Modified source engine (2017) developed by valve and leaked in 2020. Not for commercial purporses
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//========= Copyright Valve Corporation, All rights reserved. ============//
//
// Purpose:
// Information about algorithmic stuff that can occur on both client + server
//
// In order to reduce network traffic, it's possible to create a algorithms
// that will work on both the client and the server and be totally repeatable.
// All we need do is to send down initial conditions and let the algorithm
// compute the values at various times. Note that this algorithm will be called
// at different times with different frequencies on the client and server.
//
// The trick here is that in order for it to be repeatable, the algorithm either
// cannot depend on random numbers, or, if it does, we need to make sure that
// the random numbers generated are effectively done at the beginning of time,
// so that differences in frame rate on client and server won't matter. It also
// is important that the initial state sent across the network is identical
// bitwise so that we produce the exact same results. Therefore no compression
// should be used in the datatables.
//
// Note also that each algorithm must have its own random number stream so that
// it cannot possibly interact with other code using random numbers that will
// be called at various different intervals on the client + server. Use the
// CUniformRandomStream class for this.
//
// There are two types of client-server neutral code: Code that doesn't interact
// with player prediction, and code that does. The code that doesn't interact
// with player prediction simply has to be able to produce the result f(time)
// where time is monotonically increasing. For prediction, we have to produce
// the result f(time) where time does *not* monotonically increase (time can be
// anywhere between the "current" time and the prior 10 seconds).
//
// Code that is not used by player prediction can maintain state because later
// calls will always compute the value at some future time. This computation can
// use random number generation, but with the following restriction: Your code
// must generate exactly the same number of random numbers regardless of how
// frequently the code is called.
//
// In specific, this means that all random numbers used must either be computed
// at init time, or must be used in an 'event-based form'. Namely, use random
// numbers to compute the time at which events occur and the random inputs for
// those events. When simulating forward, you must simulate all intervening
// time and generate the same number of random numbers.
//
// For functions planned to be used by player prediction, one method is to use
// some sort of stateless computation (where the only states are the initial
// state and time). Note that random number generators have state implicit in
// the number of calls made to that random number generator, and therefore you
// cannot call a random number generator unless you are able to
//
// 1) Use a random number generator that can return the ith random number, namely:
//
// float r = random( i ); // i == the ith number in the random sequence
//
// 2) Be able to accurately know at any given time t how many random numbers
// have already been generated (namely, compute the i in part 1 above).
//
// There is another alternative for code meant to be used by player prediction:
// you could just store a history of 'events' from which you could completely
// determine the value of f(time). That history would need to be at least 10
// seconds long, which is guaranteed to be longer than the amount of time that
// prediction would need. I've written a class which I haven't tested yet (but
// will be using soon) called CTimedEventQueue (currently located in
// env_wind_shared.h) which I plan to use to solve my problem (getting wind to
// blow players).
//
//=============================================================================//
#include "cbase.h"
#include "env_wind_shared.h"
#include "soundenvelope.h"
#include "IEffects.h"
#include "engine/IEngineSound.h"
#include "sharedInterface.h"
// memdbgon must be the last include file in a .cpp file!!!
#include "tier0/memdbgon.h"
//-----------------------------------------------------------------------------
// globals
//-----------------------------------------------------------------------------
static Vector s_vecWindVelocity( 0, 0, 0 );
CEnvWindShared::CEnvWindShared() : m_WindAveQueue(10), m_WindVariationQueue(10)
{
m_pWindSound = NULL;
}
CEnvWindShared::~CEnvWindShared()
{
if (m_pWindSound)
{
CSoundEnvelopeController::GetController().Shutdown( m_pWindSound );
}
}
void CEnvWindShared::Init( int nEntIndex, int iRandomSeed, float flTime,
int iInitialWindYaw, float flInitialWindSpeed )
{
m_iEntIndex = nEntIndex;
m_flWindAngleVariation = m_flWindSpeedVariation = 1.0f;
m_flStartTime = m_flSimTime = m_flSwitchTime = m_flVariationTime = flTime;
m_iWindSeed = iRandomSeed;
m_Stream.SetSeed( iRandomSeed );
m_WindVariationStream.SetSeed( iRandomSeed );
m_iWindDir = m_iInitialWindDir = iInitialWindYaw;
m_flAveWindSpeed = m_flWindSpeed = m_flInitialWindSpeed = flInitialWindSpeed;
/*
// Cache in the wind sound...
if (!g_pEffects->IsServer())
{
CSoundEnvelopeController &controller = CSoundEnvelopeController::GetController();
m_pWindSound = controller.SoundCreate( -1, CHAN_STATIC,
"EnvWind.Loop", ATTN_NONE );
controller.Play( m_pWindSound, 0.0f, 100 );
}
*/
// Next time a change happens (which will happen immediately), it'll stop gusting
m_bGusting = true;
}
//-----------------------------------------------------------------------------
// Computes wind variation
//-----------------------------------------------------------------------------
#define WIND_VARIATION_UPDATE_TIME 0.1f
void CEnvWindShared::ComputeWindVariation( float flTime )
{
// The wind variation is updated every 10th of a second..
