C++, modification of (random) object in a queue not desired, object pointors

I've created a queue (thanks to vector library) of object pointors.

std::vector<Polygon*>queue;

My class Polygon is the mother class of all the others, basicaly the aim of it is to draw a shape. So the polygon is drawing a polygon, the rectangle a rectangle... with both * and # chosen at random. It actually perfectly works.

So I wanted to create several of these drawings and put them in a queue and when the program ends display all the shapes (using a FIFO). At first it seems to works, but diging a bit I realized that the drawing where different.

For example the rectangle will still be a rectangle, with the same dimension, but the patern of * and # will be different. So it means that the figure has not been saved, but its parameters have been. And the queue is rebuilding those.

What I would like to do is to save the same shape, what did I do wrong ?

/* 
 * File:   main.cpp
 * Author: vfortineau
 *
 * Created on may 12nd 2015, 10:25
 */

#include <cstdlib>
#include <iostream>
#include <vector>
#include "Polygon.h"
#include "Rectangle.h"
#include "Square.h"
#include "IsoscelesTriangle.h"
#include "ReversedTriangle.h"
#include "Diamond.h"

using namespace std;

/*
 * 
 */
int main(int argc, char** argv) {
    int choice;
    int _height;
    int _width;
    int _posi;
    int i=0;
    Polygon* polymorph;
    std::vector<Polygon*>queue;
    while (1)
    {

        cout << "\n\tPlease type one of the following command :\n" << endl;
        cout << "\t********************************************\n"<<\
                "\t* 1 - Upright isosceles triangle           *\n" << \
                "\t* 2 - Inverted isosceles triangle          *\n" << \
                "\t* 3 - Rectangle                            *\n" << \
                "\t* 4 - Square                               *\n"<< \
                "\t* 5 - Diamond                              *\n"<< \
                "\t* 6 - Polygone                             *\n" << \
                "\t* 0 - Exit Program                         *\n" << \
                "\t********************************************" << endl;
        cin >> choice;
        switch(choice)
        {
            case 1:
                cout << "Choose the size of the height (please type an integer) : \n";
                cin >> _height;
                cout << "Choose the position (please type an integer) : \n ";
                cin >> _posi;
                polymorph = new IsoscelesTriangle(_height, _posi);
                polymorph->drawShape();
                queue.push_back(polymorph); 

                break;
            case 2:
                cout << "Choose the size of the height (please type an integer) : \n";
                cin >> _height;
                cout << "Choose the position (please type an integer) : \n ";
                cin >> _posi;
                polymorph = new ReversedTriangle(_height, _posi);
                polymorph->drawShape();
                queue.push_back(polymorph); 
                break;
            case 3:
                cout << "Choose the size of the height (please type an integer) : \n";
                cin >> _height;
                cout << "Choose the size of the width (please type an integer) : \n";
                cin >> _width;
                cout << "Choose the position (please type an integer) : \n ";
                cin >> _posi; 
                polymorph = new Rectangle(_height, _width, _posi);
                polymorph->drawShape();
                queue.push_back(polymorph); 
                break;
            case 4:
                cout << "Choose the size of the sides (please type an integer) : \n";
                cin >> _height;
                cout << "Choose the position (please type an integer) : \n ";
                cin >> _posi; 
                polymorph = new Square(_height, _width, _posi);
                polymorph->drawShape(); 
                queue.push_back(polymorph); 
                break;
            case 5:
                cout << "Choose the size of the vertical diagonal (please type an integer) : \n";
                cin >> _height;
                cout << "Choose the position (please type an integer) : \n ";
                cin >> _posi; 
                polymorph = new Diamond(_height, _posi);
                polymorph->drawShape();
                queue.push_back(polymorph); 
                break;
            case 6:
                cout << "Choose the size of the height (please type an integer) : \n";
                cin >> _height;
                cout << "Choose the size of the width (please type an integer) : \n";
                cin >> _width;
                cout << "Choose the position (please type an integer) : \n ";
                cin >> _posi; 
                polymorph = new Polygon(_height, _width, _posi);
                polymorph->drawShape(); 
                queue.push_back(polymorph); 
                break;
            case 0:
                while(not queue.empty())
                {
                    i++;
                    cout << endl << "\t Figure " << i << endl;
                    cout << "\t---------\n\n";
                    queue[0]->drawShape();
                    queue.erase(queue.begin());                    
                }
                return 0;
        }
    }
    return 0;
}

I'm joining as an example a version of a drawShape() function but I don't think the problem is coming from here.

void IsoscelesTriangle::drawShape()
{
    srand(time(NULL));
    int random=0;
    for(int i=0; i<height; i++)
    {
        position();
        for(int j=0; j<height-(i+1); j++)
        {
            std::cout << "  ";
        }
        for (int k=0; k<(2*i+1); k++)
        {
            random=rand()%2;
            if (random==0) std::cout << "* ";
            else std::cout << "# ";            
        }
        std::cout << std::endl;
    }
}

height is a protected member of Polygon, and position a public function of Polygon.

An example of output