www.pudn.com > ATimeToKill.rar > explosion.cpp

/**************************************************************************** 
 Particles.h  Particle and particle system base classes. 
  
 Author   :   Dave Astle 
 Date     :   2/1/2001 
 
 Written for OpenGL Game Programming 
*****************************************************************************/ 
 
 
/********************************* Includes *********************************/ 
#include "explosion.h" 
 
 
/***************************************************************************** 
 CExplosion::Constructor 
 
 Nothing to do 
*****************************************************************************/ 
CExplosion::CExplosion(int numParticles, CVector origin, float spread, GLuint texture) 
  : m_texture(texture), m_spread(spread), CParticleSystem(numParticles, origin) 
{ 
  srand(timeGetTime()); 
  CParticleSystem::InitializeSystem(); 
  Emit(numParticles); 
} // end CExplosion::Constructor 
 
 
/***************************************************************************** 
 CExplosion::InitializeParticle() 
 
 Sets the initial particle properties for the explosion 
*****************************************************************************/ 
void CExplosion::InitializeParticle(int index) 
{ 
  // start the particle at the sky at a random location in the emission zone 
  m_particleList[index].m_pos.x = m_origin.x + FRAND * m_spread; 
  m_particleList[index].m_pos.y = m_origin.y + FRAND * m_spread; 
  m_particleList[index].m_pos.z = m_origin.z + FRAND * m_spread; 
 
  // set the size of the particle 
  m_particleList[index].m_size = PARTICLE_SIZE + FRAND * SIZE_VARIATION; 
 
  // give the particle a random velocity 
  m_particleList[index].m_velocity.x = PARTICLE_VELOCITY.x + FRAND * VELOCITY_VARIATION.x; 
  m_particleList[index].m_velocity.y = PARTICLE_VELOCITY.y + FRAND * VELOCITY_VARIATION.y; 
  m_particleList[index].m_velocity.z = PARTICLE_VELOCITY.z + FRAND * VELOCITY_VARIATION.z; 
 
  m_particleList[index].m_acceleration = PARTICLE_ACCELERATION; 
 
  m_particleList[index].m_color[0] = 1.0; 
  m_particleList[index].m_color[1] = 1.0; 
  m_particleList[index].m_color[2] = 0.4; 
  m_particleList[index].m_color[3] = 1.0; 
 
  m_particleList[index].m_energy = 0.5 + FRAND/2.0; 
 
  m_particleList[index].m_colorDelta[0] = 0.0; 
  m_particleList[index].m_colorDelta[1] = 0.0; 
  m_particleList[index].m_colorDelta[2] = 0.0; 
  m_particleList[index].m_colorDelta[3] = -1.0/m_particleList[index].m_energy; 
 
//  m_particleList[index].m_sizeDelta = -m_particleList[index].m_size/m_particleList[index].m_energy; 
  m_particleList[index].m_sizeDelta = 8.0; 
 
} // end CExplosion::InitializeParticle 
 
 
/***************************************************************************** 
 CExplosion::Update 
 
 Update the existing particles, killing them and creating new ones as needed 
*****************************************************************************/ 
void CExplosion::Update(float elapsedTime) 
{ 
  for (int i = 0; i < m_numParticles; ) 
  { 
    // update the particle's position based on the elapsed time and velocity 
    m_particleList[i].m_pos = m_particleList[i].m_pos + m_particleList[i].m_velocity * elapsedTime; 
    m_particleList[i].m_velocity = m_particleList[i].m_velocity + m_particleList[i].m_acceleration * elapsedTime; 
 
    m_particleList[i].m_energy -= elapsedTime; 
    m_particleList[i].m_size += m_particleList[i].m_sizeDelta * elapsedTime; 
 
    m_particleList[i].m_color[3] += m_particleList[i].m_colorDelta[3] * elapsedTime; 
    m_particleList[i].m_color[1] += m_particleList[i].m_colorDelta[1] * elapsedTime; 
 
    // if the particle has hit the ground plane, kill it 
    if (m_particleList[i].m_energy <= 0.0) 
    { 
      // move the last particle to the current positon, and decrease the count 
      m_particleList[i] = m_particleList[--m_numParticles]; 
    } 
    else 
    { 
      ++i; 
    } 
  } 
} // end CExplosion::Update() 
 
 
/***************************************************************************** 
 CExplosion::Render() 
 
 Draw the snowflake particles as textured quads 
*****************************************************************************/ 
void CExplosion::Render() 
{ 
  float viewMatrix[16]; 
  glGetFloatv(GL_MODELVIEW_MATRIX, viewMatrix); 
 
  CVector right(viewMatrix[0], viewMatrix[4], viewMatrix[8]); 
  CVector up(viewMatrix[1], viewMatrix[5], viewMatrix[9]); 
 
//  glDisable(GL_DEPTH_TEST); 
  glDepthMask(GL_FALSE); 
  glEnable(GL_BLEND); 
  glBlendFunc(GL_SRC_ALPHA, GL_DST_ALPHA); 
 
  glEnable(GL_TEXTURE_2D); 
  glBindTexture(GL_TEXTURE_2D, m_texture); 
  glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE); 
 
  GLfloat size; 
  CVector pos; 
 
  glBegin(GL_QUADS); 
  for (int i = 0; i < m_numParticles; ++i) 
  { 
    size = m_particleList[i].m_size/2; 
    pos = m_particleList[i].m_pos; 
    glColor4fv(m_particleList[i].m_color); 
    glTexCoord2f(0.0, 0.0); glVertex3fv((pos + (right + up) * - size).v); 
    glTexCoord2f(1.0, 0.0); glVertex3fv((pos + (right - up) * size).v); 
    glTexCoord2f(1.0, 1.0); glVertex3fv((pos + (right + up) * size).v); 
    glTexCoord2f(0.0, 1.0); glVertex3fv((pos + (up - right) * size).v); 
  } 
  glEnd(); 
  glDisable(GL_TEXTURE_2D); 
  glDisable(GL_BLEND); 
  glDepthMask(GL_TRUE); 
//  glEnable(GL_DEPTH_TEST); 
} // end CExplosion::Update