// cg_particles.c -- the particle system

/*
 *  Portions Copyright (C) 2000-2001 Tim Angus
 *
 *  This program is free software; you can redistribute it and/or modify it
 *  under the terms of the OSML - Open Source Modification License v1.0 as
 *  described in the file COPYING which is distributed with this source
 *  code.
 *
 *  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.
 */

#include "cg_local.h"

static baseParticleSystem_t   baseParticleSystems[ MAX_BASEPARTICLE_SYSTEMS ];
static baseParticleEjector_t  baseParticleEjectors[ MAX_BASEPARTICLE_EJECTORS ];
static baseParticle_t         baseParticles[ MAX_BASEPARTICLES ];
static int                    numBaseParticleSystems = 0;
static int                    numBaseParticleEjectors = 0;
static int                    numBaseParticles = 0;

static particleSystem_t     particleSystems[ MAX_PARTICLE_SYSTEMS ];
static particleEjector_t    particleEjectors[ MAX_PARTICLE_EJECTORS ];
static particle_t           particles[ MAX_PARTICLES ];
static particle_t           sortParticles[ MAX_PARTICLES ];

/*
===============
CG_LerpValues

Lerp between two values
===============
*/
static float CG_LerpValues( float a, float b, float f )
{
  if( b == PARTICLES_SAME_AS_INITIAL )
    return a;
  else
    return ( (a) + (f) * ( (b) - (a) ) );
}

/*
===============
CG_RandomiseValue

Randomise some value by some variance
===============
*/
static float CG_RandomiseValue( float value, float variance )
{
  if( value != 0.0f )
    return value * ( 1.0f + ( random( ) * variance ) );
  else
    return random( ) * variance;
}

/*
===============
CG_SpreadVector

Randomly spread a vector by some amount
===============
*/
static void CG_SpreadVector( vec3_t v, float spread )
{
  vec3_t  p, r1, r2;
  float   randomSpread = crandom( ) * spread;
  float   randomRotation = random( ) * 360.0f;

  PerpendicularVector( p, v );

  RotatePointAroundVector( r1, p, v, randomSpread );
  RotatePointAroundVector( r2, v, r1, randomRotation );

  VectorCopy( r2, v );
}

/*
===============
CG_SpawnNewParticle

Introduce a new particle into the world
===============
*/
static particle_t *CG_SpawnNewParticle( baseParticle_t *bp, particleEjector_t *parent )
{
  int                     i, j, start;
  particle_t              *p = NULL;
  particleEjector_t       *pe = parent;
  particleSystem_t        *ps = parent->parent;
  vec3_t                  forward;
  centity_t               *cent = &cg_entities[ ps->attachment.centNum ];

  for( i = 0; i < MAX_PARTICLES; i++ )
  {
    p = &particles[ i ];
    
    if( !p->valid )
    {
      memset( p, 0, sizeof( particle_t ) );

      //found a free slot
      p->class = bp;
      p->parent = pe;

      p->birthTime = cg.time;
      p->lifeTime = (int)CG_RandomiseValue( (float)bp->lifeTime, bp->lifeTimeRandFrac );
      
      p->radius.delay = (int)CG_RandomiseValue( (float)bp->radius.delay, bp->radius.delayRandFrac );
      p->radius.initial = CG_RandomiseValue( bp->radius.initial, bp->radius.initialRandFrac );
      p->radius.final = CG_RandomiseValue( bp->radius.final, bp->radius.finalRandFrac );
      
      p->alpha.delay = (int)CG_RandomiseValue( (float)bp->alpha.delay, bp->alpha.delayRandFrac );
      p->alpha.initial = CG_RandomiseValue( bp->alpha.initial, bp->alpha.initialRandFrac );
      p->alpha.final = CG_RandomiseValue( bp->alpha.final, bp->alpha.finalRandFrac );
      
      p->rotation.delay = (int)CG_RandomiseValue( (float)bp->rotation.delay, bp->rotation.delayRandFrac );
      p->rotation.initial = CG_RandomiseValue( bp->rotation.initial, bp->rotation.initialRandFrac );
      p->rotation.final = CG_RandomiseValue( bp->rotation.final, bp->rotation.finalRandFrac );
      
      switch( ps->attachType )
      {
        case PSA_STATIC:
          if( !ps->attachment.staticValid )
            return NULL;
          
          VectorCopy( ps->attachment.origin, p->origin );
          break;

        case PSA_TAG:
          if( !ps->attachment.tagValid )
            return NULL;
          
          AxisCopy( axisDefault, ps->attachment.re.axis );
          CG_PositionRotatedEntityOnTag( &ps->attachment.re, &ps->attachment.parent,
                                         ps->attachment.model, ps->attachment.tagName );
          VectorCopy( ps->attachment.re.origin, p->origin );
          break;
        
        case PSA_CENT_ORIGIN:
          if( !ps->attachment.centValid )
            return NULL;
          
          VectorCopy( cent->lerpOrigin, p->origin );
          break;
      }
        
      VectorAdd( p->origin, bp->displacement, p->origin );
      
      for( j = 0; j <= 2; j++ )
        p->origin[ j ] += ( crandom( ) * bp->randDisplacement );

      switch( bp->velMoveType )
      {
        case PMT_STATIC:
          
          if( bp->velMoveValues.dirType == PMD_POINT )
            VectorSubtract( bp->velMoveValues.point, p->origin, p->velocity );
          else if( bp->velMoveValues.dirType == PMD_LINEAR )
            VectorCopy( bp->velMoveValues.dir, p->velocity );
          
          break;

        case PMT_TAG:
          
          if( !ps->attachment.tagValid )
            return NULL;
          
          if( bp->velMoveValues.dirType == PMD_POINT )
            VectorSubtract( ps->attachment.re.origin, p->origin, p->velocity );
          else if( bp->velMoveValues.dirType == PMD_LINEAR )
            VectorCopy( ps->attachment.re.axis[ 0 ], p->velocity );
          
          break;

        case PMT_CENT_ANGLES:
          
          if( !ps->attachment.centValid )
            return NULL;
          
          if( bp->velMoveValues.dirType == PMD_POINT )
            VectorSubtract( cent->lerpOrigin, p->origin, p->velocity );
          else if( bp->velMoveValues.dirType == PMD_LINEAR )
          {
            AngleVectors( cent->lerpAngles, forward, NULL, NULL );
            VectorCopy( forward, p->velocity );
          }
          
          break;
          
      case PMT_NORMAL:
        
        if( !ps->attachment.normalValid )
          return NULL;
        
        VectorCopy( ps->attachment.normal, p->velocity );

