C++ Inheritance Help

Need help understanding what is going on when I comment out // ovals[i].draw(); and replace it with Shape *s = &ovals[i]; s -> draw(); in the display() function in the main.cpp. I see the ovals are gone when I run the program but why is it happening?

Shape.h

#pragma once

#include

using std::string;

class Shape

{

protected:

string name;

int x, y, width, height;

public:

Shape(string name, int x, int y, int width, int height);

Shape();

~Shape();

void draw();

string getName();

int getX();

int getY();

int getWidth();

int getHeight();

bool pointInShape(int pointX, int pointY);

};

Shape.cpp

#include "Shape.h"

#include "gl/glut.h"

#include "gl/gl.h"

#include "gl/glu.h"

Shape::Shape()

{

name = " ";

x = 0;

y = 0;

width = 10;

height = 10;

}

Shape::Shape(string name, int x, int y, int width, int height) :

name(name), x(x), y(y), width(width), height(height)

{

}

Shape::~Shape()

{

}

void Shape::draw()

{

glColor3f(1, 0, 0);

glBegin(GL_LINES);

glVertex2f(108, 135);

glVertex2f(140, 157);

glVertex2f(145, 135);

glVertex2f(100, 157);

glEnd();

}

string Shape::getName()

{

return name;

}

int Shape::getX()

{

return x;

}

int Shape::getY()

{

return y;

}

int Shape::getWidth()

{

return width;

}

int Shape::getHeight()

{

return height;

}

bool Shape::pointInShape(int pointX, int pointY)

{

if ((pointX >= x) && (pointX < x + width) && (pointY >= y) && (pointY <= y + height))

return true;

return false;

}

Rectangle.h

#pragma once

#include "Shape.h"

#include

using std::string;

class Rectangle: public Shape

{

public:

Rectangle(string name, int x, int y, int width, int height);

Rectangle();

~Rectangle();

void draw();

};

Rectangle.cpp

#include "Rectangle.h"

#include "gl/glut.h"

#include "gl/gl.h"

#include "gl/glu.h"

Rectangle::Rectangle() : Shape()

{

name = "Rectangle";

x = 0;

y = 0;

width = 10;

height = 10;

}

Rectangle::Rectangle(string name, int x, int y, int width, int height) : Shape(name, x, y, width, height)

{

}

Rectangle::~Rectangle()

{

}

void Rectangle::draw()

{

glColor3f(0, 0, 1);

glBegin(GL_QUADS);

glVertex2f(x, y);

glVertex2f(x + width, y);

glVertex2f(x + width, y + height);

glVertex2f(x, y + height);

glEnd();

}

Oval.h

#pragma once

#include "Shape.h"

#include

using std::string;

class Oval: public Shape

{

public:

Oval(string name, int x, int y, int width, int height);

Oval();

~Oval();

void draw();

};

Oval.cpp

#include "Oval.h"

#include "gl/glut.h"

#include "gl/gl.h"

#include "gl/glu.h"

Oval::Oval() : Shape()

{

name = "Oval";

x = 0;

y = 0;

width = 10;

height = 10;

}

Oval::Oval(string name, int x, int y, int width, int height) : Shape(name, x, y, width, height)

{

}

Oval::~Oval()

{

}

void Oval::draw()

{

int centerX, centerY;

centerX = x + width / 2;

centerY = y + height / 2;

glColor3f(1, 0, 0);

glBegin(GL_TRIANGLE_FAN);

glVertex2f(centerX, centerY);

for (float angle = 0; angle < 360; angle += 1)

{

glVertex2f(centerX + sin(angle) * width / 2, centerY + cos(angle) * height / 2);

}

glEnd();

}

Main.cpp

#include "gl/glut.h"

#include "gl/gl.h"

#include "gl/glu.h"

#include

#include

#include

#include "Oval.h"

#include "Rectangle.h"

using std::string;

void init();

void display();

void handleButton(int button, int state, int x, int y);

void printText(int x, int y, string str);

void *font = GLUT_BITMAP_TIMES_ROMAN_24;//GLUT_STROKE_ROMAN;

const int WIDTH = 720;

const int HEIGHT = 480;

static int screenx = 0;

static int screeny = 0;

Oval ovals[3];

Rectangle rects[3];

int main(int argc, char** argv)

{

glutInit(&argc, argv);

glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_MULTISAMPLE | GLUT_DEPTH);

glutInitWindowSize(WIDTH, HEIGHT);

glutInitWindowPosition(0, 0);

glutCreateWindow("Just A Window");

init();

glutDisplayFunc(display);

glutMouseFunc(handleButton);

glutMainLoop();

return 0;

}

void init()

{

glClearColor(0.0, 0.0, 0.0, 0.0);

glColor3f(1.0, 1.0, 1.0);

glMatrixMode(GL_PROJECTION);

glLoadIdentity();

gluOrtho2D(screenx, screenx + WIDTH, screeny + HEIGHT, screeny);

ovals[0] = Oval("Oval 1", 10, 10, 100, 100);

ovals[1] = Oval("Oval 2", 200, 10, 150, 50);

ovals[2] = Oval("Oval 3", 10, 200, 200, 100);

rects[0] = Rectangle("Rect 1", 400, 50, 100, 75);

rects[1] = Rectangle("Rect 2", 200, 300, 75, 100);

rects[2] = Rectangle("Rect 3", 10, 320, 120, 40);

}

void display()

{

glClear(GL_COLOR_BUFFER_BIT);

for (int i = 0; i < 3; i++)

{

//ovals[i].draw();

Shape *s = &ovals[i];

s->draw();

rects[i].draw();

}

Shape s("Shape", 150, 150, 50, 50);

s.draw();

glutSwapBuffers();

glFlush();

return;

}

void handleButton(int button, int state, int x, int y)

{

static int index = -1;

if (button == GLUT_LEFT_BUTTON)

{

if (state == GLUT_DOWN)

{

for (int i = 0; i < 3; i++)

{

if (ovals[i].pointInShape(x, y))

{

glClear(GL_COLOR_BUFFER_BIT);

glColor3f(1, 1, 1);

printText(x + 30, y + 30, "You clicked " + ovals[i].getName());

glutSwapBuffers();

glFlush();

}

else if (rects[i].pointInShape(x, y))

{

glClear(GL_COLOR_BUFFER_BIT);

glColor3f(1, 1, 1);

printText(x + 30, y + 30, "You clicked " + rects[i].getName());

glutSwapBuffers();

glFlush();

}

}

}

if (state == GLUT_UP)

{

display();

}

}

}

void printText(int x, int y, string str)

{

int i, length;

glRasterPos2f(x, y);

length = str.length();

for (i = 0; i < length; i++)

{

glutBitmapCharacter(font, str[i]);

}

}