Thread: OpenGL Particle Engine Demo

Code:

#include <cstdlib>
#include <ctime>
#include "particle.h"
#include <gl/gl.h>
inline float FloatRand(float MaxVal)
{
    return float(rand()%100)/((100/MaxVal)+0.1);
}

ParticleEffect::ParticleEffect(int no, float x, float y, float z, float size,
                               float speedx, float speedy, float speedz, float life,
                               float fade, float r, float g, float b, float a, float perm,
                               bool forever)
{
    srand(time(0));
    particles = new Particle[no];
    for (int i=0;i<no;i++)
    {
        particles[i].x = (x-(0.5*size))+FloatRand(size);
        particles[i].y = (y-(0.5*size))+FloatRand(size);
        particles[i].z = (z-(0.5*size))+FloatRand(size);
        particles[i].life = (life-(0.5*fade))+FloatRand(fade);
        particles[i].r = r;
        particles[i].g = g;
        particles[i].b = b;
        particles[i].a = a;
        particles[i].speedx = (speedx-(0.25*speedx))+FloatRand(0.25*speedx);
        particles[i].speedy = (speedy-(0.25*speedy))+FloatRand(0.25*speedy);
        particles[i].speedz = (speedz-(0.25*speedz))+FloatRand(0.25*speedz);
        particles[i].fade = (fade-(0.15*fade))+FloatRand(fade*0.15);
        particles[i].perimeter = perm;
    }
    count = no;
    endless = forever;
    this->x=x;
    this->y=y;
    this->z=z;
    this->life=life;
    this->fade=fade;
    this->size=size;
    this->r=r;
    this->g=g;
    this->b=b;
    this->a=a;
    this->speedx = speedx;
    this->speedy = speedy;
    this->speedz = speedz;
    this->perimeter = perimeter;
}

void ParticleEffect::Render()
{
    for (int i=0;i<count;i++)
    {
        if (particles[i].life <= 0)
        {
            particles[i].x = (x-(0.5*size))+FloatRand(size);
            particles[i].y = (y-(0.5*size))+FloatRand(size);
            particles[i].z = (z-(0.5*size))+FloatRand(size);
        particles[i].life = (life-(0.5*fade))+FloatRand(fade);
        particles[i].r = r;
        particles[i].g = g;
        particles[i].b = b;
        particles[i].a = a;
        particles[i].speedx = (speedx-(0.5*speedx))+FloatRand(0.5*speedx);
        particles[i].speedy = (speedy-(0.5*speedy))+FloatRand(0.5*speedy);
        particles[i].speedz = (speedz-(0.5*speedz))+FloatRand(0.5*speedz);
        particles[i].fade = (fade-(fade))+FloatRand(fade);
        particles[i].perimeter = perimeter;
        }
        glBegin(GL_QUADS);  
            glColor4f(particles[i].r, particles[i].g, particles[i].b, particles[i].a + (particles[i].life/2));
            glVertex3f(particles[i].x - (particles[i].perimeter*0.5),
                       particles[i].y + (particles[i].perimeter*0.5), particles[i].z);
            glVertex3f(particles[i].x + (particles[i].perimeter*0.5),
                       particles[i].y + (particles[i].perimeter*0.5), particles[i].z);
            glVertex3f(particles[i].x + (particles[i].perimeter*0.5),
                       particles[i].y - (particles[i].perimeter*0.5), particles[i].z);
            glVertex3f(particles[i].x - (particles[i].perimeter*0.5),
                       particles[i].y - (particles[i].perimeter*0.5), particles[i].z);         
        glEnd();
        
        particles[i].life -= particles[i].fade;
        particles[i].x += particles[i].speedx;
        particles[i].y += particles[i].speedy;
        particles[i].z += particles[i].speedz;
    }
}

As you can see, it's a hack. It's extremely ugly. It makes me want to puke just seeing it.