        //normal displacement
        VectorNormalize( p->velocity );
        VectorMA( p->origin, bp->normalDisplacement, p->velocity, p->origin );
        
        break;
      }
            
      VectorNormalize( p->velocity );
      CG_SpreadVector( p->velocity, bp->velMoveValues.dirRandAngle );
      VectorScale( p->velocity,
                   CG_RandomiseValue( bp->velMoveValues.mag, bp->velMoveValues.magRandFrac ),
                   p->velocity );

      if( ps->attachment.centValid )
      {
        VectorMA( p->velocity,
                  CG_RandomiseValue( bp->velMoveValues.parentVelFrac, bp->velMoveValues.parentVelFracRandFrac ),
                  cent->currentState.pos.trDelta, p->velocity );
      }
          
      p->lastEvalTime = cg.time;

      p->valid = qtrue;
      
      break;
    }
  }

  return p;
}


/*
===============
CG_SpawnNewParticles

Check if there are any ejectors that should be
introducing new particles
===============
*/
static void CG_SpawnNewParticles( void )
{
  int                   i, j;
  particle_t            *p;
  particleSystem_t      *ps;
  particleEjector_t     *pe;
  baseParticleEjector_t *bpe;
  float                 lerpFrac;
  int                   count;

  for( i = 0; i < MAX_PARTICLE_EJECTORS; i++ )
  {
    pe = &particleEjectors[ i ];
    ps = pe->parent;

    if( pe->valid )
    {
      //a non attached particle system can't make particles
      if( !ps->attached )
        continue;

      bpe = particleEjectors[ i ].class;

      //if this system is scheduled for removal don't make any new particles
      if( !ps->lazyRemove )
      {
        while( pe->nextEjectionTime <= cg.time &&
               ( pe->count > 0 || pe->totalParticles == PARTICLES_INFINITE ) )
        {
          for( j = 0; j < bpe->numParticles; j++ )
            CG_SpawnNewParticle( bpe->particles[ j ], pe );
          
          if( pe->count > 0 )
            pe->count--;

          //calculate next ejection time
          lerpFrac = 1.0 - ( (float)pe->count / (float)pe->totalParticles );
          pe->nextEjectionTime = cg.time + CG_RandomiseValue( 
              CG_LerpValues( pe->ejectPeriod.initial,
                             pe->ejectPeriod.final,
                             lerpFrac ),
              pe->ejectPeriod.randFrac );
        }
      }

      if( pe->count == 0 || ps->lazyRemove )
      {
        count = 0;

        //wait for child particles to die before declaring this pe invalid
        for( j = 0; j < MAX_PARTICLES; j++ )
        {
          p = &particles[ j ];
          
          if( p->valid && p->parent == pe )
            count++;
        }

        if( !count )
          pe->valid = qfalse;
      }
    }
  }
}


/*
===============
CG_SpawnNewParticleEjector

Allocate a new particle ejector
===============
*/
static particleEjector_t *CG_SpawnNewParticleEjector( baseParticleEjector_t *bpe,
                                                      particleSystem_t *parent )
{
  int                     i, start;
  particleEjector_t       *pe = NULL;
  particleSystem_t        *ps = parent;

  for( i = 0; i < MAX_PARTICLE_EJECTORS; i++ )
  {
    pe = &particleEjectors[ i ];
    
    if( !pe->valid )
    {
      memset( pe, 0, sizeof( particleEjector_t ) );

      //found a free slot
      pe->class = bpe;
      pe->parent = ps;

      pe->ejectPeriod.initial = bpe->eject.initial;
      pe->ejectPeriod.final = bpe->eject.final;
      pe->ejectPeriod.randFrac = bpe->eject.randFrac;

      pe->nextEjectionTime = cg.time +
        (int)CG_RandomiseValue( (float)bpe->eject.delay, bpe->eject.delayRandFrac );
      pe->count = pe->totalParticles =
        (int)CG_RandomiseValue( (float)bpe->totalParticles, bpe->totalParticlesRandFrac );

      pe->valid = qtrue;
      
      if( cg_debugParticles.integer >= 1 )
        CG_Printf( "PE %s created\n", ps->class->name );
      
      break;
    }
  }

  return pe;
}


/*
===============
CG_SpawnNewParticleSystem

Allocate a new particle system
===============
*/
particleSystem_t *CG_SpawnNewParticleSystem( qhandle_t psHandle )
{
  int                   i, j, start;
  particleSystem_t      *ps = NULL;
  baseParticleSystem_t  *bps = &baseParticleSystems[ psHandle - 1 ];

  if( !bps->registered )
  {
    CG_Printf( S_COLOR_RED "ERROR: a particle system has not been registered yet\n" );
    return NULL;
  }
    
  for( i = 0; i < MAX_PARTICLE_SYSTEMS; i++ )
  {
    ps = &particleSystems[ i ];
    
    if( !ps->valid )
    {
      memset( ps, 0, sizeof( particleSystem_t ) );

      //found a free slot
      ps->class = bps;

      ps->valid = qtrue;
      ps->lazyRemove = qfalse;
      
      for( j = 0; j < bps->numEjectors; j++ )
        CG_SpawnNewParticleEjector( bps->ejectors[ j ], ps );

      if( cg_debugParticles.integer >= 1 )
        CG_Printf( "PS %s created\n", bps->name );

      break;
    }
  }

  return ps;
}

/*
===============
CG_RegisterParticleSystem

Load the shaders required for a particle system
===============
*/
qhandle_t CG_RegisterParticleSystem( char *name )
{
  int                   i, j, k, l;
  baseParticleSystem_t  *bps;
  baseParticleEjector_t *bpe;
  baseParticle_t        *bp;

  for( i = 0; i < MAX_PARTICLE_SYSTEMS; i++ )
  {
    bps = &baseParticleSystems[ i ];
    
    if( !strcmp( bps->name, name ) )
    {
      for( j = 0; j < bps->numEjectors; j++ )
      {
        bpe = bps->ejectors[ j ];
        
        for( l = 0; l < bpe->numParticles; l++ )
        {
          bp = bpe->particles[ l ];

          for( k = 0; k < bp->numFrames; k++ )
            bp->shaders[ k ] = trap_R_RegisterShader( bp->shaderNames[ k ] );
        }
      }

      bps->registered = qtrue;

      //avoid returning 0
      return i + 1;
    }
  }

  CG_Printf( S_COLOR_RED "ERROR: failed to load particle system %s\n", name );
  return 0;
}


/*
===============
atof_neg

atof with an allowance for negative values
===============
*/
static float atof_neg( char *token, qboolean allowNegative )
{
  float value;

  value = atof( token );

  if( !allowNegative && value < 0.0f )
  {
    CG_Printf( S_COLOR_YELLOW "WARNING: negative value %f is now allowed here, "
                              "replaced with 1.0f\n", value );
    value = 1.0f;
  }

  return value;
}

/*
===============
atoi_neg

atoi with an allowance for negative values
===============
*/
static int atoi_neg( char *token, qboolean allowNegative )
{
  int value;

  value = atoi( token );

  if( !allowNegative && value < 0 )
  {
    CG_Printf( S_COLOR_YELLOW "WARNING: negative value %d is now allowed here, "
                              "replaced with 1\n", value );
    value = 1;
  }

  return value;
}


/*
===============
CG_ParseValueAndVariance

Parse a value and its random variance
===============
*/
static void CG_ParseValueAndVariance( char *token, float *value, float *variance, qboolean allowNegative )
{
  char  valueBuffer[ 16 ];
  char  varianceBuffer[ 16 ];
  char  *variancePtr = NULL, *varEndPointer = NULL;
  float localValue = 0.0f;
  float localVariance = 0.0f;

