Please could you explain this code?

Please could you explain the following code in detail as i am so baffled and i do not know what this code exactly does. This is a game that basically draws multiple 3d objects i don't understand how and where the drawings were achieved so could you please explain thank you in advance

here is the code:

Code:

---


#ifndef _GAME_OBJECTS_H_
#define _GAME_OBJECTS_H_


class GameObjects
{
public:
        GameObjects();
        virtual void Update()=0; 
        virtual void Draw()=0;

        const float* GetPos();
        void SetPos(float x, float y, float z );

       
        bool m_deleteMe;
protected:
        float m_pos[3];
};

#endif

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This is a cpp file that i think it is also linked to the drawing of the 3d object

Code:

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GameObjects::GameObjects()
{
        m_deleteMe = false;
        m_pos[0] = m_pos[1] = m_pos[2] = 0.0f;
}

const float* GameObjects::GetPos(){
        return m_pos;
}

void GameObject::SetPos(float x, float y, float z ){
        m_pos[0] = x;
        m_pos[1] = y;
        m_pos[2] = z;
}

---

This is the 1st 3d object that I do not understand how it was drawn

Code:

---

#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include "glut.h"

#include "Object.h"


Object::Object()
{
        m_pos[2] = -2.8;
}
void Object::Update(){

}


void Object::Draw(){
       
        float color[] = {0.2,1.0,0.2,1.0};
        glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, color);

        glPushMatrix();
        glTranslatef(m_pos[0],m_pos[1],m_pos[2]);

        glPushMatrix();
        glutSolidCone(0.4,0.4f,12,12);
        glPopMatrix();

        for(int i=0; i<4; i++){
                glPushMatrix();
                glTranslatef(0,0,-0.15*(i+1));
                glutSolidCone(0.3f,0.4f,12,12);
                glPopMatrix();
        }
        glPushMatrix();
        glTranslatef(0,0,-0.15*5);
        glutSolidCone(0.5f,0.4f,12,12);
        glPopMatrix();

        glPopMatrix();

}

---

Please help guys

What does object.h file contains?

ssharish

Quote:

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Originally Posted by ssharish2005

What does object.h file contains?

ssharish

---

That's what it has

Code:

---

#ifndef _OBJECT_H_
#define _OBJECT_H_

#include "GameObjects.h"


class Object : public GameObjects
{
public:
        Object();
        void Update();
        void Draw();
};

#endif

---

Ok class object inherits from class GamesObject. That kind of makes sense now. So its quite diffcult to explain the whole code. I would appreciate if you point out which part of the code you dont understand. You will have to ask smart question rather than just asking anything.

It will take me ages to explain you that code. And i do not have that much time :)

ssharish

like ssharish2005 said, there are many things going on in there. The short version is that object:: Draw() is the one that tell openGL how to "plot" your 3D object-- in this case, it's a solid cone since you're calling glutSolidCone(). OpenGL uses stacks of matrices to manage your object and how you view the object. since matrices are stored in stack, you need to push and pop them.

Quote:

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Originally Posted by ssharish2005

Ok class object inherits from class GamesObject. That kind of makes sense now. So its quite diffcult to explain the whole code. I would appreciate if you point out which part of the code you dont understand. You will have to ask smart question rather than just asking anything.

It will take me ages to explain you that code. And i do not have that much time :)

ssharish

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Thank you for the response,

Could you please explain how the 3d object was drawn, and translated into positioned?

Quote:

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Originally Posted by Mehdi-110

Thank you for the response,

Could you please explain how the 3d object was drawn, and translated into positioned?

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for that particulate code check out: glutSolidCone
OpenGL can draw different object as well.

Quote:

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Originally Posted by nimitzhunter

for that particulate code check out: glutSolidCone
OpenGL can draw different object as well.

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Thank you for that,

but could you briefly explain how would one figure out the base , height , slices , stacks of glutSolidCone, would it be possible to initially draw it on a graph paper? or how would would initially figure it out before actually translating it into code? and could you also briefly explain how the colouring of that object was achieved, thank you so much for you help

You should start reading this book to understand the opengl uasage.
Chapter 1. Introduction to OpenGL

ssharish

Quote:

---

Originally Posted by ssharish2005

You should start reading this book to understand the opengl uasage.
Chapter 1. Introduction to OpenGL

ssharish

---

Thank you so much for your help,

could please explain the loop there, what does it do

Quote:

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Originally Posted by Mehdi-110

Thank you so much for your help,

could please explain the loop there, what does it do

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be honest here, is this a homework? ssharish gave you the link, go read it and play around.