c++面向对象菱形

我有问题与我已经给出的任务，问题是我找不到任何资源，无论如何类似于我已经给出的代码。我已经通读了那么多的文件，试图找到相似之处，但没有找到任何有用的。

我需要帮助试图理解这段代码，以及如何使用它来创建一个菱形。我唯一不能掌握的是如何创建属于shape类的菱形形状。在菱形上应用一个质心，然后使用push_back方法添加顶点。不幸的是，这个推回方法需要使用，我失败的考试只是使用drawLine(10,10,40,10);在我想要的地方画线。

我要花整整一周的时间来处理这个问题，所以我应该迅速做出回应。

//This is the rhombus.cpp file
#include "rhombus.h"
Rhombus::Rhombus(Vertex point, int radius) : Shape(point)
{
    if((radius>centroid.getX()/2) || (radius>centroid.getY()/2)) // Inteded to be a y?
    {
        cout << "Object must fit on screen." << endl;
        system("pause");
        exit(0);
    }
    Rhombus shape1(20, 20);
    shape1.plotVertices();
}
void Rhombus::plotVertices()
{
    //vertices.push_back(Vertex(centroid.getX(), centroid.getY() + radius));
    //vertices.push_back(Vertex(centroid.getX(), centroid.getY()));
    //vertices.push_back(Vertex(centroid.getX(), centroid.getY()));
    //vertices.push_back(Vertex(centroid.getX(), centroid.getY()));
}

// This is the rhombus.h file
#include "shape.h"
class Rhombus : public Shape 
{
    int radius;
    void plotVertices();
    Rhombus(Vertex point, int radius = 10);
    int area();
    int perimeter();
};

// This is the shape.cpp file
#include "shape.h"
Shape::Shape(Vertex point) : centroid(point)
{
    // constructs a shape
}
void Shape::drawShape()
{
    list<Vertex>::iterator current = vertices.begin();
    list<Vertex>::iterator previous = vertices.begin();
    while(current!=vertices.end())
    {
        Console::gotoXY((*current).getX(),(*current).getY());
        cout << "*";
        if(current!=vertices.begin())
            drawLine((*current).getX(),(*current).getY(), (*previous).getX(),            (*previous).getY());
        previous = current;
        current++;
    }
    previous = vertices.begin();
    //Debug assertion error here.
    drawLine(vertices.back().getX(), vertices.back().getY(), vertices.front().getX(),     vertices.front().getY());
}
void Shape::drawLine(int x1, int y1, int x2, int y2)
{      
    bool steep = (abs(y2 - y1) > abs(x2 - x1));
    if(steep)
    {
        swap(x1, y1);
        swap(x2, y2);
    }
    if(x1 > x2)
    {
        swap(x1, x2);
        swap(y1, y2);
    }
    int dx = x2 - x1;
    int dy = abs(y2 - y1);
    float error = dx / 2.0f;
    int ystep = (y1 < y2) ? 1 : -1;
    int y = y1;
    int maxX = x2;
    for(int x=x1; x<maxX; x++)
    {
        if(steep)
        {
            Console::gotoXY(y,x);
            cout << "*";
        }
        else
        {
            Console::gotoXY(x,y);
        cout << "*";
        }
        error -= dy;
        if(error < 0)
        {
            y += ystep;
            error += dx;
        }
    }
}

double Shape::round(double x)
{
    if (ceil(x+0.5) == floor(x+0.5))
    {
        int a = (int) ceil(x);
        if (a%2 == 0)
            return ceil(x);
        else
            return floor(x);
    }
    else 
        return floor(x+0.5);
}
void Shape::outputStatistics()
{
}

// This is the shape.h file
#pragma once
#include "console.h"
#include "vertex.h"
#include <iostream>
#include <list>
#include <cstdlib>
#include <cmath>
using namespace std;
#define PI 3.14159265358979323846
class Shape
{
    list<Vertex>::iterator itr;
protected:
    list<Vertex> vertices;
    Vertex centroid;
    void drawLine(int x1, int y1, int x2, int y2);
    Shape(Vertex point);
    double round(double x);
public:
    void drawShape();
    virtual int area() = 0;
    virtual int perimeter() = 0;
    virtual void outputStatistics();
    void rotate(double degrees);
    void scale(double factor);
};