  Q_strncpyz( valueBuffer, token, sizeof( valueBuffer ) );
  Q_strncpyz( varianceBuffer, token, sizeof( varianceBuffer ) );

  variancePtr = strchr( valueBuffer, '~' );
  
  //variance included
  if( variancePtr )
  {
    variancePtr[ 0 ] = '\0';
    variancePtr++;

    localValue = atof_neg( valueBuffer, allowNegative );
    
    varEndPointer = strchr( variancePtr, '%' );

    if( varEndPointer )
    {
      varEndPointer[ 0 ] = '\0';
      localVariance = atof_neg( variancePtr, qfalse ) / 100.0f;
    }
    else
    {
      if( localValue != 0.0f )
        localVariance = atof_neg( variancePtr, qfalse ) / localValue;
      else
        localVariance = atof_neg( variancePtr, qfalse );
    }
  }
  else
    localValue = atof_neg( valueBuffer, allowNegative );

  if( value != NULL )
    *value = localValue;

  if( variance != NULL )
    *variance = localVariance;
}


/*
===============
CG_ParseParticle

Parse a particle section
===============
*/
static qboolean CG_ParseParticle( baseParticle_t *bp, char **text_p )
{
  char  *token;
  float number, randFrac;
  int   i;

  // read optional parameters
  while( 1 )
  {
    token = COM_Parse( text_p );
    
    if( !token )
      break;

    if( !Q_stricmp( token, "" ) )
      return qfalse;

    if( !Q_stricmp( token, "bounce" ) )
    {
      token = COM_Parse( text_p );
      if( !token )
        break;

      if( !Q_stricmp( token, "cull" ) )
      {
        bp->bounceCull = qtrue;
        
        bp->bounceFrac = -1.0f;
        bp->bounceFracRandFrac = 0.0f;
      }
      else
      {
        CG_ParseValueAndVariance( token, &number, &randFrac, qfalse );

        bp->bounceFrac = number;
        bp->bounceFracRandFrac = randFrac;
      }

      continue;
    }
    else if( !Q_stricmp( token, "shader" ) )
    {
      token = COM_Parse( text_p );
      if( !token )
        break;
      
      if( !Q_stricmp( token, "sync" ) )
        bp->framerate = 0.0f;
      else
        bp->framerate = atof_neg( token, qfalse );

      token = COM_ParseExt( text_p, qfalse );

      while( token && token[ 0 ] != 0 )
      {
        Q_strncpyz( bp->shaderNames[ bp->numFrames++ ], token, MAX_QPATH );
        token = COM_ParseExt( text_p, qfalse );
      }
      
      if( !token )
        break;
      
      continue;
    }
    ///
    else if( !Q_stricmp( token, "velocityType" ) )
    {
      token = COM_Parse( text_p );
      if( !token )
        break;
      
      if( !Q_stricmp( token, "static" ) )
        bp->velMoveType = PMT_STATIC;
      else if( !Q_stricmp( token, "tag" ) )
        bp->velMoveType = PMT_TAG;
      else if( !Q_stricmp( token, "cent" ) )
        bp->velMoveType = PMT_CENT_ANGLES;
      else if( !Q_stricmp( token, "normal" ) )
        bp->velMoveType = PMT_NORMAL;

      continue;
    }
    else if( !Q_stricmp( token, "velocityDir" ) )
    {
      token = COM_Parse( text_p );
      if( !token )
        break;
      
      if( !Q_stricmp( token, "linear" ) )
        bp->velMoveValues.dirType = PMD_LINEAR;
      else if( !Q_stricmp( token, "point" ) )
        bp->velMoveValues.dirType = PMD_POINT;

      continue;
    }
    else if( !Q_stricmp( token, "velocityMagnitude" ) )
    {
      token = COM_Parse( text_p );
      if( !token )
        break;
      
      CG_ParseValueAndVariance( token, &number, &randFrac, qfalse );

      bp->velMoveValues.mag = number;
      bp->velMoveValues.magRandFrac = randFrac;

      continue;
    }
    else if( !Q_stricmp( token, "parentVelocityFraction" ) )
    {
      token = COM_Parse( text_p );
      if( !token )
        break;
      
      CG_ParseValueAndVariance( token, &number, &randFrac, qfalse );

      bp->velMoveValues.parentVelFrac = number;
      bp->velMoveValues.parentVelFracRandFrac = randFrac;

      continue;
    }
    else if( !Q_stricmp( token, "velocity" ) )
    {
      for( i = 0; i <= 2; i++ )
      {
        token = COM_Parse( text_p );
        if( !token )
          break;
        
        bp->velMoveValues.dir[ i ] = atof_neg( token, qtrue );
      }
      
      token = COM_Parse( text_p );
      if( !token )
        break;
      
      CG_ParseValueAndVariance( token, NULL, &randFrac, qfalse );

      bp->velMoveValues.dirRandAngle = randFrac;
      
      continue;
    }
    else if( !Q_stricmp( token, "velocityPoint" ) )
    {
      for( i = 0; i <= 2; i++ )
      {
        token = COM_Parse( text_p );
        if( !token )
          break;
        
        bp->velMoveValues.point[ i ] = atof_neg( token, qtrue );
      }
      
      token = COM_Parse( text_p );
      if( !token )
        break;
      
      CG_ParseValueAndVariance( token, NULL, &randFrac, qfalse );

      bp->velMoveValues.pointRandAngle = randFrac;
      
      continue;
    }
    ///
    else if( !Q_stricmp( token, "accelerationType" ) )
    {
      token = COM_Parse( text_p );
      if( !token )
        break;
      
      if( !Q_stricmp( token, "static" ) )
        bp->accMoveType = PMT_STATIC;
      else if( !Q_stricmp( token, "tag" ) )
        bp->accMoveType = PMT_TAG;
      else if( !Q_stricmp( token, "cent" ) )
        bp->accMoveType = PMT_CENT_ANGLES;
      else if( !Q_stricmp( token, "normal" ) )
        bp->accMoveType = PMT_NORMAL;

      continue;
    }
    else if( !Q_stricmp( token, "accelerationDir" ) )
    {
      token = COM_Parse( text_p );
      if( !token )
        break;
      
      if( !Q_stricmp( token, "linear" ) )
        bp->accMoveValues.dirType = PMD_LINEAR;
      else if( !Q_stricmp( token, "point" ) )
        bp->accMoveValues.dirType = PMD_POINT;

      continue;
    }
    else if( !Q_stricmp( token, "accelerationMagnitude" ) )
    {
      token = COM_Parse( text_p );
      if( !token )
        break;
      
