_COMP_EXP_MAX 2.5f // Increasing SND_GAIN_COMP_EXP_MAX fits compression curve more closely
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// to original gain curve as it approaches 1.0.
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#define SND_GAIN_COMP_EXP_MIN 0.8f
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#define SND_GAIN_COMP_THRESH 0.5f // gain value above which gain curve is rounded to approach 1.0
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#define SND_DB_MAX 140.0f // max db of any sound source
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#define SND_DB_MED 90.0f // db at which compression curve changes
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#define SNDLVL_TO_DIST_MULT( sndlvl ) ( sndlvl ? ((pow( 10.0f, snd_refdb.GetFloat() / 20 ) / pow( 10.0f, (float)sndlvl / 20 )) / snd_refdist.GetFloat()) : 0 )
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#define DIST_MULT_TO_SNDLVL( dist_mult ) (soundlevel_t)(int)( dist_mult ? ( 20 * log10( pow( 10.0f, snd_refdb.GetFloat() / 20 ) / (dist_mult * snd_refdist.GetFloat()) ) ) : 0 )
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float SND_GetGainFromMult( float gain, float dist_mult, vec_t dist )
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{
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// test additional attenuation
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// at 30c, 14.7psi, 60% humidity, 1000Hz == 0.22dB / 100ft.
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// dense foliage is roughly 2dB / 100ft
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float additional_dB_loss = snd_foliage_db_loss.GetFloat() * (dist / 1200);
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float additional_dist_mult = pow( 10.0f, additional_dB_loss / 20);
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float relative_dist = dist * dist_mult * additional_dist_mult;
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// hard code clamp gain to 10x normal (assumes volume and external clipping)
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if (relative_dist > 0.1)
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{
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gain *= (1/relative_dist);
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}
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else
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gain *= 10.0;
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// if gain passess threshold, compress gain curve such that gain smoothly approaches 1.0
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if ( gain > SND_GAIN_COMP_THRESH )
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{
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float snd_gain_comp_power = SND_GAIN_COMP_EXP_MAX;
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soundlevel_t sndlvl = DIST_MULT_TO_SNDLVL( dist_mult );
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float Y;
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// decrease compression curve fit for higher sndlvl values
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if ( sndlvl > SND_DB_MED )
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{
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// snd_gain_power varies from max to min as sndlvl varies from 90 to 140
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snd_gain_comp_power = RemapVal ((float)sndlvl, SND_DB_MED, SND_DB_MAX, SND_GAIN_COMP_EXP_MAX, SND_GAIN_COMP_EXP_MIN);
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}
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// calculate crossover point
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Y = -1.0 / ( pow(SND_GAIN_COMP_THRESH, snd_gain_comp_power) * (SND_GAIN_COMP_THRESH - 1) );
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// calculate compressed gain
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gain = 1.0 - 1.0 / (Y * pow( gain, snd_gain_comp_power ) );
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gain = gain * snd_gain_max.GetFloat();
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}
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if ( gain < snd_gain_min.GetFloat() )
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{
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// sounds less than snd_gain_min fall off to 0 in distance it took them to fall to snd_gain_min
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gain = snd_gain_min.GetFloat() * (2.0 - relative_dist * snd_gain_min.GetFloat());
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if (gain <= 0.0)
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gain = 0.001; // don't propagate 0 gain
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}
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return gain;
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}
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float S_GetGainFromSoundLevel( soundlevel_t soundlevel, vec_t dist )
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{
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float gain = snd_gain.GetFloat();
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float dist_mult = SNDLVL_TO_DIST_MULT( soundlevel );
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if ( dist_mult )
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{
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gain = SND_GetGainFromMult( gain, dist_mult, dist );
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}
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return gain;
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}
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