particles.cpp

一本关于OPenGL的很好的电子书

/****************************************************************************
 Particles.cpp
 
 Author   :   Dave Astle
 Date     :   2/1/2001

 Written for OpenGL Game Programming
*****************************************************************************/
#include "Particles.h"


/*****************************************************************************
 CParticleSystem::Constructor
 
 Store initialization values and set defaults.
*****************************************************************************/
CParticleSystem::CParticleSystem(int maxParticles, vector3_t origin)
{
  m_maxParticles = maxParticles;
  m_origin = origin;
  m_particleList = NULL;
} // end CParticleSystem::Constructor


/*****************************************************************************
 CParticleSystem::Emit()
 
 Creates the number of new particles specified by the parameter, using
 the general particle system values with some random element. Note that
 only initial values will be randomized. Final values will not. This may
 be changed in the future.
*****************************************************************************/
int CParticleSystem::Emit(int numParticles)
{
  // create numParticles new particles (if there's room)
  while (numParticles && (m_numParticles < m_maxParticles))
  {
    // initialize the current particle and increase the count
    InitializeParticle(m_numParticles++);
    --numParticles;
  }
  return numParticles;
} // end CParticleSystem::Emit


/*****************************************************************************
 CParticleSystem::InitializeSystem()
 
 Allocate memory for the maximum number of particles in the system
*****************************************************************************/
void CParticleSystem::InitializeSystem()
{
  // if this is just a reset, free the memory
  if (m_particleList)
  {
    delete[] m_particleList;
    m_particleList = NULL;
  }

  // allocate the maximum number of particles
  m_particleList = new particle_t[m_maxParticles];

  // reset the number of particles and accumulated time
  m_numParticles = 0;
  m_accumulatedTime = 0.0f;
} // end CParticleSystem::InitializeSystem


/*****************************************************************************
 CParticleSystem::KillSystem()
 
 Tells the emitter to stop emitting. If the parameter is true, all live
 particles are killed as well.  Otherwise, they are allowed to die off on
 their own.
*****************************************************************************/
void CParticleSystem::KillSystem()
{
  if (m_particleList)
  {
    delete[] m_particleList;
    m_particleList = NULL;
  }

  m_numParticles = 0;
} // end CParticleSystem::KillSystem