explosion.cpp

“恐怖之战”游戏源码

#include "explosion.h"


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);
} 

// 设置初始粒子的属性
void CExplosion::InitializeParticle(int index)
{
	// 在发射区域的随机位置开始粒子运动
	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;
	// 设置粒子的大小
	m_particleList[index].m_size = PARTICLE_SIZE + FRAND * SIZE_VARIATION;
	// 给定粒子一个随机速度
	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] = 0.5 + FRAND * 0.5;
	m_particleList[index].m_color[2] = 0.0;
	m_particleList[index].m_color[3] = 1.0;
	m_particleList[index].m_energy = 1.5 + FRAND/2.0;
	m_particleList[index].m_colorDelta[0] = 0.0;
	m_particleList[index].m_colorDelta[1] = -(m_particleList[index].m_color[1]/2.0)/m_particleList[index].m_energy;
	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;
} 

// 更新存在的粒子，消灭死亡的粒子和创建新的粒子
void CExplosion::Update(float elapsedTime)
{
	for (int i = 0; i < m_numParticles; )
	{
		// 根据速度和时间，更新粒子的位置
		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;
		// 如果粒子碰到地面，则该粒子死亡
		if (m_particleList[i].m_energy <= 0.0)
		{
			// 将最后的粒子运动到当前的位置，并减少数量
			m_particleList[i] = m_particleList[--m_numParticles];
		}
		else
		{
			++i;
		}
	}
} 

// 绘制粒子
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);
	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);
	glEnable(GL_DEPTH_TEST);
}