      CG_ParseValueAndVariance( token, &number, &randFrac, qfalse );

      bp->accMoveValues.mag = number;
      bp->accMoveValues.magRandFrac = randFrac;

      continue;
    }
    else if( !Q_stricmp( token, "acceleration" ) )
    {
      for( i = 0; i <= 2; i++ )
      {
        token = COM_Parse( text_p );
        if( !token )
          break;
        
        bp->accMoveValues.dir[ i ] = atof_neg( token, qtrue );
      }
      
      token = COM_Parse( text_p );
      if( !token )
        break;
      
      CG_ParseValueAndVariance( token, NULL, &randFrac, qfalse );

      bp->accMoveValues.dirRandAngle = randFrac;
      
      continue;
    }
    else if( !Q_stricmp( token, "accelerationPoint" ) )
    {
      for( i = 0; i <= 2; i++ )
      {
        token = COM_Parse( text_p );
        if( !token )
          break;
        
        bp->accMoveValues.point[ i ] = atof_neg( token, qtrue );
      }
      
      token = COM_Parse( text_p );
      if( !token )
        break;
      
      CG_ParseValueAndVariance( token, NULL, &randFrac, qfalse );

      bp->accMoveValues.pointRandAngle = randFrac;
      
      continue;
    }
    ///
    else if( !Q_stricmp( token, "displacement" ) )
    {
      for( i = 0; i <= 2; i++ )
      {
        token = COM_Parse( text_p );
        if( !token )
          break;
        
        bp->displacement[ i ] = atof_neg( token, qtrue );
      }
      
      token = COM_Parse( text_p );
      if( !token )
        break;

      CG_ParseValueAndVariance( token, NULL, &randFrac, qfalse );

      bp->randDisplacement = randFrac;

      continue;
    }
    else if( !Q_stricmp( token, "normalDisplacement" ) )
    {
      token = COM_Parse( text_p );
      if( !token )
        break;
      
      bp->normalDisplacement = atof_neg( token, qtrue );

      continue;
    }
    else if( !Q_stricmp( token, "overdrawProtection" ) )
    {
      bp->overdrawProtection = qtrue;

      continue;
    }
    else if( !Q_stricmp( token, "realLight" ) )
    {
      bp->realLight = qtrue;

      continue;
    }
    else if( !Q_stricmp( token, "cullOnStartSolid" ) )
    {
      bp->cullOnStartSolid = qtrue;

      continue;
    }
    else if( !Q_stricmp( token, "radius" ) )
    {
      token = COM_Parse( text_p );
      if( !token )
        break;

      CG_ParseValueAndVariance( token, &number, &randFrac, qfalse );

      bp->radius.delay = (int)number;
      bp->radius.delayRandFrac = randFrac;

      token = COM_Parse( text_p );
      if( !token )
        break;

      CG_ParseValueAndVariance( token, &number, &randFrac, qfalse );

      bp->radius.initial = number;
      bp->radius.initialRandFrac = randFrac;

      token = COM_Parse( text_p );
      if( !token )
        break;

      if( !Q_stricmp( token, "-" ) )
      {
        bp->radius.final = PARTICLES_SAME_AS_INITIAL;
        bp->radius.finalRandFrac = 0.0f;
      }
      else
      {
        CG_ParseValueAndVariance( token, &number, &randFrac, qfalse );

        bp->radius.final = number;
        bp->radius.finalRandFrac = randFrac;
      }

      continue;
    }
    else if( !Q_stricmp( token, "alpha" ) )
    {
      token = COM_Parse( text_p );
      if( !token )
        break;

      CG_ParseValueAndVariance( token, &number, &randFrac, qfalse );

      bp->alpha.delay = (int)number;
      bp->alpha.delayRandFrac = randFrac;

      token = COM_Parse( text_p );
      if( !token )
        break;

      CG_ParseValueAndVariance( token, &number, &randFrac, qfalse );

      bp->alpha.initial = number;
      bp->alpha.initialRandFrac = randFrac;

      token = COM_Parse( text_p );
      if( !token )
        break;

      if( !Q_stricmp( token, "-" ) )
      {
        bp->alpha.final = PARTICLES_SAME_AS_INITIAL;
        bp->alpha.finalRandFrac = 0.0f;
      }
      else
      {
        CG_ParseValueAndVariance( token, &number, &randFrac, qfalse );

        bp->alpha.final = number;
        bp->alpha.finalRandFrac = randFrac;
      }

      continue;
    }
    else if( !Q_stricmp( token, "rotation" ) )
    {
      token = COM_Parse( text_p );
      if( !token )
        break;

      CG_ParseValueAndVariance( token, &number, &randFrac, qfalse );

      bp->rotation.delay = (int)number;
      bp->rotation.delayRandFrac = randFrac;

      token = COM_Parse( text_p );
      if( !token )
        break;

      CG_ParseValueAndVariance( token, &number, &randFrac, qtrue );

      bp->rotation.initial = number;
      bp->rotation.initialRandFrac = randFrac;

      token = COM_Parse( text_p );
      if( !token )
        break;

      if( !Q_stricmp( token, "-" ) )
      {
        bp->rotation.final = PARTICLES_SAME_AS_INITIAL;
        bp->rotation.finalRandFrac = 0.0f;
      }
      else
      {
        CG_ParseValueAndVariance( token, &number, &randFrac, qtrue );

        bp->rotation.final = number;
        bp->rotation.finalRandFrac = randFrac;
      }

      continue;
    }
    else if( !Q_stricmp( token, "lifeTime" ) )
    {
      token = COM_Parse( text_p );
      if( !token )
        break;

      CG_ParseValueAndVariance( token, &number, &randFrac, qfalse );

      bp->lifeTime = (int)number;
      bp->lifeTimeRandFrac = randFrac;

      continue;
    }
    else if( !Q_stricmp( token, "}" ) )
      return qtrue; //reached the end of this particle
    else
    {
      CG_Printf( S_COLOR_RED "ERROR: unknown token '%s' in particle\n", token );
      return qfalse;
    }
  }

  return qfalse;
}


/*
===============
CG_ParseParticleEjector

Parse a particle ejector section
===============
*/
static qboolean CG_ParseParticleEjector( baseParticleEjector_t *bpe, char **text_p )
{
  char  *token;
  float number, randFrac;

  // read optional parameters
  while( 1 )
  {
    token = COM_Parse( text_p );
    
    if( !token )
      break;

    if( !Q_stricmp( token, "" ) )
      return qfalse;

    if( !Q_stricmp( token, "{" ) )
    {
      if( !CG_ParseParticle( &baseParticles[ numBaseParticles ], text_p ) )
      {
        CG_Printf( S_COLOR_RED "ERROR: failed to parse particle\n" );
        return qfalse;
      }

      if( bpe->numParticles == MAX_PARTICLES_PER_EJECTOR )
      {
        CG_Printf( S_COLOR_RED "ERROR: ejector has > %d particles\n", MAX_PARTICLES_PER_EJECTOR );
        return qfalse;
      }
      else if( numBaseParticles == MAX_BASEPARTICLES )
      {
        CG_Printf( S_COLOR_RED "ERROR: maximum number of particles (%d) reached\n", MAX_BASEPARTICLES );
        return qfalse;
      }
      else
      {
        //start parsing particles again
        bpe->particles[ bpe->numParticles ] = &baseParticles[ numBaseParticles ];
        bpe->numParticles++;
        numBaseParticles++;
      }
      continue;
    }
    else if( !Q_stricmp( token, "delay" ) )
    {
      token = COM_Parse( text_p );
      if( !token )
        break;

