C++/SDL - Particle engine

//This program is made by thecplusplusguy from YouTube for demonstartion purposes.
//Feel free to read, learn, or modifie the source as you wish, LGPL licence, I guess.
//http://www.youtube.com/user/thecplusplusguy
//keep this header comment for advertisment :)
//compile in case of Windows normally, in case of Linux normally as well, so:
//g++ particle.cpp -lSDL
//Code::blocks: build and run
#include <SDL/SDL.h>
#include <iostream>
#include <vector>   //to store the particles (I like std::vector :D)
#include <cstdlib>  //for the random numbers
#include <ctime>

class particle{ //represent 1 particle
    float x,y,xvel,yvel;    //position && speed
    Uint32 endTime; //death time
    Uint8 color;    //color
    public:
    particle(float X,float Y,float Xvel,float Yvel,int life,Uint8 Color);
    void move();
    void show();
    bool isDead();  //true if the particle dead else false
};

particle::particle(float X,float Y,float Xvel,float Yvel,int life,Uint8 Color)
{
    //initialize the variables, nothing new
    x=X;
    y=Y;
    xvel=Xvel;
    yvel=Yvel;
    endTime=SDL_GetTicks()+life; //the end time, is the current time + the time, while the particle lives
    color=Color;
}

void particle::move()
{
    //move
    x+=xvel;
    y+=yvel;
    //if it is outside of the screen, set it back to the edge of the screen
    if(x<0)
        x=0;
    if(y<0)
        y=0;
    if(x>SDL_GetVideoSurface()->w)
        x=SDL_GetVideoSurface()->w-1;
    if(y>SDL_GetVideoSurface()->h)
        y=SDL_GetVideoSurface()->h-1;
}

void particle::show()
{
    //just set the pixel to the current color at the current position (pixel manipulation tutorial)
    Uint8* pixels=(Uint8*)SDL_GetVideoSurface()->pixels;
    Uint8* pixel=pixels+(int)y*SDL_GetVideoSurface()->pitch+(int)x;
    *pixel=color;
}

bool particle::isDead()
{
    //read above, what it does
    return (SDL_GetTicks()>=endTime || x==0 || y==0 || x==SDL_GetVideoSurface()->w-1 || y==SDL_GetVideoSurface()->h-1);
}
//the particle engine will store all of the particle, and their initialize position
class particleEngine{
    std::vector<particle*> particles;   //this vector represent all of the particle
    int x,y,maxparticle;
    public:
    particleEngine(int maxpart,int X, int Y);
    ~particleEngine();  //need for deallocate allocated space
    void refresh(); //move && show the particles
};

particleEngine::particleEngine(int maxpart,int X, int Y)
{
    x=X;
    y=Y;
    maxparticle=maxpart;
    for(int i=0;i<maxparticle;i++)  //create maxparticle number of particles with random values both for position, velocity, life, color
        particles.push_back(new particle(x+rand()%6-3,y+rand()%6-3,rand()%10+(float)rand()/(float)RAND_MAX-5,rand()%10+(float)rand()/(float)RAND_MAX-5,500+rand()%1000,rand()%255));
}

particleEngine::~particleEngine()
{
    //deallocate all reserved memory
    for(int i=0;i<maxparticle;i++)
        delete particles[i];
}

void particleEngine::refresh()
{
    for(int i=0;i<maxparticle;i++)
    {
        if(particles[i]->isDead())  //if dead
        {
            delete particles[i];    //delete the earlier one and create a new
            particles[i]=new particle(x+rand()%6-3,y+rand()%6-3,rand()%10+(float)rand()/(float)RAND_MAX-5,rand()%10+(float)rand()/(float)RAND_MAX-5,500+rand()%2000,rand()%255);
        }else{  //else
            particles[i]->move();   //move && show
            particles[i]->show();
        }
    }
}

int main(int argc,char** argv)
{
    //this should be familiar to you
    SDL_Init(SDL_INIT_EVERYTHING);
    SDL_Surface* screen;
    screen=SDL_SetVideoMode(640,480,8,SDL_SWSURFACE);
    bool running=true;
    const int FPS=30;   //make the FPS bigger, for quicker animation
    Uint32 start;
    srand(time(0)); //seed the random number generator
    particleEngine ps(5000,screen->w/2,screen->h/2);    //create the particles
    while(running)
    {
        start=SDL_GetTicks();
        SDL_Event event;
        while(SDL_PollEvent(&event))
        {
            switch(event.type)
            {
                case SDL_QUIT:
                    running=false;
                    break;
            }
        }

    SDL_FillRect(screen,&screen->clip_rect,SDL_MapRGB(screen->format,0x00,0x00,0x00));  //clear the screen
        //logic
    ps.refresh();   //refresh the particles


    SDL_Flip(screen);
        if(1000/FPS>SDL_GetTicks()-start)
            SDL_Delay(1000/FPS-(SDL_GetTicks()-start));
    }
    SDL_Quit();
    return 0;
}