while( flTime >= m_flVariationTime )
{
m_flWindAngleVariation = m_WindVariationStream.RandomFloat( -10, 10 );
m_flWindSpeedVariation = 1.0 + m_WindVariationStream.RandomFloat( -0.2, 0.2 );
m_flVariationTime += WIND_VARIATION_UPDATE_TIME;
}
}
//-----------------------------------------------------------------------------
// Updates the wind sound
//-----------------------------------------------------------------------------
void CEnvWindShared::UpdateWindSound( float flTotalWindSpeed )
{
if (!g_pEffects->IsServer())
{
float flDuration = random->RandomFloat( 1.0f, 2.0f );
CSoundEnvelopeController &controller = CSoundEnvelopeController::GetController();
// FIXME: Tweak with these numbers
float flNormalizedWindSpeed = flTotalWindSpeed / 150.0f;
if (flNormalizedWindSpeed > 1.0f)
flNormalizedWindSpeed = 1.0f;
float flPitch = 120 * Bias( flNormalizedWindSpeed, 0.3f ) + 100;
float flVolume = 0.3f * Bias( flNormalizedWindSpeed, 0.3f ) + 0.7f;
controller.SoundChangePitch( m_pWindSound, flPitch, flDuration );
controller.SoundChangeVolume( m_pWindSound, flVolume, flDuration );
}
}
//-----------------------------------------------------------------------------
// Updates the wind speed
//-----------------------------------------------------------------------------
#define WIND_ACCELERATION 150.0f // wind speed can accelerate this many units per second
#define WIND_DECELERATION 15.0f // wind speed can decelerate this many units per second
float CEnvWindShared::WindThink( float flTime )
{
// NOTE: This algorithm can be client-server neutal because we're using
// the random number generator to generate *time* at which the wind changes.
// We therefore need to structure the algorithm so that no matter the
// frequency of calls to this function we produce the same wind speeds...
ComputeWindVariation( flTime );
while (true)
{
// First, simulate up to the next switch time...
float flTimeToSwitch = m_flSwitchTime - m_flSimTime;
float flMaxDeltaTime = flTime - m_flSimTime;
bool bGotToSwitchTime = (flMaxDeltaTime > flTimeToSwitch);
float flSimDeltaTime = bGotToSwitchTime ? flTimeToSwitch : flMaxDeltaTime;
// Now that we've chosen
// either ramp up, or sleep till change
bool bReachedSteadyState = true;
if ( m_flAveWindSpeed > m_flWindSpeed )
{
m_flWindSpeed += WIND_ACCELERATION * flSimDeltaTime;
if (m_flWindSpeed > m_flAveWindSpeed)
m_flWindSpeed = m_flAveWindSpeed;
else
bReachedSteadyState = false;
}
else if ( m_flAveWindSpeed < m_flWindSpeed )
{
m_flWindSpeed -= WIND_DECELERATION * flSimDeltaTime;
if (m_flWindSpeed < m_flAveWindSpeed)
m_flWindSpeed = m_flAveWindSpeed;
else
bReachedSteadyState = false;
}
// Update the sim time
// If we didn't get to a switch point, then we're done simulating for now
if (!bGotToSwitchTime)
{
m_flSimTime = flTime;
// We're about to exit, let's set the wind velocity...
QAngle vecWindAngle( 0, m_iWindDir + m_flWindAngleVariation, 0 );
AngleVectors( vecWindAngle, &s_vecWindVelocity );
float flTotalWindSpeed = m_flWindSpeed * m_flWindSpeedVariation;
s_vecWindVelocity *= flTotalWindSpeed;
// If we reached a steady state, we don't need to be called until the switch time
// Otherwise, we should be called immediately
// FIXME: If we ever call this from prediction, we'll need
// to only update the sound if it's a new time
// Or, we'll need to update the sound elsewhere.
// Update the sound....
// UpdateWindSound( flTotalWindSpeed );
// Always immediately call, the wind is forever varying
return ( flTime + 0.01f );
}
m_flSimTime = m_flSwitchTime;
// Switch gusting state..
if( m_bGusting )
{
// wind is gusting, so return to normal wind
m_flAveWindSpeed = m_Stream.RandomInt( m_iMinWind, m_iMaxWind );
// set up for another gust later
m_bGusting = false;
m_flSwitchTime += m_flMinGustDelay + m_Stream.RandomFloat( 0, m_flMaxGustDelay );
#ifndef CLIENT_DLL
m_OnGustEnd.FireOutput( NULL, NULL );
#endif
}
else
{
// time for a gust.
m_flAveWindSpeed = m_Stream.RandomInt( m_iMinGust, m_iMaxGust );
// change wind direction, maybe a lot
m_iWindDir = anglemod( m_iWindDir + m_Stream.RandomInt(-m_iGustDirChange, m_iGustDirChange) );
// set up to stop the gust in a short while
m_bGusting = true;
#ifndef CLIENT_DLL
m_OnGustStart.FireOutput( NULL, NULL );
#endif
// !!!HACKHACK - gust duration tied to the length of a particular wave file
m_flSwitchTime += m_flGustDuration;
}
}
}
//-----------------------------------------------------------------------------
// Method to reset windspeed..
//-----------------------------------------------------------------------------
void ResetWindspeed()
{
s_vecWindVelocity.Init( 0, 0, 0 );
}
//-----------------------------------------------------------------------------
// Method to sample the windspeed at a particular time
//-----------------------------------------------------------------------------
void GetWindspeedAtTime( float flTime, Vector &vecVelocity )
{
// For now, ignore history and time.. fix later when we use wind to affect
// client-side prediction
VectorCopy( s_vecWindVelocity, vecVelocity );
}