      CG_ParseValueAndVariance( token, &number, &randFrac, qfalse );

      bpe->eject.delay = (int)number;
      bpe->eject.delayRandFrac = randFrac;

      continue;
    }
    else if( !Q_stricmp( token, "period" ) )
    {
      token = COM_Parse( text_p );
      if( !token )
        break;

      bpe->eject.initial = atoi_neg( token, qfalse );
      
      token = COM_Parse( text_p );
      if( !token )
        break;

      if( !Q_stricmp( token, "-" ) )
        bpe->eject.final = PARTICLES_SAME_AS_INITIAL;
      else
        bpe->eject.final = atoi_neg( token, qfalse );
      
      token = COM_Parse( text_p );
      if( !token )
        break;

      CG_ParseValueAndVariance( token, NULL, &bpe->eject.randFrac, qfalse );

      continue;
    }
    else if( !Q_stricmp( token, "count" ) )
    {
      token = COM_Parse( text_p );
      if( !token )
        break;

      if( !Q_stricmp( token, "infinite" ) )
      {
        bpe->totalParticles = PARTICLES_INFINITE;
        bpe->totalParticlesRandFrac = 0.0f;
      }
      else
      {
        CG_ParseValueAndVariance( token, &number, &randFrac, qfalse );

        bpe->totalParticles = (int)number;
        bpe->totalParticlesRandFrac = randFrac;
      }

      continue;
    }
    else if( !Q_stricmp( token, "particle" ) ) //acceptable text
      continue;
    else if( !Q_stricmp( token, "}" ) )
      return qtrue; //reached the end of this particle ejector
    else
    {
      CG_Printf( S_COLOR_RED "ERROR: unknown token '%s' in particle ejector\n", token );
      return qfalse;
    }
  }

  return qfalse;
}


/*
===============
CG_ParseParticleSystem

Parse a particle system section
===============
*/
static qboolean CG_ParseParticleSystem( baseParticleSystem_t *bps, char **text_p )
{
  char                  *token;
  int                   i;
  baseParticleEjector_t *bpe;

  // read optional parameters
  while( 1 )
  {
    token = COM_Parse( text_p );
    
    if( !token )
      break;

    if( !Q_stricmp( token, "" ) )
      return qfalse;

    if( !Q_stricmp( token, "{" ) )
    {
      if( !CG_ParseParticleEjector( &baseParticleEjectors[ numBaseParticleEjectors ], text_p ) )
      {
        CG_Printf( S_COLOR_RED "ERROR: failed to parse particle ejector\n" );
        return qfalse;
      }

      bpe = &baseParticleEjectors[ numBaseParticleEjectors ];
      
      //check for infinite count + zero period
      if( bpe->totalParticles == PARTICLES_INFINITE &&
          ( bpe->eject.initial == 0.0f || bpe->eject.final == 0.0f ) )
      {
        CG_Printf( S_COLOR_RED "ERROR: ejector with 'count infinite' potentially has zero period\n" );
        return qfalse;
      }

      if( bps->numEjectors == MAX_EJECTORS_PER_SYSTEM )
      {
        CG_Printf( S_COLOR_RED "ERROR: particle system has > %d ejectors\n", MAX_EJECTORS_PER_SYSTEM );
        return qfalse;
      }
      else if( numBaseParticleEjectors == MAX_BASEPARTICLE_EJECTORS )
      {
        CG_Printf( S_COLOR_RED "ERROR: maximum number of particle ejectors (%d) reached\n", MAX_BASEPARTICLE_EJECTORS );
        return qfalse;
      }
      else
      {
        //start parsing ejectors again
        bps->ejectors[ bps->numEjectors ] = &baseParticleEjectors[ numBaseParticleEjectors ];
        bps->numEjectors++;
        numBaseParticleEjectors++;
      }
      continue;
    }
    else if( !Q_stricmp( token, "ejector" ) ) //acceptable text
      continue;
    else if( !Q_stricmp( token, "}" ) )
      return qtrue; //reached the end of this particle system
    else
    {
      CG_Printf( S_COLOR_RED "ERROR: unknown token '%s' in particle system %s\n", token, bps->name );
      return qfalse;
    }
  }

  return qfalse;
}

/*
===============
CG_ParseParticleFile

Load the particle systems from a particle file
===============
*/
static qboolean CG_ParseParticleFile( const char *fileName )
{
  char          *text_p;
  int           i;
  int           len;
  char          *token;
  char          text[ 32000 ];
  char          psName[ MAX_QPATH ];
  qboolean      psNameSet = qfalse;
  fileHandle_t  f;

  // load the file
  len = trap_FS_FOpenFile( fileName, &f, FS_READ );
  if( len <= 0 )
    return qfalse;

  if( len >= sizeof( text ) - 1 )
  {
    CG_Printf( S_COLOR_RED "ERROR: particle file %s too long\n", fileName );
    return qfalse;
  }
  
  trap_FS_Read( text, len, f );
  text[ len ] = 0;
  trap_FS_FCloseFile( f );

  // parse the text
  text_p = text;

  // read optional parameters
  while( 1 )
  {
    token = COM_Parse( &text_p );
    
    if( !token )
      break;

    if( !Q_stricmp( token, "" ) )
      return qfalse;

    if( !Q_stricmp( token, "{" ) )
    {
      if( psNameSet )
      {
        //check for name space clashes
        for( i = 0; i < numBaseParticleSystems; i++ )
        {
          if( !Q_stricmp( baseParticleSystems[ i ].name, psName ) )
          {
            CG_Printf( S_COLOR_RED "ERROR: a particle system is already named %s\n", psName );
            return qfalse;
          }
        }
        
        Q_strncpyz( baseParticleSystems[ numBaseParticleSystems ].name, psName, MAX_QPATH );
        
        if( !CG_ParseParticleSystem( &baseParticleSystems[ numBaseParticleSystems ], &text_p ) )
        {
          CG_Printf( S_COLOR_RED "ERROR: %s: failed to parse particle system %s\n", fileName, psName );
          return qfalse;
        }

        //start parsing particle systems again
        psNameSet = qfalse;
      
        if( numBaseParticleSystems == MAX_BASEPARTICLE_SYSTEMS )
        {
          CG_Printf( S_COLOR_RED "ERROR: maximum number of particle systems (%d) reached\n", MAX_BASEPARTICLE_EJECTORS );
          return qfalse;
        }
        else
          numBaseParticleSystems++;
        
        continue;
      }
      else
      {
        CG_Printf( S_COLOR_RED "ERROR: unamed particle system\n" );
        return qfalse;
      }
    }

    if( !psNameSet )
    {
      Q_strncpyz( psName, token, sizeof( psName ) );
      psNameSet = qtrue;
    }
    else
    {
      CG_Printf( S_COLOR_RED "ERROR: particle system already named\n" );
      return qfalse;
    }
  }

  return qtrue;
}


/*
===============
CG_LoadParticleSystems

Load particle systems from .particle files
===============
*/
void CG_LoadParticleSystems( void )
{
  int         i;
  const char  *s[ MAX_PARTICLE_FILES ];

  numBaseParticleSystems = 0;
  numBaseParticleEjectors = 0;
  numBaseParticles = 0;

  for( i = 0; i < MAX_PARTICLE_FILES; i++ )
  {
    s[ i ] = CG_ConfigString( CS_PARTICLE_FILES + i );
  
    if( strlen( s[ i ] ) > 0 )
    {
      CG_Printf( "...loading '%s'\n", s[ i ] );
      CG_ParseParticleFile( s[ i ] );
    }
    else
      break;
  }
}


/*
===============
CG_AttachParticleSystemToCent

Attach a particle system to a centity_t
===============
*/
void CG_AttachParticleSystemToCent( particleSystem_t *ps )
{
  if( ps == NULL || !ps->valid )
  {
    CG_Printf( S_COLOR_YELLOW "WARNING: tried to modify a NULL particle system\n" );
    return;
  }
  
  ps->attachType = PSA_CENT_ORIGIN;
  ps->attached = qtrue;
}

/*
===============
CG_SetParticleSystemCent

Set a particle system attachment means
===============
*/
void CG_SetParticleSystemCent( particleSystem_t *ps, centity_t *cent )
{
  if( ps == NULL || !ps->valid )
  {
    CG_Printf( S_COLOR_YELLOW "WARNING: tried to modify a NULL particle system\n" );
    return;
  }
  
  ps->attachment.centValid = qtrue;
  ps->attachment.centNum = cent->currentState.number;
}

/*
===============
CG_AttachParticleSystemToTag

Attach a particle system to a model tag
===============
*/
void CG_AttachParticleSystemToTag( particleSystem_t *ps )
{
  if( ps == NULL || !ps->valid )
  {
    CG_Printf( S_COLOR_YELLOW "WARNING: tried to modify a NULL particle system\n" );
    return;
  }
  
  ps->attachType = PSA_TAG;
  ps->attached = qtrue;
}

/*
===============
CG_SetParticleSystemToTag

Set a particle system attachment means
===============
*/
void CG_SetParticleSystemTag( particleSystem_t *ps, refEntity_t parent,
                              qhandle_t model, char *tagName )
{
  if( ps == NULL || !ps->valid )
  {
    CG_Printf( S_COLOR_YELLOW "WARNING: tried to modify a NULL particle system\n" );
    return;
  }
  
  ps->attachment.tagValid = qtrue;
  ps->attachment.parent = parent;
  ps->attachment.model = model;
  strncpy( ps->attachment.tagName, tagName, MAX_STRING_CHARS );
}

/*
===============
CG_AttachParticleSystemToOrigin

Attach a particle system to a point in space
===============
*/
void CG_AttachParticleSystemToOrigin( particleSystem_t *ps )
{
  if( ps == NULL || !ps->valid )
  {
    CG_Printf( S_COLOR_YELLOW "WARNING: tried to modify a NULL particle system\n" );
    return;
  }
  
  ps->attachType = PSA_STATIC;
  ps->attached = qtrue;
}

/*
===============
CG_SetParticleSystemOrigin

Set a particle system attachment means
===============
*/
void CG_SetParticleSystemOrigin( particleSystem_t *ps, vec3_t origin )
{
  if( ps == NULL || !ps->valid )
  {
    CG_Printf( S_COLOR_YELLOW "WARNING: tried to modify a NULL particle system\n" );
    return;
  }
  
  ps->attachment.staticValid = qtrue;
  VectorCopy( origin, ps->attachment.origin );
}

/*
===============
CG_SetParticleSystemNormal

Set a particle system attachment means
===============
*/
void CG_SetParticleSystemNormal( particleSystem_t *ps, vec3_t normal )
{
  if( ps == NULL || !ps->valid )
  {
    CG_Printf( S_COLOR_YELLOW "WARNING: tried to modify a NULL particle system\n" );
    return;
  }
  
  ps->attachment.normalValid = qtrue;
  VectorCopy( normal, ps->attachment.normal );
}


/*
===============
CG_DestroyParticleSystem

Destroy a particle system

This doesn't actually invalidate anything, it just stops
particle ejectors from producing new particles so the 
garbage collector will eventually remove this system.
However is does set the pointer to NULL so the user is
unable to manipulate this particle system any longer.
===============
*/
void CG_DestroyParticleSystem( particleSystem_t **ps )
{
  int               i;
  particleEjector_t *pe;
  
  if( *ps == NULL || !(*ps)->valid )
  {
    CG_Printf( S_COLOR_YELLOW "WARNING: tried to destroy a NULL particle system\n" );
    return;
  }
  
  if( cg_debugParticles.integer >= 1 )
    CG_Printf( "PS destroyed\n" );

  for( i = 0; i < MAX_PARTICLE_EJECTORS; i++ )
  {
    pe = &particleEjectors[ i ];
    
    if( pe->valid && pe->parent == *ps )
      pe->totalParticles = pe->count = 0;
  }

  *ps = NULL;
}

/*
===============
CG_IsParticleSystemInfinite

Test a particle system for 'count infinite' ejectors
===============
*/
qboolean CG_IsParticleSystemInfinite( particleSystem_t *ps )
{
  int               i;
  particleEjector_t *pe;

  if( ps == NULL )
  {
    CG_Printf( S_COLOR_YELLOW "WARNING: tried to test a NULL particle system\n" );
    return qfalse;
  }
  
  if( !ps->valid )
  {
    CG_Printf( S_COLOR_YELLOW "WARNING: tried to test an invalid particle system\n" );
    return qfalse;
  }
  
  //don't bother checking already invalid systems
  if( !ps->valid )
    return qfalse;
  
  for( i = 0; i < MAX_PARTICLE_EJECTORS; i++ )
  {
    pe = &particleEjectors[ i ];
    
    if( pe->valid && pe->parent == ps )
    {
      if( pe->totalParticles == PARTICLES_INFINITE )
        return qtrue;
    }
  }

  return qfalse;
}

/*
===============
CG_IsParticleSystemValid

Test a particle system for validity
===============
*/
qboolean CG_IsParticleSystemValid( particleSystem_t **ps )
{
  if( *ps == NULL || ( *ps && !(*ps)->valid ) )
  {
    if( *ps && !(*ps)->valid )
      *ps = NULL;

    return qfalse;
  }

  return qtrue;
}

/*
===============
CG_GarbageCollectParticleSystems

Destroy inactive particle systems
===============
*/
static void CG_GarbageCollectParticleSystems( void )
{
  int               i, j, count;
  particleSystem_t  *ps;
  particleEjector_t *pe;

  for( i = 0; i < MAX_PARTICLE_SYSTEMS; i++ )
  {
    ps = &particleSystems[ i ];
    count = 0;
    
    //don't bother checking already invalid systems
    if( !ps->valid )
      continue;
    
    for( j = 0; j < MAX_PARTICLE_EJECTORS; j++ )
    {
      pe = &particleEjectors[ j ];
      
      if( pe->valid && pe->parent == ps )
        count++;
    }

    if( !count )
      ps->valid = qfalse;

    //check systems where the parent cent has left the PVS
    //( local player entity is always valid )
    if( ps->attachment.centValid && ps->attachment.centNum != cg.clientNum )
    {
      if( !cg_entities[ ps->attachment.centNum ].valid )
        ps->lazyRemove = qtrue;
    }

    if( cg_debugParticles.integer >= 1 && !ps->valid )
      CG_Printf( "PS %s garbage collected\n", ps->class->name );
  }
}


/*
===============
CG_CalculateTimeFrac

Calculate the fraction of time passed
===============
*/
static float CG_CalculateTimeFrac( int birth, int life, int delay )
{
  float frac;

  frac = ( (float)cg.time - (float)( birth + delay ) ) / (float)( life - delay );

  if( frac < 0.0f )
    frac = 0.0f;
  else if( frac > 1.0f )
    frac = 1.0f;

  return frac;
}

/*
===============
CG_EvaluateParticlePhysics

Compute the physics on a specific particle
===============
*/
static void CG_EvaluateParticlePhysics( particle_t *p )
{
  particleSystem_t  *ps = p->parent->parent;
  baseParticle_t    *bp = p->class;
  vec3_t            acceleration, forward, newOrigin;
  vec3_t            mins, maxs;
  float             deltaTime, bounce, radius, dot;
  trace_t           trace;
  centity_t         *cent;
  
  switch( bp->accMoveType )
  {
    case PMT_STATIC:
      
      if( bp->accMoveValues.dirType == PMD_POINT )
        VectorSubtract( bp->accMoveValues.point, p->origin, acceleration );
      else if( bp->accMoveValues.dirType == PMD_LINEAR )
        VectorCopy( bp->accMoveValues.dir, acceleration );
      
      break;

    case PMT_TAG:
      
      if( !ps->attachment.tagValid )
        return;
      
      if( bp->accMoveValues.dirType == PMD_POINT )
        VectorSubtract( ps->attachment.re.origin, p->origin, acceleration );
      else if( bp->accMoveValues.dirType == PMD_LINEAR )
        VectorCopy( ps->attachment.re.axis[ 0 ], acceleration );
      
      break;

    case PMT_CENT_ANGLES:
      
      if( !ps->attachment.centValid )
        return;
      
      cent = &cg_entities[ ps->attachment.centNum ];
      
      if( bp->accMoveValues.dirType == PMD_POINT )
        VectorSubtract( cent->lerpOrigin, p->origin, acceleration );
      else if( bp->accMoveValues.dirType == PMD_LINEAR )
      {
        AngleVectors( cent->lerpAngles, forward, NULL, NULL );
        VectorCopy( forward, acceleration );
      }
      
      break;
    
    case PMT_NORMAL:
      
      if( !ps->attachment.normalValid )
        return;
      
      VectorCopy( ps->attachment.normal, acceleration );
      
      break;
  }

#define MAX_ACC_RADIUS 1000.0f
  
  if( bp->accMoveValues.dirType == PMD_POINT )
  {
    //FIXME: so this fall off is a bit... odd -- it works..
    float r2 = DotProduct( acceleration, acceleration ); // = radius^2
    float scale = ( MAX_ACC_RADIUS - r2 ) / MAX_ACC_RADIUS;

    if( scale > 1.0f )
      scale = 1.0f;
    else if( scale < 0.1f )
      scale = 0.1f;
    
    scale *= CG_RandomiseValue( bp->accMoveValues.mag, bp->accMoveValues.magRandFrac );
    
    VectorNormalize( acceleration );
    CG_SpreadVector( acceleration, bp->accMoveValues.dirRandAngle );
    VectorScale( acceleration, scale, acceleration );
  }
  else if( bp->accMoveValues.dirType == PMD_LINEAR )
  {
    VectorNormalize( acceleration );
    CG_SpreadVector( acceleration, bp->accMoveValues.dirRandAngle );
    VectorScale( acceleration,
                 CG_RandomiseValue( bp->accMoveValues.mag, bp->accMoveValues.magRandFrac ),
                 acceleration );
  }
  
  radius = CG_LerpValues( p->radius.initial,
                 p->radius.final,
                 CG_CalculateTimeFrac( p->birthTime,
                                       p->lifeTime,
                                       p->radius.delay ) );
  
  VectorSet( mins, -radius, -radius, -radius );
  VectorSet( maxs, radius, radius, radius );

  bounce = CG_RandomiseValue( bp->bounceFrac, bp->bounceFracRandFrac );

  deltaTime = (float)( cg.time - p->lastEvalTime ) * 0.001;
  VectorMA( p->velocity, deltaTime, acceleration, p->velocity );
  VectorMA( p->origin, deltaTime, p->velocity, newOrigin );
  p->lastEvalTime = cg.time;
  
  CG_Trace( &trace, p->origin, mins, maxs, newOrigin, -1, CONTENTS_SOLID );
  
  //not hit anything or not a collider
  if( trace.fraction == 1.0f || bounce == 0.0f )
  {
    VectorCopy( newOrigin, p->origin );
    return;
  }
  
  //remove particles that get into a CONTENTS_NODROP brush
  if( ( trap_CM_PointContents( trace.endpos, 0 ) & CONTENTS_NODROP ) ||
      ( bp->cullOnStartSolid && trace.startsolid ) || bp->bounceCull )
  {
    p->valid = qfalse;
    return;
  }

  //reflect the velocity on the trace plane
  dot = DotProduct( p->velocity, trace.plane.normal );
  VectorMA( p->velocity, -2.0f * dot, trace.plane.normal, p->velocity );

  VectorScale( p->velocity, bounce, p->velocity );

  VectorCopy( trace.endpos, p->origin );
}


#define GETKEY(x,y) (((x)>>y)&0xFF)

/*
===============
CG_Radix
===============
*/
static void CG_Radix( int bits, int size, particle_t *source, particle_t *dest )
{
  int count[ 256 ];
  int index[ 256 ];
  int i;
  
  memset( count, 0, sizeof( count ) );
  
  for( i = 0; i < size; i++ )
    count[ GETKEY( source[ i ].sortKey, bits ) ]++;

  index[ 0 ] = 0;
  
  for( i = 1; i < 256; i++ )
    index[ i ] = index[ i - 1 ] + count[ i - 1 ];
  
  for( i = 0; i < size; i++ )
    dest[ index[ GETKEY( source[ i ].sortKey, bits ) ]++ ] = source[ i ];
}

/*
===============
CG_RadixSort

Radix sort with 4 byte size buckets
===============
*/
static void CG_RadixSort( particle_t *source, particle_t *temp, int size )
{
  CG_Radix( 0,   size, source, temp );
  CG_Radix( 8,   size, temp, source );
  CG_Radix( 16,  size, source, temp );
  CG_Radix( 24,  size, temp, source );
}

/*
===============
CG_CompactAndSortParticles

Depth sort the particles
===============
*/
static void CG_CompactAndSortParticles( void )
{
  int     i, j = 0;
  int     numParticles;
  vec3_t  delta;

  for( i = MAX_PARTICLES - 1; i >= 0; i-- )
  {
    if( particles[ i ].valid )
    {
      while( particles[ j ].valid )
        j++;

      //no more holes
      if( j >= i )
        break;

      particles[ j ] = particles[ i ];
      memset( &particles[ i ], 0, sizeof( particles[ 0 ] ) );
    }
  }

  numParticles = i;
  
  //set sort keys
  for( i = 0; i < numParticles; i++ )
  {
    VectorSubtract( particles[ i ].origin, cg.refdef.vieworg, delta );
    particles[ i ].sortKey = (int)DotProduct( delta, delta );
  }
  
  CG_RadixSort( particles, sortParticles, numParticles );
  
  //reverse order of particles array
  for( i = 0; i < numParticles; i++ )
    sortParticles[ i ] = particles[ numParticles - i - 1 ];
  
  for( i = 0; i < numParticles; i++ )
    particles[ i ] = sortParticles[ i ];
}

/*
===============
CG_RenderParticle

Actually render a particle
===============
*/
static void CG_RenderParticle( particle_t *p )
{
  refEntity_t     re;
  float           timeFrac, frac;
  int             index;
  baseParticle_t  *bp = p->class;
  vec3_t          alight, dlight, lightdir;
  int             i;
    
  memset( &re, 0, sizeof( refEntity_t ) );

  for( i = 0; i <= 3; re.shaderRGBA[ i++ ] = 0xFF );

  timeFrac = CG_CalculateTimeFrac( p->birthTime, p->lifeTime, 0 );

  re.reType = RT_SPRITE;
  re.shaderTime = p->birthTime / 1000.0f; //FIXME: allow user to change?

  re.shaderRGBA[ 3 ] = (byte)( (float)0xFF * 
                       CG_LerpValues( p->alpha.initial,
                             p->alpha.final,
                             CG_CalculateTimeFrac( p->birthTime,
                                                   p->lifeTime,
                                                   p->alpha.delay ) ) );
  
  re.radius = CG_LerpValues( p->radius.initial,
                    p->radius.final,
                    CG_CalculateTimeFrac( p->birthTime,
                                          p->lifeTime,
                                          p->radius.delay ) );
  
  re.rotation = CG_LerpValues( p->rotation.initial,
                      p->rotation.final,
                      CG_CalculateTimeFrac( p->birthTime,
                                            p->lifeTime,
                                            p->rotation.delay ) );

  // if the view would be "inside" the sprite, kill the sprite
  // so it doesn't add too much overdraw
  if( Distance( p->origin, cg.refdef.vieworg ) < re.radius && bp->overdrawProtection )
    return;

  //apply environmental lighting to the particle
  if( bp->realLight )
  {
    trap_R_LightForPoint( p->origin, alight, dlight, lightdir );
    for( i = 0; i <= 2; i++ )
      re.shaderRGBA[ i ] = (int)alight[ i ];
  }

  if( bp->framerate == 0.0f )
  {
    //sync animation time to lifeTime of particle
    index = (int)( timeFrac * ( bp->numFrames + 1 ) );

    if( index >= bp->numFrames )
      index = bp->numFrames - 1;

    re.customShader = bp->shaders[ index ];
  }
  else
  {
    //looping animation
    index = (int)( bp->framerate * timeFrac * p->lifeTime * 0.001 ) % bp->numFrames;
    re.customShader = bp->shaders[ index ];
  }

  VectorCopy( p->origin, re.origin );

  trap_R_AddRefEntityToScene( &re );
}

/*
===============
CG_AddParticles

Add particles to the scene
===============
*/
void CG_AddParticles( void )
{
  int           i;
  particle_t    *p;
  int           numPS = 0, numPE = 0, numP = 0;
  
  //remove expired particle systems
  CG_GarbageCollectParticleSystems( );
  
  //check each ejector and introduce any new particles
  CG_SpawnNewParticles( );

  //sorting
  if( cg_depthSortParticles.integer )
    CG_CompactAndSortParticles( );

  for( i = 0; i < MAX_PARTICLES; i++ )
  {
    p = &particles[ i ];
    
    if( p->valid )
    {
      if( p->birthTime + p->lifeTime > cg.time )
      {
        //particle is active
        CG_EvaluateParticlePhysics( p );
        CG_RenderParticle( p );
      }
      else
        p->valid = qfalse;
    }
  }

  if( cg_debugParticles.integer >= 2 )
  {
    for( i = 0; i < MAX_PARTICLE_SYSTEMS; i++ )
      if( particleSystems[ i ].valid )
        numPS++;
    
    for( i = 0; i < MAX_PARTICLE_EJECTORS; i++ )
      if( particleEjectors[ i ].valid )
        numPE++;
    
    for( i = 0; i < MAX_PARTICLES; i++ )
      if( particles[ i ].valid )
        numP++;

    CG_Printf( "PS: %d  PE: %d  P: %d\n", numPS, numPE, numP );
  }
}

/*
===============
CG_ParticleSystemEntity

Particle system entity client code
===============
*/
void CG_ParticleSystemEntity( centity_t *cent )
{
  entityState_t *es;

  es = &cent->currentState;
  
  if( es->eFlags & EF_NODRAW )
  {
    if( CG_IsParticleSystemValid( &cent->entityPS ) && CG_IsParticleSystemInfinite( cent->entityPS ) )
      CG_DestroyParticleSystem( &cent->entityPS );

    return;
  }
  
  if( !CG_IsParticleSystemValid( &cent->entityPS ) && !cent->entityPSMissing )
  {
    cent->entityPS = CG_SpawnNewParticleSystem( cgs.gameParticleSystems[ es->modelindex ] );

    if( CG_IsParticleSystemValid( &cent->entityPS ) )
    {
      CG_SetParticleSystemOrigin( cent->entityPS, cent->lerpOrigin );
      CG_SetParticleSystemCent( cent->entityPS, cent );
      CG_AttachParticleSystemToOrigin( cent->entityPS );
    }
    else
      cent->entityPSMissing = qtrue;
  }
}